Description:FIELD OF THE INVENTION
The present invention relates to industrially viable process for preparation of 7-dehydrocholesterol (7-DHC) from bisnoralcohol

BACKGROUND OF THE INVENTION
Cholest,5,7-diene-3-ß-ol, i.e. 7-dehydrocholesterol (7-DHC) of formula (I) is a zoosterol that functions in the serum as a cholesterol precursor and is an important precursor of vitamin D3 and its derivatives. 7-DHC is photochemically converted to vitamin D3 in the skin. 7-dehydrocholesterol has been synthesized in the prior art by various synthetic procedures. However, the procedures are lengthy and cumbersome which add to the cost of the process.

(I) (I)

With the objective to provide a cost effective process for synthesis of 7-DHC the present inventors envisaged the use of bisnoralcohol (BA) and surprisingly found a promising material for synthesis of 7-dehydrocholesterol in good yield and purity. This remains the objective of the invention.

SUMMARY OF THE INVENTION
In accordance with the above, the present invention provides an industrially viable process for synthesis of 7-dehydrocholesterol (7-DHC) from bisnoralcohol which comprises the steps of;
(i) Oxidizing bisnoralcohol (1) with p-chloranil in presence of solvent to (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene alcohol (2);

(ii) Protecting the 20-hydroxyl group of (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one (2) with tosylating or mesylating agent in presence of acid scavenger and solvent to obtain (20S)-20-tosyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene Tosylate (3) or (20S)-20-mesyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene mesylate (3’)

(iii) Protecting the ketonic group of compound (3) or (3’) with a protecting agent in presence of alkyl ester of orthoformic acid and weak acid to obtain (2S)-2-(9a,11a-dimethyl-1,2,3,3a,3b,8,9,9a,9b,10,11,11a-dodecahydrospiro[cyclo penta [a] phenan threne-7,2'-[1,3]dioxolan]-1-yl)propyl 4-methylbenzene-1-sulfonate i.e.3-Ketal bisnordiene tosylate (4) or 3-Ketal bisnordiene mesylate (4’);

(iv) Coupling 3-Ketal Bisnoralcohol Tosylate(4) or 3-Ketal Bisnoralcohol mesylate (4’) with Grignard reagent in presence of Copper (I) catalyst and the solvent to yield 3-Ketal 4,6- Cholestadiene (5);

(v) Deprotecting 3-Ketal 4,6- Cholestadiene (5) in presence of acid and water to obtain Cholest-4,6-diene-3-one (6);

(vi) Acylating Cholest-4,6-diene-3-one (6) with acylating agent in presence of acid catalyst to obtain 3-Acetoxy- 3,5,7 Cholesta-triene (7);

(vii) Reducing 3-Acetoxy- 3,5,7 Cholesta-triene (7) with reducing agent and the solvent to obtain 7-dehydrocholesterol as major and Epi -7 -Dehydrocholesterol as side product.

DESCRIPTION OF FIGURES:
Figs 1(a) and 1(b): Mass Spectra of the compound (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene alcohol (2).
Figs 2(a) to 2(d): 13CNMR of the compound (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene alcohol (2).
Figs 3(a) and 3(b): 1HNMR of the compound (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene alcohol (2).
Figs 4(a) and 4(b): Mass Spectra of the compound Bisnordiene Tosylate (3).
Figs 5(a) to 5(c): 13CNMR of the compound Bisnordiene Tosylate (3).
Figs 6(a) to 6(c): 1HNMR of the compound Bisnordiene Tosylate (3).
Figs 7(a) and 7(b): Mass Spectra of the compound (2S)-2-(9a,11a-dimethyl-1,2,3,3a,3b,8,9,9a,9b,10,11,11a-dodecahydrospiro[cyclopenta[a]phenanthrene-7,2'-[1,3]dioxo lan]-1-yl)propyl 4-methyl benzene-1-sulfonate i.e. 3-Ketal Bisnordiene Tosylate (4).
Figs 8(a) to 8(c): 13CNMR of the compound (2S)-2-(9a,11a-dimethyl-1,2,3,3a,3b,8,9,9a,9b,10,11,11a-dodecahydrospiro[cyclopenta[a]phenanthrene-7,2'-[1,3]dioxo lan]-1-yl)propyl 4-methyl benzene-1-sulfonate i.e. 3-Ketal Bisnordiene Tosylate (4).
Fig 9(a) to 9(d): 1HNMR of the compound (2S)-2-(9a,11a-dimethyl-1,2,3,3a,3b,8,9,9a,9b,10,11,11a-dodecahydrospiro[cyclopenta[a]phenanthrene-7,2'-[1,3]dioxo lan]-1-yl)propyl 4-methyl benzene-1-sulfonate i.e. 3-Ketal Bisnordiene Tosylate (4).

Figs 10(a) and 10(b): Mass spectra of the compound Cholest-4,6-diene-3-one (6).
Figs 11(a) to 11(c) : 13CNMR of the compound Cholest-4,6-diene-3-one (6).
Figs 12(a) to 12(c):1HNMR of the compound Cholest-4,6-diene-3-one (6).
Figs 13(a) and 13(b): Mass spectra of the compound 3-Acetoxy- Cholest-3,5-diene(7).
Figs 14(a) to 14(c):13CNMR of the compound 3-Acetoxy- Cholest-3,5-diene(7).
Figs 15(a) to 15(c): 1HNMR of the compound3-Acetoxy- Cholest-3,5-diene(7).
Figs 16(a) and 16 (b): Mass spectra of the compound 7-dehydrocholesterol
Figs 17(a) to 17(c):13CNMR of the compound7-dehydrocholesterol
Figs 18(a) to 18(d): 1HNMR of the compound 7-dehydrocholesterol

DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be explained in detail with reference to its various preferred as well as optional embodiment, which, however should not be construed to limit the scope of the invention.

The present process offers economical and efficient process for synthesis of 7-DHC from bisnoralcohol that can be scaled to industrial level.

The present process steps will now be described in detail as follows:
Step 1: Conversion of Bisnoralcohol (1) to (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene alcohol (2).
To the bisnoralcohol (1) suspended in the solvent was added the mild oxidizing agent p-chloranil at a temperature of 25oC to 35oC. The mixture was heated to a temperature of 40oC to 70oC till TLC indicated absence of the starting material. The solvent was distilled out and to the residue was added suitable solvent, washed with a basic solution and water, evaporated and dried to yield (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene alcohol (2).
The solvent was selected from C1-C6 straight or branched alcohol, aromatic hydrocarbon such as toluene, halogenated hydrocarbons alone or mixtures thereof. The basic solution is preferably 5% alkali hydroxide solution.

Step 2: (i) Conversion of (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one (2) to obtain (20S)-20-tosyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene Tosylate (3).
To the Bisnordiene alcohol (2) obtained in step 1 was added the base, solvent and the tosylating the agent selected from para toluene sulphonyl chloride at ambient temperature of 25oC to 35oC. The reaction mixture was stirred for 12-18 hours till TLC analysis indicated absence of the starting material. The mixture was then washed with 1:1 HCl solution followed by washing with water and finally with 8% sodium bicarbonate solution. The solvent layer was evaporated and the residue dried to obtain (20S)-20-tosyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene Tosylate (3).

The base as the acid scavenger in the process step is selected from aliphatic or aromatic base which include but is not limited to triethylamine, Di isopropyl ethyl amine, pyridine, imidazole and the like alone or mixtures thereof. The solvent is selected from halogenated hydrocarbons, aromatic or aliphatic hydrocarbons, esters, amines and the like alone or mixtures thereof.

Step 2(ii): Conversion of (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one (2) to obtain (20S)-20-mesyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene Tosylate (3’).
The procedure followed is same as that described in step 2(i) except for the use of methane sulphonyl chloride as the mesylating agent.

Step 3: (i) Conversion of (20S)-20-tosyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene Tosylate (3) to (2S)-2-(9a,11a-dimethyl-1,2,3,3a,3b,8,9,9a,9b,10,11,11a-dodeca hydro spiro [cyclopenta[a]phenanthrene-7,2'-[1,3]dioxolan]-1-yl)propyl4-methyl benzene-1-sulfonate i.e. 3-Ketal Bisnordiene Tosylate (4) .
To the solution of Bisnordiene Tosylate (3) obtained in step 2 was added ethylene glycol or Propane1,3 diol and alkyl ester of orthoformic acid at ambient temperature of 25oC to 35oC. This was followed by addition of weak acid and the reaction mixture was stirred for 12-18 hours till the TLC analysis indicated absence of the starting material. Added base to the reaction mass to adjust the pH 8-9 followed by addition of water and 10% sodium chloride solution. The solvent layer was evaporated, purified to obtain 2S)-2-(9a,11a-dimethyl-1,2,3,3a,3b,8,9,9a,9b,10,11,11a-dodecahydrospiro[cyclopenta[a]phenanthrene-7,2'-[1,3]dioxolan]-1-yl)propyl 4-methylbenzene-1-sulfonate i.e. 3-Ketal Bisnordiene Tosylate (4).
The solvent for the process step is selected from aliphatic or aromatic hydrocarbons which include but is not limited to n-hexane, n-heptane, toluene; halogenated hydrocarbons, ethers alone or mixtures thereof. The alkyl ester of orthoformic acid as water quenching agent is selected from trimethyl orthoformate or triethyl orthoformate. The acid to carry the reaction in forward direction is selected from Para toluene sulphonic acid monohydrate. The base to adjust the pH is selected from organic or inorganic base such as trietheylamine, NaOH, KOH and the like.

Step 3(ii): Conversion of (20S)-20-mesyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene mesylate (3’) to 3-Ketal Bisnordiene mesylate (4’).
The procedure is same as that disclosed in step 3(i) except the starting material is (20S)-20-mesyloxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene mesylate (3’).

Step 4: (i) Conversion of 3-Ketal Bisnordiene Tosylate (4) to 3-Ketal 4,6- Cholestadiene (5).
To the magnesium turnings suspended in the solvent at 40oC-50oC under nitrogen atmosphere was added drop wise 1st lot of alkyl halide at the same temperature followed by addition of 1,2 dibromoethane to initiate the reaction. On effervescence was slowly added another lot of alkyl halide and the reaction mixture was stirred for about 60 minutes. The reaction mass was cooled to 0-10oC. The catalyst and the solution of the compound 3-Ketal Bisnordiene Tosylate (4) obtained in step 3 were added simultaneously to the cooled reaction mass and the mixture was stirred till TLC indicated completion of reaction. The reaction mass was cooled to 10°C, quenched reaction mass with ammonium chloride solution and then extracted in the suitable solvent. The entire organic layer was then evaporated under vacuum and the residue was crystalized using alcohol to yield 3-Ketal 4,6- Cholestadiene (5).
The solvent for the process is selected from THF, 2- Methyl tetra hydro furan, methyl-tert butyl ether; diethyl ether, isopropylether and the like. The coupling reaction with the Grignard reagent is carried out in presence of catalyst selected from Cu(1) iodide, Cu(1) bromide or Cu(1) chloride or Cu(I) bromide dimethyl sulphide complex.

Step 4 (ii): Conversion of 3-Ketal Bisnordiene Mesylate (4’) to 3-Ketal 4,6- Cholestadiene (5).
The procedure is same as that described in step 4(i).

Step 5: Conversion of 3-Ketal 4,6- Cholestadiene (5) to Cholest-4,6-diene-3-one (6)
To 3-Ketal 4,6- Cholestadiene (5) obtained in step 4 was added the solvent, acid and the mixture was stirred till TLC indicated completion of the reaction. The mixture was then washed with water and the solvent layer was evaporated under vacuum to obtain the residue Cholest-4,6-diene-3-one (6) and crystallized.
The solvent is selected from lower alcohols, esters such as ethyl acetate, ketone such as acetone, aromatic hydrocarbon such as toluene and the like alone or mixtures thereof. The acid is selected from organic or inorganic acids such as para toluene sulphonic acid, HCl and the like.

Step 6: Conversion of Cholest-4,6-diene-3-one (6) to 3-Acetoxy- 3,5,7 Cholesta-triene (7).
To Cholest-4,6-diene-3-one (6) obtained in step 5 was added suitable acylating agent at 25-35oC and the mixture was stirred for 6-8 hours at 105-110 °C till the TLC analysis indicated the absence of starting material. Cooled the reaction mass to ambient temperature. Quenched the reaction mass in ice cold water solution followed by quenching in water and finally extracted in suitable solvent. Washed the organic layer with 8% sodium icarbonate solution and the organic layer was evaporated to get the residue 3-Acetoxy- Cholest-3,5-diene (7) and further purified.

The acylating agent is selected from the mixture of acetic anhydride and acetyl chloride, isopropenyl acetate and sulphuric acid, benzoic anhydride and benzoyl chloride, propionic anhydride and propionyl chloride, isobutyric anhydride and isobutyl chloride, trifluroacetic anhydride and trifluroacetyl chloride. The solvent is selected from halogenated hydrocarbons, esters, ketones and the like alone or mixtures thereof.

Step 7: Conversion of 3-Acetoxy- 3,5, 7-Cholesta-triene (7) to 7-dehydrocholesterol
To calcium chloride was charged alcohol and the solution was cooled to 5-10oC. This was followed by slow addition of alkali metal borohydride or its derivative and the mixture was stirred for about 30 minutes at 40-50oC. The solution of the compound 3-Acetoxy- 3,5,7-Cholesta-triene (7) obtained in step 6 was slowly added at the temperature and stirred till TLC indicated completion of the reaction. Quenched the reaction mass in ice cold water and extracted in suitable solvent. Washed with acid to yield crude product 7-DHC with HPLC purity 60%-70% and epi-7Dehydrocholetserol in the range of 10% -30%.

Purification:
The crude 7-DHC was dissolved in the suitable solvent and heated to about 65oC, maintained at same temperature for about 30 minutes, allowed to cool to 25-30oC, chilled to 10-15oC, filtered washed and dried under vacuum at about 50oC to obtain 7-DHC with HPLC purity of about 97%.

Alternately, the crude 7-DHC was purified using column chromatography using silica column with 5% Acetone in Toluene as the elute.

The solvent is selected from lower alcohol such as ethanol, methanol, IPA, t-butanol; aliphatic or aromatic hydrocarbons; esters; ethers; ketones; halogenated hydrocarbons alone or mixtures thereof. The acid is selected from organic or inorganic acid such as 50% acetic acid or 2N HCl.

Other features and embodiments of the invention will become apparent by the following examples which are given for illustration of the invention rather than limiting its intended scope. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art.

Examples:
Example 1: Preparation of (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one i.e. Bisnordiene alcohol (2) from Bisnoralcohol.
General Procedure:
Bisnoralcohol (303 millimole) charged in methanol was reacted with p-chloranil (1.1-1.59 mole equivalent) preferably 1.27 mole equivalent at 40-65oC, preferably at 60-65oC for 4-18 hours preferably 4 hrs to synthesise Bisnordiene alcohol (2).

Example 1(a): 100gms (303 millimole) of Bisnoralcohol was suspended in 300 ml of methanol along with 95gms (386 millimole) of para- chloranil at 25-35°C. The reaction mass was heated to 60-65°C for 4 hours till the TLC analysis indicated absence of starting material, Distilled out methanol, charged Dichloromethane (1000 ml) and washed with 1000 ml 5% KOH solution followed by washing with 500ml water and Dichloromethane layer was evaporated to obtain the residue Bisnordiene alcohol (2).
Yield: 90gm; Percentage Yield: 90%
HPLC purity: 85%.

Example 1(b): 100 gms (303 millimole) of Bisnoralcohol was suspended in 300 ml toluene along with 100 gms(406 millimole) of para- chloranil at 25-35°C. The reaction mass was heated to 60-65°C for 4 hours till the TLC analysis indicated absence of starting material. Distilled out toluene, charged Dichloromethane (1000 ml), washed with 1000 ml 5% KOH solution followed by washing with 500 ml water and Dichloromethane layer evaporated to obtain the residue Bisnordiene alcohol (2).
Yield: 92gm; Percentage Yield: 92.9%
HPLC purity: 84%

Example 1(c): 100 gms (303 millimole) of Bisnoralcohol was suspended in 300 ml of Isopropyl alcohol along with 100 gms(406 millimole) of para- chloranil at 25-35°C. The reaction mass was heated to 40-45°C for 12hours till the TLC analysis indicated absence of starting material. Distilled out methanol, charged dichloromethane (1000 ml). Washed with 1000 ml 5% NaOH solution followed by washing with 500ml water and Dichloromethane layer was evaporated to obtain the residue Bisnordiene alcohol (2).
Yield: 95gm; Percentage Yield: 95%
HPLC purity: 84%

Example 1(d): 100 gms (303 millimole) of Bisnoralcohol was suspended in 300 ml of tertiary butanol along with 100 gms(406 millimole) of para- chloranil at 25-35°C. The reaction mass was heated to 60-65°C for 4 hours till the TLC analysis indicated absence of starting material. Distilled out methanol, charged methylene dichloride (1000 ml). Washed with 1000 ml 5% KOH solution followed by washing with 500ml water and Dichloromethane layer was evaporated to obtain the residue Bisnordiene alcohol (2) (90gm).
Yield: 90gm; Percentage Yield: 90%
HPLC purity: 85%

The residue was further crystallized in methanol 100 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 25 ml, dry the filtered product to obtain the solid Bisnordiene alcohol (2).
Yield: 50gm; Percentage Yield 50%
HPLC purity: 96%

Example 2: Preparation of Bisnordiene Tosylate (3).

General Procedure:
Bisnordienealcohol (2) dissolved in Dichloromethane was treated with p-toluene sulphonyl chloride (1.7-2.0 mole equivalent) preferably 1.7 mole equivalent in presence of pyridine(4-20 mole equivalent) preferably 4.1 mole equivalent at 10-40oC, preferably at 30-40oC for 8-16 hrs preferably 12 hrs to synthesise Bisnordiene Tosylate (3).

Example 2(a): 100 gms (304.8 millimole) of Bisnordiene alcohol (2) was suspended in 500 gm (6944 millimole) of pyridine and 500 ml Dichloromethane along with 120 gms (630 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass was stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed the residue with 500ml 1:1 HCl solution followed by 500ml water and finally with 500 ml of 8% sodium bicarbonate solution. The dichloromethane layer was evaporated to get the residue Bisnordiene Tosylate (3).
Yield: 134gm; Percentage Yield: 93%
HPLC purity: 92%

Example 2(b): 100gms (304.8milimole) of Bisnordienealcohol (2) was suspended in 100gm (1388 millimole) of pyridine and 500 ml Dichloromethane along with 120gms (630 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed the mixture with 500ml 1:1 HCl solution followed by 500ml water and finally with 500 ml of 8% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue Bisnordiene Tosylate (3).
Yield: 138gm; Percentage Yield: 94.5 %
HPLC purity: 91%

Example 2(c): 1gm(3.04milimole) of Bisnordienealcohol (2) was suspended in 5gm (69.44 millimole) of pyridine and 50ml chloroform along with 1.8gm (9.46 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass was stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed the mixture with 50ml 1:1 HCl solution followed by 50ml water and finally with 50 ml of 8% sodium bicarbonate solution. The dichloromethane layer was evaporated to get residue Bisnordiene Tosylate (3).
Yield: 1.4gm; Percentage Yield 97%.
HPLC purity: 86%
The residue was then crystalized from methanol.
The residue was further crystallized in methanol 5 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 2 ml, dry the filtered product
Yield: 1.0gm; Percentage Yield: 69%
HPLC purity: 96%

Example 2(d): 1gm (3.04milimole) of Bisnordienealcohol (2) was suspended in 5gm (69.44 millimole) of pyridine along with 1.5 gms (7.88 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed the mixture with 50ml 1:1 HCl solution followed by 50ml water and finally with 50 ml of 8% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue Bisnordiene Tosylate (3).
Yield: 1.4gm; Percentage Yield: 97%.
HPLC purity: 85%
The residue was crystallized from methanol.
The residue was further crystallized in methanol 5 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 2 ml, dry the filtered product
Yield: 1.1 gm; Percentage Yield: 76%
HPLC purity: 92%

Example 2 (e): 1gm (3.04milimole) of Bisnordienealcohol (2) was suspended in 5gm (49.41 millimole) of Triethyl amine and 50ml Dichloromethane along with 1.1 gm (5.77 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed the mixture with 50ml 1:1 HCl solution followed by 50 ml water and finally with 50ml of 8% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue Bisnordiene Tosylate (3).
Yield: 1.4gm; Percentage Yield 97%
HPLC purity: 85%
The residue was crystallized from acetone
The residue was further crystallized in acetone 5 ml stir at 25-30°C chill to 5-10°C filter it wash by chill acetone 2 ml, dry the filtered product
Yield: 1.0 gm; Percentage Yield 69%
HPLC purity: 93%

Example 2(f): 1gm (3.04milimole) of Bisnordienealcohol (2) was suspended in 5gm (73.44 millimole) of Imidazole and 50ml Ethyl Acetate along with 1.1 gms(5.77 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material wash with 50ml 1:1 HCl solution followed by 50 ml water and finally with 50 ml of 8% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue Bisnordiene Tosylate (3).
Yield: 1.4gm; Percentage Yield 97%
HPLC purity: 83%
The residue was crystallized from methanol.
The residue was further crystallized in methanol 5 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 2 ml, dry the filtered product
Yield: 0.8 gm; Percentage Yield 55%
HPLC purity: 91%

Example 2(g): 1gm (3.04milimole) of Bisnordienealcohol (2) was suspended in 5gm (38.68 millimole) of Diisopropylethylamine and 50 ml Ethyl Acetate along with 1.1 gms(5.77 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed the mixture with 50ml 1:1 HCL solution followed by 50ml water and finally with 50ml of 8% sodium bicarbonate solution. The dichloromethane layer was evaporated to get residue Bisnordiene Tosylate (3).
Yield: 1.2 gm; Percentage Yield: 83%
HPLC purity: 84%

Example 2(h): 1gm (3.04milimole) of Bisnordienealcohol (2) was suspended in 5gm (69.44 millimole) of pyridine along with 1.5 gms(7.88 millimole) of para toluene sulphonyl chloride at 25-35°C. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed with 50ml 1:1 HCl solution followed by 50 ml water and finally with. 50 ml of 8% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue Bisnordiene Tosylate (3).
Yield: 1.4gm; Percentage Yield: 97%
HPLC purity: 85%

Example 2(i): 1gm (3.04milimole) of Bisnordienealcohol (2) was suspended in 5gm (69.44 millimole) of pyridine along with 1.5 gms(13.09 millimole) of Methane sulphonyl chloride at 25-35°C. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Washed the mixture with 50ml 1:1 HCl solution followed by 50 ml water and finally with 50 ml of 8% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue Bisnordiene mesylate (3’).
Yield: 1gm; Percentage Yield: 69 %
HPLC purity: 83%

Example 3: Preparation of (2S)-2-(9a,11a-dimethyl-1,2,3,3a,3b,8,9,9a,9b,10,11,11a-dodecahydrospiro[cyclopenta[a]phenanthrene-7,2'-[1,3]dioxolan]-1-yl)propyl 4-methyl benzene-1-sulfonate i.e. 3-Ketal Bisnordiene Tosylate (4)
General Procedure:
Bisnordiene Tosylate (3) of example 2 in MDC was treated with ethylene glycol (7.82 to 15.63 mole equivalence), preferably 15.53 mole equivalence in presence of trimethyl orthoformate (2.28 to 9.14 mole equivalence) preferably 6.88 mole equivalence, in presence of p- toluene sulphonic acid(0.05 to 0.1 mole equivalence) preferably 0.05 mole equivalence at 25 to 120oC preferably at 25-32oC to synthesise 3-Ketal Bisnordiene Tosylate (4).

Example 3(a):100 gms (273.85 millimole) of Bisnordiene Tosylate (3) was suspended in 500 ml dichloromethane along with 200gm (3222 millimole) of ethylene glycol 25-35°C and charged 200 gm (1884 millimole) of trimethyl orthoformate. Added 2.0gm (10.5 millimole) p- toluene sulphonic acid. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Added Triethylamine to adjust pH 8-9 followed by addition of 100 ml water and finally 100 ml of 10% sodium chloride solution. The dichloromethane layer evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 106gm; Percentage Yield: 97%
HPLC purity: 87%

Example 3(b): 100 gms (273.85millimole) of Bisnordiene Tosylate (3) was suspended 500 ml toluene along with 200gm (3222 millimole) of ethylene glycol at 25-35°C. Then charged 2.0 gm of para toluene sulphonic acid (10.5millimole). The reaction mass stirred for 18-24 hours at reflux with Dean stark apparatus till the TLC analysis indicated the absence of starting material. Added triethylamine to adjust pH to 8-9 followed by addition of 10 ml water and finally 100 ml of 10% sodium chloride solution. The dichloromethane layer evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 95gm; Percentage Yield: 87%
HPLC purity: 85%
Example 3(c): 1gm (2.73 millimole) of Bisnordiene Tosylate (3) was suspended in 20ml Dichloromethane along with 2gm(32.22 millimole) of Ethylene Glycol at reflux temperature. Charged 2 gm(18.84 millimole) of trimethyl orthoformate. Added 0.02gm of para toluene sulphonic acid the reaction mass stirred for 6-12 hours till the TLC analysis indicated the absence of starting material. Added triethylamine to adjust pH to 8-9 followed by addition of 10 ml water and finally with 10 ml of 10% sodium chloride solution. The dichloromethane layer evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 1.0gm; Percentage Yield: 91%
HPLC purity: 90%

Example 3(d): 1 gm (2.73 millimole) of Bisnordiene Tosylate (3) was suspended in 20 ml Dichloromethane along with 2gm (26.28 millimole) of Propane1,3 diol 25-35°C. Charged 2 gm (18.84 millimole) of trimethyl orthoformate. The reaction mass stirred for 12-18 hours till the TLC analysis indicated the absence of starting material. Added triethylamine to adjust pH to alkaline followed by 10 ml water and finally with 10 ml of 10% sodium chloride solution. The dichloromethane layer evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 0.9 gm; Percentage Yield: 82%
HPLC purity: 92%

Example 3(f): 1 gm (2.07 millimole) of Bisnordiene Tosylate (3) was suspended in 20 ml Toluene along with 1gm (16.1 millimole) of Ethylene Glycol at 25-35°C. Charged 0.5 gm(4.71 millimole) of trimethyl orthoformate. The reaction mass stirred for 6-18 hours till the TLC analysis indicated the absence of starting material. Added triethylamine to adjust pH 8-9 followed by addition of 10 ml water and finally 10 ml of 10% sodium chloride solution. The dichloromethane layer evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 1.03gm; Percentage Yield: 94%.
HPLC purity:.80%
The residue was purified from toluene.
The residue was further crystallized in toluene 5 ml stir at 25-30°C chill to 5-10°C filter it wash by chill toluene 2 ml, dry the filtered product
Yield: 0.8gm; Percentage Yield 73%
HPLC purity: 95%

Example 3(g): 1 gm (2.73 millimole) of Bisnordiene Tosylate (3) was suspended in 20 ml Toluene along with 2 gm(32.22 millimole) of Ethylene Glycol at reflux temperature. Charged 2 gm (18.84 millimole) of trimethyl orthoformate. Added 0.02 gm of sulphuric acid. The reaction mass was stirred for 6-12 hours till the TLC analysis indicated the absence of starting material. Added triethylamine to adjust pH 8-9 followed by 10 ml water and finally 10 ml of 10% sodium chloride solution. The dichloromethane layer was evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 1.0gm; Percentage Yield: 91 %
HPLC purity: 90%

Example 3(h): 1 gm (2.73 millimole) of Bisnordiene Tosylate (3) was suspended in 20 ml heptane along with 2 gm(32.22 millimole) of Ethylene Glycol at reflux temperature. Charged 2 gm(13.49 millimole) of Triethyl ortho formate. Added 0.02 gm of sulphuric acid the reaction mass stirred for 6-12 hours till the TLC analysis indicated the absence of starting material. Added pyridine to adjust pH 8-9 followed by addition of 10ml water and finally with 10 ml of 10% sodium chloride solution. The dichloromethane layer evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 0.8gm; Percentage Yield: 73%
HPLC purity: 92%

Example 3(i): 1 gm (2.07 millimole) of Bisnordiene Tosylate (3) was suspended 20 ml Toluene along with 1 gm (16.1 millimole) of Ethylene Glycol 25-35°C. Charged 0.5 gm(4.71 millimole) of trimethyl orthoformate. The reaction mass stirred for 6-18 hours till the TLC analysis indicated the absence of starting material. Added triethylamine to adjust pH to alkaline followed by addition of 10 ml water and finally with 10 ml of 10% sodium chloride solution. The dichloromethane layer evaporated to get residue 3-Ketal Bisnordiene Tosylate (4).
Yield: 1.06gm; Percentage Yield: 95%
HPLC purity: 84%
The residue was further purified using methanol
The residue was further crystallized in methanol 5 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 2 ml, dry the filtered product
Yield: 1gm; Percentage Yield: 91 %
HPLC purity: 93%
The compound Bisnordiene Tosylate (3’) can be converted to 3-Ketal Bisnordiene mesylate (4’) by the process illustrated above.

Example 4: Preparation of 3-Ketal 4,6- Cholestadiene (5)
General procedure:
3-Ketal Bisnoralcohol Tosylate (4) was treated with Isopentyl Magnesium Bromide (2 to 8 mole equivalence) preferably in 4 mole equivalence in THF at 0-25oC preferably at 15oC with cuprous (1) catalyst about 0.0097 mole equivalence to yield 3-Ketal 4,6- Cholestadiene (5).

Example 4(a): 100gms (4166 millimole) of Magnesium turnings was suspended in 500ml of Dry Tetrahydrofuran at 40-50°Cunder nitrogen atmosphere. 1.0gm (6.62 millimole) of isopentyl bromide was added at 40-50°C drop wise to initiate the reaction with help of 1,2 dibromoethane. Once the vigorous effervescence started was added slowly 200 gm(1324 millimole) of Isopentyl bromide and reaction mass was stirred for 60 minutes. The reaction mass was cooled to 0-10°C. Catalyst cuprous iodide 5.0 gm(26.25 millimole) and 100 gm(190.11 millimole) of the compound 3-Ketal Bisnordiene Tosylate (4) obtained in example 3 dissolved in 300 ml tetrahydrofuran were added simultaneously and stirred till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C, quenched the reaction mass with 500ml of 10% ammonium chloride solution and then extracted in 500 ml ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 65.0gm; Percentage Yield: 81%
HPLC purity: 85%

Example 4(b): 50 gms (2083 millimole) of magnesium turnings was suspended in 500ml of dry tetrahydrofuran at 50-60°C under nitrogen atmosphere. 1gm ( 6.62 millimole) of isopentyl bromide was added at 40-50°C drop wise to initiate the reaction. Once the vigorous effervescence started slowly added 100 gm(662 millimole) of Isopentyl bromide and reaction mass was stirred for 60 minutes. The reaction mass was then cooled to 0-10°C. Catalyst cuprous bromide 1.0 gm(34.85milimole) and 100 gm(190.11 millimole) of the compound 3-Ketal Bisnordiene Tosylate (4) dissolved in 150ml Tetrahydrofuran were added simultaneously and the mixture was stirred till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C, quenched the reaction mass with 500 ml of 10%ammonium chloride solution and then extracted in 500ml ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 75 gm; Percentage Yield: 93%
HPLC purity: 80%
The residue was further yield purified in acetone.
The residue was further crystallized in methanol 100 ml stir at 25-30°C chill to 5-10°C filter it wash by chill Acetone 25 ml, dry the filtered product
Yield: 25gm; Percentage Yield: 31%
HPLC purity: 92%

Example 4(c): 5.0 gms (208.4 millimole) of magnesium turnings was suspended in 50ml of methyl-tert butyl ether at 40-50°Cunder nitrogen atmosphere. 1 gm(6.62 millimole) of isopentyl bromide was added at 40-50°C drop wise to initiate the reaction with help of 1,2 dibromoethane. Once the vigorous effervescence started slowly added 15gm(97.37 millimole) of Isopentyl bromide and reaction mass was stirred for 60 minutes. The reaction mass was cooled to 0-10°C. The catalyst cuprous bromide dimethyl sulfide 0.1 gm(0.486milimole) and 10 gm(19.0milimole) of the compound 3-Ketal Bisnordiene Tosylate (4) dissolved in 50 ml methyl-tert Butyl ether were added simultaneously and the mixture was stirred till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C. Quenched the reaction mass with 10% ammonium chloride solution in 50 ml water and then extracted in Methyl-tert butyl Ether 50 ml. The entire organic layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 3.2gm; Percentage Yield: 80%
HPLC purity: 85%
The residue was crystalized using Isopropyl alcohol.
The residue was further crystallized in isopropyl alcohol 10 ml stir at 25-30°C chill to 5-10°C filter it wash by chill Isopropyl alcohol 5 ml, dry the filtered product
Yield: 1.5 gm ; Percentage Yield: 37 %
HPLC purity: 91%

Example 4(d): 5.0 gms (208.4 millimole) of magnesium turnings was suspended in 50ml of dry Diethyl Ether at 40-50°Cunder nitrogen atmosphere. 1 gm(6.62 millimole) of isopentyl bromide was added at 28-32°C drop wise to initiate the reaction with help of 1,2 dibromoethane. Once the vigorous effervescence started slowly added 15 gm(97.37 millimole) of Isopentyl bromide and reaction mass was stirred for 60 minutes. The reaction mass was then cooled to 0-10°C. The catalyst cuprous bromide dimethyl sulfide.1 gm(0.486milimole) and10 gm(190 millimole) of the compound 3-Ketal Bisnordiene Tosylate (4) dissolved in 50ml diethyl ether were added simultaneously and stirred till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C. Quenched the reaction mass with with 10% ammonium chloride solution in 50 ml water and then extracted in Diethyl Ether 50 ml, The organic layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 3.0 gm; Percentage Yield: 75%
HPLC purity: 87%
The residue was crystalized ethyl alcohol.
The residue was further crystallized in ethanol 15 ml stir at 25-30°C chill to 5-10°C filter it wash by chill ethanol 5 ml, dry the filtered product
Yield: 2.0 gm; Percentage Yield: 50%
HPLC purity: 92%

Example 4(e): 5.0 gms (208 millimole) of magnesium turnings was suspended in 50ml of 2- Methyl Tetra hydrofuran at 55-60°Cunder nitrogen atmosphere. 1 gm(6.62 millimole) of isopentyl bromide was added at 55-60°C drop wise to initiate the reaction with help of 1,2 dibromoethane. Once the vigorous effervescence started slowly added 15gm(97.37 millimole) of Isopentyl bromide and reaction mass was stirred for 60 minute. The reaction mass was cooled to 0-10°C. The catalyst cuprous bromide dimethyl sulfide 0.1 gm(0.486milimole) and 10 gm(190 millimole) of the compound 3-Ketal Bisnordiene Tosylate (4) was dissolved in 50 ml diethyl ether were added simultaneously and stirred till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C. Quenched the reaction mass with 10% ammonium chloride solution in 50 ml water and then extracted in Diethyl Ether 50 ml, The organic layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 3.0 gm; Percentage Yield 75%
The residue was crystalized using acetone
The residue was further crystallized in acetone 10 ml stir at 25-30°C chill to 5-10°C filter it wash by chill acetone 5 ml, dry the filtered product.
Yield: 1.0 gm; Percentage Yield: 25%
HPLC purity: 87%

Example 4(f): 5.0 gms (208.4 millimole) of magnesium turnings was suspended in 50ml of Tetrahydrofuran at 40-50°Cunder nitrogen atmosphere. 1 gm(6.62 millimole) of isopentyl bromide was added at 40-50°C drop wise to initiate the reaction with help of 1,2 dibromoethane. Once the vigorous effervescence started slowly added 15gm(97.37 millimole) of Isopentyl bromide and reaction mass was stirred for 60 minutes. The reaction mass was cooled to 0-10°C. The catalyst cuprous chloride 0.1 gm(1.01milimole) and 10 gm (19 milimole) of the compound-Ketal Bisnordiene Tosylate (4) dissolved in 50 ml tetrahydrofuran were added simultaneously and stirred the mixture till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C. Quenched the reaction mass with 10% ammonium chloride solution in 50 ml water and then extracted in Methyl-tert butyl Ether.50 ml. The entire organic layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 3.0gm; Percentage Yield: 75%
HPLC purity: 85%
The residue was crystalized using methanol
The residue was further crystallized in methanol 10 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 5 ml, dry the filtered product
Yield: 1.3gm; Percentage Yield: 32%
HPLC purity: 91%

Example 4(g): 5.0 gms (208.4 millimole) of magnesium turnings was suspended in 50ml of Tetrahydrofuran at 40-50°Cunder nitrogen atmosphere. 1 gm(6.62 millimole) of isopentyl bromide was added at 40-50°C drop wise to initiate the reaction with help of 1,2 dibromoethane. Once the vigorous effervescence started slowly added 15gm(97.37 millimole) of Isopentyl bromide and reaction mass was stirred for 60 minutes. The reaction mass was cooled to 0-10°C. The catalyst cuprous iodide 0.1gm and 10 gm(19 milimole) of the compound 3-Ketal Bisnordiene Tosylate (4) dissolved in 50 ml tetrahydrofuran was added simultaneously and the mixture was stirred till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C. Quenched the reaction mass with 10% ammonium chloride solution in 50 ml water and then extracted in Toluene 50 ml . The entire organic layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 3.0gm; Percentage Yield: 83%
HPLC purity: 86%
The residue was crystalized using alcohol.
Yield 1.1 gm; Percentage Yield: 30%
HPLC purity: 90%

Example 4(h): To 10 gm(19.0milimole) of the compound 3-Ketal Bisnordiene Tosylate (4) obtained in example 3 dissolved in 50 ml tetrahydrofuran was added catalyst cuprous iodide 0.1gm followed by simultaneous addition of 2.0 mole equivalent of isopentyl magnesium bromide solution in 0.5M THF, stirred till the TLC indicated the completion of reaction. The reaction mass was cooled to 10°C. Quenched the reaction mass with 10% ammonium chloride solution in 50 ml water and then extracted in Toluene 50 ml. The entire organic layer was then evaporated under vacuum to obtain the residue 3-Ketal 4,6- Cholestadiene (5).
Yield: 3.0gm; Percentage Yield: 75%
HPLC purity: 85%
The residue was crystalized using Toluene
The residue was further crystallized in toluene 10 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 5 ml, dry the filtered product
Yield: 1.1 gm; Percentage Yield: 13%
HPLC purity: 90%
The compound 3-Ketal Bisnordiene mesylate (4’)can be converted to the compound (5) by the process illustrated above.
Example 5: Preparation of Cholest-4,6-diene-3-one (6)
General Procedure:
3-Ketal 4,6- Cholestadiene (5) was treated with p-Toluene sulphonic acid at about 0.62 mole equivalence at room temperature to obtain Cholest-4,6-diene-3-one (6).

Example 5(a): To the 100 gm compound 3-Ketal 4,6- Cholestadiene (5) obtained from example 4 was added 25 gm (131.4milimole) para toluene sulphonic acid monohydrate in 100 ml water and stirred the mass for 3-8 hrs till TLC indicated completion of the reaction. The mixture was washed with 200ml of water and then extracted in 1000 ml of ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum to obtain the residue Cholest-4,6-diene-3-one (6).
Yield: 80 gm; Percentage Yield: 89%
HPLC purity: 87%

Example 5(b): To 5.0 gm (10.62 millimole) of the compound 3-Ketal 4,6- Cholestadiene (5) was added 50 ml of ethyl acetate, 2.5 ml HCl and stirred the mass for 3-8 hrs till TLC indicated completion of the reaction. The reaction mass was then washed with 20ml of water and extracted in 20 ml of ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum to obtain the residue Cholest-4,6-diene-3-one (6).
Yield: 3.9 gm; Percentage Yield: 87%
HPLC purity: 82%
The residue was crystallized with Acetone
The residue was further crystallized in Acetone 10 ml stir at 25-30°C chill to 5-10°C filter it wash by chill Acetone 5 ml, dry the filtered product
Yield: 1.5 gm; Percentage Yield: 33%
HPLC purity: 95%

Example 5(c): To 50 gm (106.21 millimole) of the compound 3-Ketal 4,6- Cholestadiene (5) was added 100 ml of ethyl acetate, 25 ml HC1 and the mixture was stirred for 3 hrs till TLC indicated completion of the reaction. The mass was washed with 20ml of water and extracted in 20ml ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum and residue to obtain the residue Cholest-4,6-diene-3-one (6).
Yield: 41 gm, Percentage Yield: 93%
HPLC purity: 80%
The residue was crystallized from methanol.
The residue was further crystallized in methanol 100 ml stir at 25-30°C chill to 5-10°C filter it wash by chill methanol 25 ml, dry the filtered product
Yield: 30gm; Percentage Yield: 67%
HPLC purity: 90%

Example 5(d): To 50 gm (106.21 millimole) of the compound 3-Ketal 4,6- Cholestadiene (5) was added 100 ml Toluene, 25 ml HCl and the mixture was stirred for 3 hrs till TLC indicated completion of the reaction. The mixture was then washed with 20ml of water and extracted in ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum to obtain the residue Cholest-4,6-diene-3-one (6).
Yield: 40 gm; Percentage Yield: 89%
HPLC purity: 85%

Example 5(e): To 50 gm (106.21 millimole) of the compound 3-Ketal 4,6- Cholestadiene (5) was added 100 ml acetone, 25 ml HCl and the reaction mixture was stirred for 3 hrs till TLC indicated completion of the reaction. The mixture was then washed with 20ml of water and then extracted in 20 ml of ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum to obtain the residue Cholest-4,6-diene-3-one (6).
Yield: 38 gm; Percentage Yield: 85%
HPLC purity: 86%

Example 5(f): To 50 gm (106.21 millimole) of the compound 3-Ketal 4,6- Cholestadiene (5) was added 100 ml methanol, 25 ml HCl. The reaction mixture was stirred for 3 hrs till TLC indicated completion of the reaction. The mixture was then washed with washed with 50ml of waste and then extracted in 20ml ethyl acetate. The entire ethyl acetate layer was then evaporated under vacuum to obtain the residue Cholest-4,6-diene-3-one (6).
Yield: 36 gm, Percentage Yield: 80%
HPLC purity: 85%

Example 6: Preparation of 3-Acetoxy- Cholest-3,5-diene (7).
General procedure:
Cholest-4,6-diene-3-one (6) was treated with acylating agents to form enol esters, acetylating agents in an amount of 11.34 to 22.68 mole equivalence, preferably 11.34 mole equivalence in presence of acid catalyst at 100-110oC to yield 3-Acetoxy- Cholest-3,5-diene(7).

Example 6(a): 100 gms (261 millimole) of Cholest-4,6-diene-3-one (6) obtained from example 5 was suspended in 500gm (2938 millimole) of acetic anhydride and 100 gm(1274 millimole) of acetyl chloride at 25-35°C. The reaction mass was stirred for 6-8 hours at 105-110°C till the TLC analysis indicated the absence of the starting material. Cooled the reaction mass to ambient temperature. Quenched the reaction mass in ice cold water solution followed by addition of 500ml water and finally extracted with 500 ml of Dichloromethane. Washed the organic layer with 250 ml of 8% sodium bicarbonate solution. The dichloromethane layer was evaporated to get the residue 3-Acetoxy- Cholest-3,5-diene(7).
Yield: 90 gm; Percentage Yield: 81%
HPLC purity: 82%.
The residue was purified with acetone.
The residue was further crystallized in Acetone 200 ml stir at 50-60°C chill to 10°C filter it wash by chill Acetone 50 ml, dry the filtered product
Yield: 50gm; Percentage Yield: 45%
HPLC purity: 91%

Example 6(b): 50 gms (130 millimole) of Cholest-4,6-diene-3-one (6) was suspended in 100 gm (998.8 millimole) isopropenyl acetate and 1 ml of sulphuric acid at 25-35°C. The reaction mass was stirred for 12-18 hours at 100°C till the TLC analysis indicated the absence of starting material. Cooled the reaction mass to ambient temperature. Quenched the reaction mass in ice cold water solution followed by extraction with 500 ml Dichloromethane and finally washing with 50 ml of 10% sodium bicarbonate solution. The dichloromethane layer was evaporated to get residue 3-Acetoxy- Cholest-3,5-diene(7).
Yield:.52.0 gm; Percentage Yield: 94%;
HPLC purity: 80%
The residue obtained was further isolated from silica column chromatography with 5% acetone in Toluene as the eluent.
Yield: 20 gm; Percentage Yield: 36%
HPLC purity: 88%

Example 6(c): 1.0 gm (2.6 millimole) of Cholest-4,6-diene-3-one (6) was suspended in 10 gm (9.9 millimole) acetic anhydride and 5 gm of acetyl chloride at 25-35°C. The reaction mass was stirred for 6-8 hours at 100°C till the TLC analysis indicated the absence of starting material. Cooled the reaction mass to ambient temperature. Quenched the reaction mass in ice cold water solution followed by extraction with Dichloromethane and finally washed with 50 ml of 10% sodium bicarbonate solution. The dichloromethane layer was evaporated to get residue 3-Acetoxy- 3,5,7 cholesta triene (7).
Yield: 1.0 gm; Percentage Yield: 90%
The residue was crystalized with isopropyl alcohol.
Yield: 0.5gm; Percentage Yield: 45%
HPLC purity: 90%

Example 6(d): 1.0 gm(2.6 millimole) of Cholest-4,6-diene-3-one (6) was suspended in 10gm (44.20 millimole) Benzoic anhydride and 5 gm (35.56 millimole ) of benzoyl chloride at 25-35°C. The reaction mass was stirred for 6-8 hours at 100°C till the TLC analysis indicated the absence of starting material. Cooled the reaction mass to ambient temperature. Quenched the reaction mass in ice cold water solution followed by extraction with ethyl acetate and finally washed with 50 ml of 10% sodium bicarbonate solution. The dichloromethane layer was evaporated to get residue 3-Acetoxy- 3,5,7 cholesta triene (7).
Yield: 1.1 gm; Percentage Yield: 99%
HPLC purity: 79%
The residue was crystallised from ethanol.
The residue was further crystallized in ethanol 10 ml stir at 25-30°C chill to 5-10°C filter it wash by chill ethanol 5 ml, dry the filtered product
Yield: 0.4gm; Percentage Yield: 36%
HPLC purity: 90%

Example 6(e): 1.0 gm (2.6 millimole) of Cholest-4,6-diene-3-one (6) was suspended in 10 gm (76.86 millimole) propionic anhydride, 5gm(54.04) of propionyl chloride at 25-35°C. The reaction mass was stirred for 6-12 hours at 100°C till the TLC analysis indicated the absence of starting material. Cooled the reaction mass to ambient temperature, quenched the reaction mass in ice cold water solution followed by extraction with Dichloromethane and finally washed with 50 ml of 10% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue 3-Acetoxy- 3,5,7 cholesta triene (7).
Yield: 0.8gm; Percentage Yield: 72 %
HPLC purity: 75%
The residue was crystalized from isopropyl alcohol.
The residue was further crystallized in isopropyl alcohol 10 ml stir at 25-30°C chill to 5-10°C filter it wash by chill isopropyl alcohol 5 ml, dry the filtered product
Yield: 0.5gm; Percentage Yield: 45%
HPLC purity: 90%

Example 6(f): 1.0 gm (2.6 millimole) of Cholest-4,6-diene-3-one (6) was suspended in 10 gm (9.9 millimole) Isobutyric anhydride, 5 gm(63.21 millimole) of Isobutyl chloride at 25-35°C. The reaction mass was stirred for 6-8 hours at 100°C till the TLC analysis indicated the absence of starting material. Cooled the reaction mass to ambient temperature, quenched the reaction mass in ice cold water solution followed by extraction with Dichloromethane and finally washed with 50 ml of 10% sodium bicarbonate solution. The dichloromethane layer was evaporated to get residue 3-Acetoxy- 3,5,7 cholesta triene (7).
Yield: 1.0 gm; Percentage yield: 85%
HPLC purity: 80%

Example 6(g): 1.0 gm (2.6 millimole) of Cholest-4,6-diene-3-one (6) was suspended in 10 gm (47.61 millimole) Trifluroacetic anhydride, 5 gm(37.74 millimole) of trifluroacetyl chloride at 25-35°C. The reaction mass stirred for 12-24 hours at 100°C till the TLC analysis indicated the absence of starting material. Cooled the reaction mass to ambient temperature, quenched the reaction mass in ice cold water solution followed by extraction with Dichloromethane and finally washed with 50 ml of 10% sodium bicarbonate solution. The dichloromethane layer evaporated to get residue 3-Acetoxy- 3,5,7 cholesta triene (7).
Yield: 1.1 gm; Percentage yield: 90%
HPLC purity: 88%

Example 7: Preparation of 7-dehydrocholesterol (7-DHC)
General Procedure:
3-Acetoxy- Cholest-3,5-diene(7) obtained from example 6 was treated with in- situ generation of calcium borohydride (reacting sodium borohydride 2.44 mole equivalence with calcium chloride anhydrous 1 mole equivalents ) at 0-5oC for 4-12 hours to yield 7 Dehydrocholesterol as major product and Epi -7 -Dehydrocholesterol as side product.
Alternately, 3-Acetoxy- Cholest-3,5-diene(7) obtained from example 6 can be reduced directly using suitable reducing agent and carrying out the process as described above.

Example 7(a): To 60 gm (540.6 millimole) of calcium chloride was charged absolute ethanol (600 ml) and stirred. Cooled the reaction mass to 5-10oC followed by slow addition of 50 gm(1321 millimole) of sodium borohydride and allowed to stir for 30 min at 5-10oC. This was followed by slow addition of 100 gm (235 millimole ) of 3-Acetoxy- Cholest-3,5,7-triene(7) dissolve in 100ml MDC at 0-5°C, then stirred at 0-5oC for 4-12 hrs till TLC indicated completion of the reaction. Quenched the reaction mass in 1.0 lit of ice cold water and extracted with1.0 lit Dichloromethane. Then washed with 250 ml of 50% acetic acid to yield crude product 7-DHC.
Yield: 84 gm, Percentage Yield: 96%
HPLC purity: 65% ; epi-7Dehydrocholetserol 10 %
Purification:
Dissolved the above crude in 250 ml of 20% toluene in methanol solution. Heated to 65°C and maintained the temperature for 30 minutes. Allowed to cool to 25-30°C gradually, chilled to 10-15°C, filtered and washed with 20ml methanol. Dried the solid product under vacuum at 50°C.
Yield: dry weight 40 gm; Percentage Yield: 44 %
HPLC purity: 96% ; Epi- 7- Dehydrocholesterol: 2%

Example 7(b): Charged 60gm calcium chloride to ethanol (300 ml), cooled to 0-5°C, then slowly added sodium borohydride 50 gm(1321 millimole) and allowed to stir for 30 min at 0-5oC. 60gm (141 millimole ) of the compound 3-Acetoxy-Cholest-3,5-diene(7) dissolved in 100 ml methylene dichloride (MDC) was slowly added at 0-10 °C for 12 hrs and the until reaction compliance was checked on TLC. After completion of the reaction the reaction mass was quenched in 1.0 lit ice cold water and extracted with 1000 ml DCM and finally washed with 250 ml of 2N HCl solution to yield crude product 7-DHC.
Yield: 80 gm; Percentage Yield: 88%
HPLC purity: 70% , epi-7dehydrocholestrol 10 %.
Purification by column chromatography:
Dissolved the crude in toluene and loaded on packed 60-200 mesh size silica column in Toluene. Eluted with 5% Acetone in Toluene and elute separation analysed by TLC to separate the Epi-7-dehydrocholesterol (8 gm)
Final main fraction crystalized in 200 ml methanol;

Yield: Dry weight 50 gm; Percentage Yield: 55%
HPLC purity 96.5%,

Example 7(c): To 6 gm (54.06 millimole) of calcium chloride was charged methanol (100 ml), stirred, cooled the reaction mass to 5-10oC, then slowly added 5.0 gm(132.1 millimole) sodium borohydride and allowed to stir for 30 min at 40-45oC. This was followed by slow addition of 10 gm (23.58 millimole ) of compound 3-Acetoxy-Cholest-3,5-diene(7) dissolved in 10 m Toluene at 40-45°C then stirred for 12-18 hrs and the reaction completion checked on TLC. After the reaction, the reaction mass was quenched in ice cold water, extracted with 50 ml Toluene and washed with 20 ml of 2 N HCl solution to yield crude product 7-DHC.
Yield: 3.0 gm; Percentage Yield: 55%
HPLC purity: 65%; Epi -7-Dehydrocholesterol: 25%
The final pure compound was obtained by column chromatography as described in example 7(b).
Yield: 1.2 gm; Percentage Yield: 12%

Example 7(d): To 100 ml of methanol, stirred, cooled to 5-10oC was slowly added 5.0 gm(132.1 millimole) sodium borohydride and allowed to stir for 30 min at 0-10oC. This was followed by slow addition of 10 gm (23.58 millimole) of compound 3-Acetoxy-Cholest-3,5-diene(7) dissolved in 10 ml Toluene at 0-10°C, then stirred for 12-18 hrs and the reaction completion checked on TLC. After completion of the reaction, the reaction mass was quenched in ice cold water, extracted with 50 ml Toluene, washed with 20 ml of 2N HCl solution to yield crude product 7-DHC.
Yield: 3.0 gm; Percentage Yield: 92.%
HPLC purity 65% ; Epi- 7 -Dehydrocholesterol 20%

The final purified 7-DHC was obtained by column chromatography as described in example7(b).
Yield: 1gm 10%

Example 7(e): To 100 ml of ethanol, stirred, cooled to 5-10oC was slowly added sodium triacetoxyborohydride 5.0 gm(23.59 millimole) and allowed to stir for 30 min at 0-10oC. This was followed by slow addition of 10 gm (23.58 millimole) of compound 3-Acetoxy-Cholest-3,5-diene(7) dissolved in 10 ml toluene at 0-10 °C, then stirred for 12-18 hrs and the reaction completion checked on TLC. After completion of the reaction, the reaction mass was quenched in ice cold water and extracted with 50 ml Toluene. Washed with 20 ml of 2N HCl solution to yield crude product 7-DHC.
Yield: 6.0 gm; Percentage Yield: 66.%
HPLC purity: 65%; Epi- 7- Dehydrocholesterol 25%

Example 7(f): To 100 ml of ethanol, stirred, cooled the mass to 5-10oC followed by slowly adding lithium borohydride 5.0 gm(210.26 millimole) and allowed to stir for 30 min at 0-10oC. 10 gm (23.58 millimole ) of 3-Acetoxy-Cholest-3,5-diene(7) dissolved in 10 ml Toluene was slowly added to the mixture at 0-10°C and then stirred for 12-18 hrs.The reaction completion was checked on TLC. After completion of the reaction the reaction mass was quenched in ice cold water and extracted with 50 ml Toluene. Washed with 20 ml 2N HCl solution to yield crude product 7-DHC.
Yield: 6.0 gm; Percentage Yield: 66 %
HPLC purity: 68% ;Epi- 7 -Dehydrocholesterol 12%.
Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be limited by the claims.
, Claims:
1. An industrially viable process for synthesis of 7-dehydrocholesterol (7-DHC) from bisnoralcohol comprising;
(i) Oxidizing bisnoralcohol (1) with p-chloranil in presence of solvent to (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one (2);

(ii) Protecting the 20-hydroxyl group of (20S)-20-hydroxymethyl-pregna-4,6-dien-3-one (2) in presence of acid scavenger and solvent to obtain (20S)-20-tosyloxymethyl-pregna-4,6-dien-3-one (3) or (20S)-20-mesyloxymethyl-pregna-4,6-dien-3-one (3’)

(iii) Protecting the ketonic group of compound (3) or (3’) with a protecting agent in presence of alkyl ester of orthoformic acid and weak acid to obtain 3-Ketal Bisnoralcohol Tosylate (4) or 3-Ketal bisnordiene mesylate (4’);

(iv) Coupling 3-Ketal Bisnoralcohol Tosylate (4) or 3-Ketal Bisnoralcohol Mesylate (4’) with Grignard reagent in presence of Cuprous (I) catalyst and the solvent to yield 3-Ketal 4,6- Cholestadiene (5);

(v) Deprotecting 3-Ketal 4,6- Cholestadiene (5) in presence of acid and water to obtain Cholest-4,6-diene-3-one (6);

(vi) Acylating Cholest-4,6-diene-3-one (6) with acylating agent in presence of acid catalyst to obtain 3-Acetoxy- Cholesta-3,5.7-Triene(7);

(vii) Reducing 3-Acetoxy- Cholest-3,5-diene(7) with reducing agent and the solvent to obtain 7-dehydrocholesterol as major and Epi -7 -Dehydrocholesterol as side product.

2. The process as claimed in claim 1, wherein, the process step (i) is carried out at a temperature in the range of 40oC-70oC and the solvent is selected from C1-C6 straight or branched alcohol, aromatic hydrocarbon selected from toluene, halogenated hydrocarbons alone or mixtures thereof.

3. The process as claimed in claim 1, wherein, the process step (ii) is carried out at ambient temperature; the tosylating or mesylating agent is selected from para toluene sulphonyl chloride or methane sulphonyl chloride; the acid scavenger is selected from aliphatic or aromatic base which include but is not limited to triethylamine, di isopropyl ethyl amine, pyridine or imidazole alone or mixtures thereof; the solvent is selected from halogenated hydrocarbons, aromatic or aliphatic hydrocarbons, esters, amines alone or mixtures thereof.

4. The process as claimed in claim 1, wherein, the process step (iii) is carried out at ambient temperature; the ketone protecting agent is selected from ethylene glycol or propane1,3 diol; the alkyl ester of orthoformic acid is selected from trimethyl orthoformate or triethyl orthoformate; the acid is selected from para toluene sulphonic acid monohydrate; the solvent is selected from aliphatic or aromatic hydrocarbons which include but is not limited to n-hexane, n-heptane, toluene; halogenated hydrocarbons, ethers alone or mixtures thereof.

5. The process as claimed in claim 1, wherein, for the process step (iv) the Grignard reagent is selected from alkyl magnesium halide such as isopentyl bromide; the catalyst selected from Cu(1) iodide, Cu(1) bromide or Cu(1) chloride, Cu(I) bromide dimethyl sufide complex; the solvent is selected from THF, 2- methyl tetra hydro furan, methyl-tert butyl ether; diethyl ether, isopropyl ether alone or mixtures thereof.

6. The process as claimed in claim 1, wherein, for the process step (v), the acid is selected from organic or inorganic acids which include but is not limited to para toluene sulphonic acid, HCl; the solvent is selected from lower alcohols, esters, ketone, aromatic hydrocarbon alone or mixtures thereof.

7. The process as claimed in claim 1, wherein, the process step (vi) is carried out at the temperature in the range of 100-110oC; the acylating agent is selected from mixture of acetic anhydride and acetyl chloride, isopropenyl acetate and sulphuric acid, benzoic anhydride and benzoyl chloride, propionic anhydride and propionyl chloride, isobutyric anhydride and isobutyl chloride, trifluroacetic anhydride and trifluroacetyl chloride; the solvent is selected from hydrocarbons, halogenated hydrocarbons, esters, ketones alone or mixtures thereof.

8. The process as claimed in claim 1, wherein, the reducing agent for step (vii) comprises in-situ generation of calcium borohydride by adding the alkali borohydrides selected from sodium borohydride, lithium borohydride, sodium triacetoxyborohydride, lithium borohydride to the cooled solution of calcium chloride in alcohol at 0-10oC.

9. The process as claimed in claim 1, wherein, the reducing agent for step (vii) is selected from alkali borohydrides selected from sodium borohydride, lithium borohydride, sodium triacetoxyborohydride or lithium borohydride.

10. The process as claimed in claim 1, wherein the solvent for step (vii) is selected from lower alcohols which include but is not limited to ethanol, methanol, IPA, t-butanol alone or mixtures thereof.

11. The process as claimed in claim 1, wherein the intermediates and the product obtained may be purified by crystallization from the solvent or by column chromatography.