Field of the invention:
The present invention provides a process for the preparation of D-glucitol, 1,5-anhydro-l-c-[4-chloro-3-[[4-[[(3,S)-tetrahydro-3-furanyl]oxy]phenyl]methyl]phenyl]-, (IS) and its polymorphs represented by following structural formula-1 thereof.
Background of the invention:
D-glucitol, l,5-anhydro-l-C-[4-chloro-3-[[4-[[(3,S)-tetrahydro-3-furanyl]oxy] phenyl]methyl]phenyl]-, (IS) genetically known as "Empagliflozin" which is a sodium-glucose co-transporter 2 (SGLT2) and this drug product used as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. It is marketed by Boehringer under the brand name Jardiance® and it is available in 10 mg and 25 mg strengths as tablet dosage forms.
US pat. No. 7,579,449 discloses Empagliflozin product and also a process for the preparation thereof comprising 4-bromo-l-chloro-2-(4-methoxybenzyl)-benzene reacted with tribromoborane in presence of dichloromethane to produce 4-(5-bromo-2-chloro-benzyl)-phenol which is reacted with t-butyl dimethyl silyl chloride in dichloromethane in presence of triethylamine and dimethylaminopyridine to get [4-(5-bromo-2-chloro-benzyl)-phenoxy]-tert-butyldimethyl-silane which is further reacted with n-BuLi in tetrahydrofuran followed by condensation with 2,3,4,6-tetrakis-0-(trimethylsilyl)-D-glucopyranone. The resulting solution is reacted with MsOH in MeOH followed by reduction with triethylsilylhydride and boron trifluoride etherate and acylated with acetic anhydride/pyridine in dichloromethane followed by treating with KOH in MeOH to produce pentahydroxy intermediate. This pentahydroxy intermediate is reacted with tetrahydrofuran-3-yl (S)-toluene-4-sulphonate in presence of caesium carbonate in dimethylformamide to produce the compound of formula-1.
Handling of tetrahydrofuran-3-yl (S)-touene-4-sulphonate intermediate compound is

very difficult in the synthesis of Empagliflozin as it mostly exist as unstable residue and accordingly reactions become challenging in the synthesis of Empagliflozin. Hence, this process is not suitable for industrial scale synthesis of Empagliflozin.
The above prior art process also suffered from very low yield of Empagliflozin due to reacting of pentahydroxy intermediate with tetrahydrofuran-3-yl (S)-toluene-4-sulphonate and also involves the use of hazardous BBr3 as it reacts violently and decomposes to toxic compounds when on contacting with moisture.
US pat. No. 7,772,191 discloses a process for the preparation of D-glucitol, 1,5-anhydro-l-C-[4-chloro-3-[[4-[[(3,S)-tetrahydro-3-furanyl]oxy]phenyl] methyl] phenyl]-, (IS) of formula-1. The process is as follows:
The above prior art process involves the use of BuMgCl which is extremely flammable and will cause for flash fire or ignite explosively. Hence, the handling of BuMgCl is very dangerous and will not be suitable for industrial scale preparations.
Hence, there is a significant need in the art to develop an alternate process for the preparation of Empagliflozin which is simple, cost effective and liable for industrial scale preparation methods.
The present inventors have developed an improved process for the preparation of Empagliflozin which will fulfill the all deficits in prior art processes and also developed a novel polymorph of Empagliflozin and its process for the preparation thereof. Brief description of the invention
The first aspect of the present invention is to provide a process for the preparation of D-glucitol, l,5-anhydro-l-C-[4-chloro-3-[[4-[[(3,S)-tetrahydro-3-furanyl]oxy]phenyl]methyl] phenyl]-, (IS) compound of formula-1.
The second aspect of the present invention is to provide polymorph form-M of Empagliflozin.
The third aspect of the present invention is to provide a process for the preparation of

polymorph form-M of Empagliflozin.
The fourth aspect of the present invention is to provide Empagliflozin-L-proline crystalline complex and its process for preparation thereof.
The fifth aspect of the present invention provides the compound of general formula-9 and process for its preparation thereof.
wherein, R' is same as defined hereinafter. Brief description of the drawings
FIG. 1: illustrates a characteristic PXRD pattern of polymorph form-M of Empagliflozin
compound of formula-1.
FIG. 2: illustrates a characteristic PXRD pattern of amorphous form of Empagliflozin
according to examples 11 and 12.
FIG. 3: illustrates a characteristic PXRD pattern of solid dispersion of Empagliflozin
according to examples 13 and 14.
FIG. 4: illustrates a characteristic PXRD pattern of Empagliflozin-L-proline crystalline
complex of Form-I.
FIG. 5: illustrates a characteristic PXRD pattern of Empagliflozin-L-proline crystalline
complex of Form-II.
FIG. 6: illustrates a characteristic PXRD pattern of Empagliflozin-L-proline crystalline
complex of Form-Ill.
FIG. 7: illustrates a characteristic PXRD pattern of Empagliflozin-L-proline crystalline
complex of Form-IV.
Detailed description of the invention:
The term "suitable solvent" used in the present invention refers to "hydrocarbon solvents" such as n-hexane, n-heptane, cyclohexane, petroleum ether, benzene, toluene, xylene and the like; "ether solvents" such as dimethyl ether, diisopropyl ether, diethyl ether, methyl tert-butyl ether, 1,2-dimethbxy ethane, tetrahydrofuran, 1,4-dioxane and the like;

"ester solvents" such as methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate and the like; "polar-aprotic solvents such as dimethylacetamide (DMAc), dimethylformamide (DMF), dimethylsulfoxide (DMSO), N-methylpyrrolidone (NMP) and the like; "chloro solvents" such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and the like; "ketone solvents" such as acetone, methyl ethyl ketone, methyl isobutyl ketone and the like; "nitrile solvents" such as acetonitrile, propionitrile, isobutyronitrile and the like; "alcoholic solvents" such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol and the like; "polar solvents" such as water or mixtures thereof.
As used herein the present invention, the term "suitable base" refers to inorganic base or organic base. The inorganic base selected from alkali or alkaline hydroxides such as sodium hydroxide or potassium hydroxide and the like; alkali or alkaline carbonates such as sodium carbonate or potassium carbonate, alkali or alkaline bicarbonates such as sodium bicarbonate or potassium carbonate; alkali or alkaline alkoxides such as sodium methoxide or potassium methoxide; The organic base selected from dimethylaminopyridine (DMAP), triethylamine (TEA), diisopropylethylamine (DIPEA), methylamine, butylamine and the like.
According to some embodiments, the hydroxy protecting agents are selected from R OC(0)-X, wherein R is alkyl of C1-C5 carbons and X is halogen such as CI, Br (for example, carboethoxy chloride, carbomethoxy chloride and t-butoxycarbonyl chloride); optionally substituted ArOC(0)-X, wherein Ar is an aryl group such as phenyl, benzyl (for example, benzyloxy carbonyl chloride and p-methoxybenzyloxycarbonyl bromide); RC(0)-X such as, acetyl chloride, and propionyl chloride and the like.
According to some embodiments, the hydroxy protecting group (Pg) is selected from -C(0)OR, such as, for example, carboethoxy, carbomethoxy and t-butoxycarbonyl; optionally substituted -C(0)OAr, such as, for example, benzyloxy carbonyl and p-methoxybenzyloxycarbonyl; optionally substituted -Ar(Ci-C3)alkyl such as, for example, benzyl, phenethyl, p-methoxybenzyl, 2,3-dimethoxybenzyl, 2,4-dimethoxybenzyl and 9-fluorenylmethyl; optionally substituted ArC(O)-, such as, for example, benzoyl; C1-C6 alkanoyl, such as, for example, acetyl, and propionyl.

The first aspect of the present invention provides an improved process for the preparation of D-glucitol, l,5-anhydro-l-C-[4-chloro-3-[[4-[[(3,S)-tetrahydro-3-furanyl]oxy] phenyljmethyl] phenyl]-, (IS) compound of formula-1, comprising the steps of:
a) Reducing the compound of general formula-2 using a suitable reducing agent in
presence of metal catalyst in a suitable solvent to provide the compound of general
formula-3;
wherein, the metal catalyst is TiCU; R is an alkyl group having C1-C5 carbon atoms; X is a halogen atom selected from bromo or iodo. b) reacting the compound of general formula-3 with the compound of formula-4 in presence of suitable organolithium reagent followed by treating with suitable acid in suitable solvent to provide the compound of general formula-5;
wherein, Ri is hydrogen or alkyl group having C1-C5 carbon atoms.
c) optionally isolating the compound of general formula-5;
d) reducing the product of step-b) or step-c) with a suitable reducing agent in a suitable solvent to provide the compound of general formula-6;
e) optionally, isolating the compound of general formula-6;

f) reacting the product of step-d) or step-e) with a suitable protecting agent in presence of a suitable base in suitable solvent to provide the compound of general formula-7;
wherein, Pg is a protecting group, g) reacting the compound of general formula-7 with suitable thiol reagent in presence of a suitable Lewis acid catalyst to provide the compound of general formula-8;
h) coupling the compound of general formula-8 with the compound of general formula-9 in presence of a suitable base in a suitable solvent to provide the compound of general formula-10;
wherein, R' refers to aryl or alkyl sulfonyl group which is substituted with one or more electron withdrawing groups selected from NO2, -NH3+, -N(Ri)3, -CN, -CHO, -COOH, trifluoroalkyl, halogens wherein, Ri is alkyl having C1-C5 carbon atoms. Preferably phenyl group substituted with -NO2 in 2n or 4* position, i) deprotecting the compound of general formula-10 in presence of suitable base in a suitable solvent to provide the Empagliflozin of formula-1.

wherein, in step-a) the suitable reducing agent is selected from trialkylsilyl hydrides,
hydrogen gas in presence of Pd, Pt, Raney Ni, Fe and the like; the suitable metal catalyst is
TiCU; the suitable solvent is selected from halohydrocarbon solvents, ether solvents, ester
solvents, polar-aprotic solvents or the mixture of solvents thereof.
In step-b), the organolithium compound is selected from n-butyl lithium, t-butyl lithium and
the like; the suitable acid is selected from alkyl sulfonic acids, aryl sulfonic acids, mineral
acids; the suitable solvent is selected from alcohol solvents having C1-C5 carbon atoms.
In step-d), the suitable reducing agent is selected from trialkyl silylhydride such as
trimethylsilyl hydride, triethylsilylhydride, tributylsilylhydride and the like; the suitable
solvent is selected from acetonitrile, dimethylformamide, dimethylsulfoxide,
dimethylacetamide, dichloromethane, chlorobenzene, chloroform, toluene, xylene, benzene,
ethyl acetate, methyl acetate, propyl acetate, diethylether, tert-butylmethyl ether,
tetrahydrofuran or the mixture of solvents thereof.
In step-f), the suitable protecting agent is having formula R-C(0)-C1, wherein R is an alkyl
group having C1-C5 carbon atoms; the suitable base is selected from DMAP, TEA, DIPEA,
diethylamine, ammonia and the like; the suitable solvent is as defined above.
In step-g), the suitable thiol agent is selected from decanethiol, dodecane thiol, methanethiol,
ethanethiol, 1-propanethiol, 2-propanethiol, n-butanethiol, tert-butanthiol, furan-2-
ylmethanethiol; suitable Lewis acid is selected from aluminium trihalides such as AICI3,
AlBr3 and the like, boron trihalides such as BF3, BCI3; TiCU, FeCh, ZnCb.
In steps-f), h) & i), the suitable base is alkali or alkaline hydroxides, alkali or alkaline
carbonates, alkali or alkaline bicarbonates or alkali or alkaline alkoxides; the suitable solvent
is selected from alcohol solvents, chloro solvents, ketone solvents, polar aprotic solvents,
nitrile solvents, ester solvents, hydrocarbon solvents, ether solvents and polar solvents like
water or mixture thereof.

The preferred embodiment of the present invention provides a process for the preparation of Empagliflozin of formula-1, comprising the steps of:
a) Reducing (5-bromo-2-chlorophenyl)(4-methoxyphenyl)methanone of with triethylsilylhydride in presence of titanium tetrachloride in methylene chloride to provide 4-bromo-1 -chloro-2-(4-methoxybenzyl)benzene;
b) reacting 4-bromo- l-chloro-2-(4-methoxybenzyl)benzene of formula (3a) with (3i?,45',5i?,6i?)-3,4,5-tris((trimethylsilyl)oxy)-6-(((trimethylsilyl)oxy)methyl)tetra hydro-2//-pyran-2-one of formula (4) in presence of «-butylithium followed by treating with aqueous HC1 and water to provide (2^,37?,4,S',5)S',6i?)-2-(4-chloro-3-(4-methoxybenzyl)phenyl)-6-(hydroxymethyl)-2-hydroxytetrahydro-2//-pyran-3,4,5-triol;
c) reducing the product obtained in step-b) with triethylsilylhydride in presence of BF3.etherate to provide (25',3i?,4i?,55',6i?)-2-(4-chloro-3-(4-methoxybenzyl)phenyl)-6-(hydroxymethyl)tetrahydro-2//-pyran-3,4,5-triol;
d) reacting the product obtained in step-c) with aceticanhydride in presence of DMAP in methylene chloride to provide (2i?,3i?,4i?,5,S',6)S)-2-(acetoxymethyl)-6-(4-chloro-3-(4-methoxy benzyl)phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate;
e) reacting the product obtained in step-d) with dodecanethiol in presence of AICI3 to provide the (2R, 3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-hydroxybenzyl) phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate;
f) reacting the product obtained in step-e) with (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate in presence of potassium carbonate in dimethylformamide to provide (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-(((5)-tetrahydrofuran-3-yl)oxy)benzyl)phenyl)tetrahydro-2i7-pyran-3,4,5-trityl triacetate;
g) deprotecting the product obtained in step-f) to provide the compound of formula-1. The another embodiment of the present invention provides a process for the
preparation of Empagliflozin of formula-1, comprising the steps of:
a) Reacting the compound of general formula-7 with suitable thiol reagent in presence of a suitable Lewis acid catalyst to provide the compound of general formula-8;

b) reacting the compound of general formula-8 with the compound of general formula-9 in presence of a suitable base in a suitable solvent to provide the compound of general formula-10;
c) deprotecting the compound of general formula-10 in presence of suitable base in a suitable solvent to provide the Empagliflozin of formula-1.
wherein, in step-a), the suitable thiol reagent is selected from thiol or dithiol alcohol such as decanethiol, dodecane thiol, methanethiol, ethanethiol, 1-propanediol, 2-propanethiol, n-butanethiol, tert-butanthiol, ethandithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,3-butanedithiol, 1,4-butanedithiol; suitable Lewis acid is selected from aluminium trihalides such as AICI3, AlBr3 and the like, boron trihalides such as BCI3 and the like, TiCU, FeCb, ZnCb and the like; in step-b) the suitable base is selected from alkali or alkaline metal hydroxides, alkali or alkaline metal carbonates, alkali or alkaline metal bicarbonates, alkali or alkaline metal alkoxides; in step-c) the deprotection is carried out by using suitable base or suitable acid in a suitable solvent; in step-a) to step-c), the suitable solvent is selected from alcohol solvents; chloro solvents; ketone solvents; nitrile solvents; ester solvents; hydrocarbon solvents; ether solvents or mixture thereof.
The preferred embodiment of the present invention provides a process for the preparation of Empagliflozin, comprising:
a) Reacting (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-methoxybenzyl phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate with dodecanethiol in presence of AICI3 to provide (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-hydroxy benzyl)phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate;
b) reacting the product obtained in step-a) with (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate in presence of potassium carbonate in dimethylformamide to provide (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-(((5)-tetrahydrofuran-3-yl)oxy)benzyl)phenyl)tetrahydro-2i7-pyran-3,4,5-trityl triacetate;
c) deprotecting the product obtained in step-b) to provide the Empagliflozin of formula-1.

The another embodiment of the present invention provides dealkylation of the compound of general formula-7 with suitable thiol reagent in presence of a suitable Lewis acid catalyst to provide the compound of general formula-8.
The second aspect of the present invention provides polymorph form-M of Empagliflozin. Polymorph form-M of Empagliflozin is characterized by Powdered X-Ray Diffraction (PXRD) peaks at about 15.0, 18.1, 22.5 ± 0.2° of two-theta. Polymorph form-M is further characterized by PXRD having additional peaks at 3.6, 4.6, 6.8, 7.5, 16.3, 17.2, 20.5, 21.4, 23.8, 25.0 ± 0.2° of two-theta. Further, polymorph form-M of Empagliflozin is characterized by PXRD pattern as shown in figure-1.
The third aspect of the present invention provides a process for the preparation of polymorph form-M of Empagliflozin, comprising of:
a) Suspending Empagliflozin in a suitable solvent,
b) heating the reaction mixture of step-a) to a suitable temperature,
c) adding anti-solvent to the reaction mixture of step-b) at a suitable temperature,
d) stirring the reaction mixture of step-c) at a suitable temperature,
e) isolating polymorph form-M of Empagliflozin.
wherein, in step-a) the suitable solvent is selected from ester solvents, hydrocarbon solvents, polar aprotic solvents, alcohol solvents having C1-C5 carbon atoms, chloro solvents, or mixtures thereof; in step-b) the suitable temperature used is ranging from 30°C to 85°C; in step-c) the suitable anti-solvent is selected from hydrocarbon solvents, ether solvents; in step-c) and step-d), the suitable temperature is ranging from -50°C to -40°C; in step-e) the isolation is carried out by distilling off the solvent from the obtained reaction mixture from step-d) to afford the crystalline form-M of Empagliflozin.
The present invention provides a process for the preparation of amorphous form of Empagliflozin compound of formula-1, comprising of:
a) adding Empagliflozin to a suitable solvent,
b) stirring the reaction mixture of step-a) at a suitable temperature,
c) isolating amorphous form of Empagliflozin
wherein, in step-a) the suitable solvent is selected from alcohol solvents having C1-C5 carbon atoms, ester solvents, ketone solvents having C3-C5 carbon atoms, chloro solvents, or

mixtures thereof; in step-b) the suitable temperature is ranging from 25°C to the reflux temperature of the solvent used; in step-c) isolation can be carried out by the distillation under reduced pressure at a suitable temperature ranging from about 30-60°C.
The fourth aspect of the present invention provides Empagliflozin-L-proline crystalline complex.
The preferred embodiment of the present aspect is novel crystalline Forms-I, II, III and IV of Empagliflozin-L-proline and its process for preparation thereof.
Form-I of Empagliflozin-L-proline crystalline complex is characterized by PXRD having peaks at about 18.7, 19.9 and 22.3 ± 0.2° of 29 as illustrated in figure-3.
Form-II of Empagliflozin-L-proline crystalline complex is characterized by PXRD having peaks at about 4.6, 6.9, 9.7, 13.6, 15.9, 16.3, 17.3, 18.6, 18.9, 19.8, 20.8, 22.2, 22.6, 23.4, 27.3, 32.0, 33.4 ± 0.2° of 20 as illustrated in figure-4.
Form-Ill of Empagliflozin-L-proline crystalline complex is characterized by PXRD having peaks at about 4.1, 15.5, 18.2, 18.6, 19.8, 23.0, 31.9 and 33.7 ± 0.2°of 2 theta as illustrated in figure-5.
Form-IV of Empagliflozin-L-proline crystalline complex is characterized by PXRD having peaks at about 4.2, 8.5, 11.6, 12.8, 14.0, 15.6, 16.8, 17.1, 18.2, 18.7, 18.9, 19.9,21.0, 21.6, 22.2, 23.0, 24.4 ± 0.2° of 20 as illustrated in figure-6.
In yet another embodiment of the present invention provides a process for the preparation of Forms-I, II, III and IV of crystalline Empagliflozin-L-proline comprising, the following steps:
a) Suspending Empagliflozin and L-proline in one or more organic solvents;
b) heating to a suitable temperature;
c) stirring at suitable temperature;
d) isolating crystalline Empagliflozin-L-proline complex.
wherein, in step-a) the organic solvents are selected from hydrocarbon solvents, chloro solvents, ether solvents, cyclic ether solvents, ester solvents, alcohol solvents having C1-C5 carbon atoms or their mixtures thereof; in step-b) & step-c) the suitable temperature is ranging from 25-30°C to about 60°C to 65°C.

The fifth aspect of the present invention provides the compound of general formula-9.
wherein, R' is aryl or alkyl sulfonyl group which is substituted with one or more electron withdrawing groups selected from N02, -NH3+, -N(Ri)3, -CN, -CHO, -COOH, trifluoroalkyl, halogens wherein, Ri is alkyl group having C1-C5 carbon atoms. Preferably, phenyl group substituted with -N02 in the 2nd or 4th position.
The preferred embodiment of the present invention provides (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate compound.
The another preferred embodiment of the present invention provides solid compound of (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate.
The another aspect of the present invention provides a process for the preparation of compound of formula-9, comprising: reacting the (i?)-tetrahydrofuran-3-ol with compound of general formula-11 in presence of suitable base in suitable solvent to provide the compound of formula-9. The process is shown below:
wherein, R is same as defined above; the suitable base is organic or inorganic base is selected from DMAP, TEA, DIPEA, alkali or alkaline hydroxide, alkali or alkaline carbonates, alkali or alkaline bicarbonate or mixtures thereof. Prefarebly DMAP & TEA; the suitable solvent is selected from methylene chloride, methanol, ethanol, isopropanol, n-butanol, isobutanol, ethyl acetate, methyl acetate, propyl acetate, acetonitrile, dimethyl formamide, dimethylacetamide, diethyl ether, methyl tert-butyl ether, tetrahydrofuran or mixtures thereof.
The preferred embodiment of the present invention provides a process for the preparation of (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate of formula-9a, comprising:

reacting (i?)-tetrahydrofuran-3-ol with 4-nitrobenzene-l-sulfonyl chloride of formula-10a in presence of DMAP and TEA in methylene chloride.
The another preferred embodiment of the present invention provides a process for the preparation of (i?)-tetrahydrofuran-3ol, comprising: reacting (,S)-tetrahydrofuran-3-ol with/?-nitrobenzoic acid in presence of triphenylphosphine and diisopropyl azodicarboxylate in a suitable solvent followed by treating the obtained compound with a suitable base in a suitable solvent to produce (i?)-tetrahydrofuran-3-ol.
wherein, R' is same as defined above; the suitable solvent selected from ether solvents, nitrile solvents, chloro solvents, ester solvents, hydrocarbon solvents, alcohol solvents, polar aprotic solvents or mixtures thereof; the suitable base is organic or inorganic base is selected from DMAP, TEA, DIPEA, alkali or alkaline hydroxide, alkali or alkaline carbonates, alkali or alkaline bicarbonate or mixtures thereof.
PXRD analysis of the crystalline form-M and amorphous form of Empagliflozin were carried out using BRUKER-AXS D8 Advance X-Ray diffractometer using Cu-Ka radiation of wavelength 1.5406 A° and at continuous scan speed of 0.03°/min.
The process described in the present invention was demonstrated in examples illustrated below. These examples are provided as illustration only and therefore should not be construed as limitation of the scope of the invention: Examples:

Example-1: Preparation of (5-bromo-2-chlorophenyl)(4-methoxyphenyl)methanone
5-Bromo-2-chlorobenzoic acid (100 gm) and dichloromethane (500 ml) were charged into a clean and dry RBF at 25-30°C under nitrogen atmosphere and stirred for 5-10 min. at the same temperature. Dimethylformamide (5 ml) was added to the above formed reaction mixture and cooled to 0-5°C. To this cooled reaction mixture, oxalyl chloride (64.7 gms) was slowly added and stirred for 1 hr at 0-5°C under nitrogen atmosphere to get benzoyl chloride compound.
Anisole solution (55.0 gms of anisole dissolved in 200 ml of methylene chloride) and AICI3 (67.8 gms) were added to the above benzoyl chloride compound at 0-5°C and slowly raised the temperature of the reaction mixture to 25-30°C with stirred for 6 hours at same temperature. The obtained reaction mixture was quenched with aqueous HC1 solution and separated the organic and aqueous layers and extracted the aqueous layer with dichloromethane. The total organic layers were combined and washed with aqueous sodium carbonate solution and distilled off the solvent completely under reduced pressure and followed by co-distilled with isopropanol under reduced pressure to get a solid compound. The obtained solid compound was recrystallized from isopropanol (500 ml) at 70-75°C and cooled to get the title compound. (Yield: 124.3 g, M.R: 92-97°C) Example-2: Preparation of 4-bromo-l-chloro-2-(4-methoxybenzyl)benzene
(5-Bromo-2-chlorophenyl)(4-methoxyphenyl)methanone (100 gms) and methylene dichloride (800 ml) were charged into a clean and dry RBF at 0-5°C. To this reaction mixture, TiCU (174.8 gms) and triethylsilylhydride (TESH) (107.6 gms) were slowly added at 0-5°C and stirred for 15 min. at same temperature. The temperature of the reaction mixture was raise to 25-30°C and stirred for 4 hrs. at same temperature. Added obtained reaction mixture to chilled water (1000 ml) at 10-15°C and stirred for 30 min at 25-30°C. Separated the both organic, aqueous layers and extracted the aqueous layer with methylene chloride. The formed total organic layer was washed with 10% aqueous sodium carbonate solution and again with 10% aqueous sodium chloride solution. Distilled off the solvent completely under reduced pressure. Isopropanol (200 ml) and methanol (50 ml) were added to the above distillate and stirred for 30 min at 50-55°C. Cooled the reaction mixture to 0-5°C, filtered and dried the obtained compound to get the title compound. (Yield: 81.26 gms, M.R: 42-47°C)

Example-3: Preparation of (2^',3JR,4^',5^',6JR)-2-(4-chloro-3-(4-methoxybenzyl)phenyl)-6-(hydroxymethyl)-2-methoxytetrahydro-2H-pyran-3,4,5-triol
4-Bromo-l-chloro-2-(4-methoxybenzyl)benzene (100 gms) and tetrahydrofuran (1000 ml) were charged into a clean and dry RBF at 25-30°C. To the resulted reaction mixture, (3R, 4S,5R, 6i?)-3,4,5-tris((trimethylsilyl)oxy)-6-(((trimethylsilyl)oxy)methyl)tetrahydro-2i7-pyran -2-one (269 gms) was added at 25-30°C and cooled to about -75°C under nitrogen atmosphere and stirred for 20 min. Added N-butyl lithium (410 ml) to the reaction mixture at -75°C and stirred for 3 hrs at same temperature. A solution of methanesulfonic acid (153.7 gms) in methanol (500 ml) was added to the above reaction mixture at -75°C and raised the temperature of reaction mixture to 25-30°C and stirred for 16 hours at same temperature. Basify the obtained reaction mixture with 10% aqueous sodium carbonate solution and washed with n-heptane solvent. Separated the aqueous, organic layers and extracted the aqueous layer twice ethyl acetate. Combined the organic layers and washed with aqueous sodium chloride solution. Distill off the solvent completely from organic layer under reduced pressure to get the title compound. (Yield: 136.0 g)
Example-4: Preparation of (2^',3JR,4JR,5^',6JR)-2-(4-chloro-3-(4-methoxybenzyl)phenyl)-6-(hydroxymethyl)tetrahydro-2//-pyran-3,4,5-triol
(25',3i?,45',55',6i?)-2-(4-chloro-3-(4-methoxybenzyl)phenyl)-6-(hydroxymethyl)-2-methoxy tetrahydro-2//-pyran-3,4,5-triol (136 gms), dichloromethane (680 ml) and acetonitrile (680 ml) were charged into a RBF at 25-30°C and stirred for 15 min to get clear solution. Cooled the reaction mixture to 0-5°C and added boron trifluoride etherate (144 gms), triethylsilyl hydride (111.5 gms) followed by stirring for 1 hr at same temperature. Basified the obtained reaction mixture with aqueous sodium carbonate solution and stirred for 20 min at 0-5°C. Ethyl acetate (680 ml) was added to the above formed reaction mixture and raised the temperature of the reaction mixture to 25-30°C and stirred for 15 min at same temperature. Separated the organic, aqueous layers and extracted aqueous layer with ethyl acetate solvent. Combined the total organic layers and washed with aqueous sodium chloride solution. Distilled off the solvent completely from organic layer under reduced pressure to get the title compound. (Yield: 125 gms)

(25',3i?,4i?,55',6i?)-2-(4-chloro-3-(4-methoxybenzyl)phenyl)-6-(hydroxymethyl) tetrahydro-2//-pyran-3,4,5-triol (125 gms) dissolved in methylene dichloride (1000 ml) at 25-30°C. Added dimethylaminopyridine (6.6 gms) to the above resulted reaction mixture at 25-30°C. Acetic anhydride (146 gms) was added to the above reaction mixture and stirred for 4 hours at 25-30°C. Diluted the obtained reaction mixture with water and stirred for 30 min. Separated the organic and aqueous layers. Extracted the aqueous layer with methylene dichloride. The total organic layer was washed with aqueous sodium chloride solution, followed by with aqueous sodium carbonate solutions and finally with water. Distilled off the solvent completely from the organic layer under reduced pressure and co-distilled with methanol under reduced pressure. Added methanol (500 ml) to the above distillate and stirred for 1 hr at 70°C. Cooled the reaction mixture to 0-5°C and stirred for 2 hrs at same temperature. Filtered the obtained compound and washed with methanol solvent and dried to get the title compound. (Yield: 80 gms)
Example-6: Preparation of the (2R, 3R, 4R, SS, 6£)-2-(acetoxymethyl)-6-(4-chloro-3-(4-hydroxybenzyl) phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate
Aluminum chloride (94.85 gm) and dichloromethane (200 ml) were charged into a round bottom flask. Dodecanethiol (143 gms) was dissolved in the above resulted solution at 25-30°C and cooled the reaction mixture to 15-20°C. To this reaction mixture, a solution of (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-methoxybenzyl)phenyl)tetrahydro-2i7-pyran-3,4,5-triyl triacetate (100 gms dissolved in 200 ml of dichloromethane) added at 15-20°C and stirred for 3 hrs at 25-30°C. Chilled water (1000 ml) added to the above reaction mixture and stirred for about 15 mins at 25-30°C. Separated the organic and aqueous layers. The aqueous layer was extracted with dichloromethane. The total organic layer was washed with aqueous sodium carbonate solution and again washed with water. Distilled off the solvent completely from the organic layer under reduced pressure. The obtained compound was co-distilled with cyclohexane (100 ml). Cyclohexane (600 ml) was added to the above distillate and heated to 45-50°C and stirred for 45 min. at same temperature. Cooled the

reaction mixture to 25-30°C and stirred for 2 hrs. Filtered, washed the resulting compound with cyclohexane and dried to get the title compound. (Yield: 86.0 gms, M.R: 145-149°) Example-7: Preparation of (Y?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate
(5)-Tetrahydrofuran-3-ol (10 gms) was dissolved in THF (100 ml) at 25-30°C. Cooled the reaction mixture to 0-5°C, added triphenylphosphine (44.65 gms), /?-nitrobenzoic acid (18.96 gms) and stirred for 30 min at the same temperature. Diisopropyl azodicarboxylate (DIAD) (27.53 gms) was slowly added to the above reaction mixture at 0-5°C and stirred for 60 min at the same temperature. Distilled off the solvent completely from reaction mixture under reduced pressure at 45-50°C. Methanol (100 ml) was added to the above obtained distillate and stirred for 15 min at 0-5°C and K2CO3 (31.32 gms) was added to the reaction mixture and stirred for 30 min. Filtered the reaction mixture and washed with methanol. Distilled off the solvent completely from the filtrate under reduced pressure and cooled to 25-30°C. Add water (10 ml) to the above obtained solid at 25-30°C and stirred for 45 min. at the same temperature. Mixture of methylene chloride (50 ml) and cyclohexane (50 ml) was added to the above reaction mixture and stirred for 25 min. Separated the organic and aqueous layers. Mixture of methylene chloride (50 ml) and cyclohexane (50 ml) was added to the aqueous layer. Distilled off the total aqueous layer under reduced pressure at below 75-80°C and co-distillated with methylene chloride (20 ml). Add methylene chloride (100 ml) to the above distillate and cooled to 0-5°C. Triethylamine (22.97 gms) was added to the reaction mixture at 0-5°C and stirred for 25 min at same temperature. /^-Nitrobenzene sulfonyl chloride (25.15 gms) and dimethylaminopyridine (1.38 gms) were added to the reaction mixture at 0-5°C and stirred for 2 hrs at same temperature. Water was added to the reaction mixture with and separated the organic and aqueous layers. Organic layer was washed with aqueous HC1 solution followed by aqueous Na2CC>3 solution, water and finally with aqueous NaCl solution consecutively at 25-30°C. Distilled off the solvent from the reaction mixture at 40°C and co-distilled with methanol (30 ml). Add methanol (10 ml) to the above obtained compound at 25-30°C. Heated the reaction mixture to 60-65°C and stirred for 45 min at same temperature. Cooled the reaction mixture to 0-5°C and stirred for 45 min. at same temperature. Filtered the precipitated solid, washed with methanol and then dried to get the solid title compound. (Yield: 6.0 gms, Purity by HPLC: 99.93%. M.R: 82°C - 87°C)

Example-8: Preparation of (/?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate
(R)-3-Hydroxyfuran (100 gms) and dichloromethane (1000 ml) were charged into a clean and dry RBF at 25-30°C and stirred for 10 min at same temperature. To the resulted reaction mixture, dimethylaminopyridine (11.8 gms) and triethylamine (229 gms) were added and cooled to 0-5°C. 4-Nitro benzenesulfonyl chloride (301.0 gms) was added to the above reaction mixture and raised the temperature to 25-30°C and stirred for 4 hrs at same temperature. Water (500 ml) was added to the above reaction mixture and stirred for 20 min. and separate the aqueous and organic layers. The organic layer was washed with aqueous hydrochloride solution and followed by with aqueous sodium bicarbonate. Distilled the solvent completely from the solution. Co-distilled the obtained compound with methanol. The obtained compound was dissolved in methanol (500 ml) at 60-65°C and stirred for 1 hr. Cooled the reaction mixture to 0-5°C and again stirred for 2 hrs. Filtered, washed and dried obtained material to get the title compound as a solid.(Yield: 280.0 gms). Example-9: Preparation of (2tf,3^tf,5S,6^-2-(acetoxymethyl)-6-(4-chloro-3-(4-(((S)-tetrahydrofuran-3-yl)oxy)benzyl)phenyl)tetrahydro-2//-pyran-3,4,5-trityl triacetate
(2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-hydroxybenzyl)phenyl)tetra hydro-2//-pyran-3,4,5-triyl triacetate (100 gms) was dissolved in acetonitrile (1000 ml) at 25-30°C. To this reaction mixture, (R)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate (54.75 gms), potassium carbonate (125.88 gms) were added and heated the reaction mixture to 80°C and stirred for 8 hrs. Filtered the reaction mixture and washed with acetonitrile and distilled off the solvent completely under reduced pressure. Added dichloromethane (600 ml), dimethylaminopyridine (2.22 gms), aceticanhydride (37.16 gms) to the above obtained compound and stirred for 3 hrs at 25-30°C. Diluted the reaction mixture with water (500 ml) and again stirred for 15 min. The aqueous layer was extracted with dichloromethane. The organic layers were combined and washed with aqueous hydrochloride solution. The organic layer was washed with aqueous sodium carbonate solution and followed by again washed with water. Distilled off the solvent completely from the solution under reduced pressure. Methanol (400 ml) was added to the above distillate and heated to 65°C and stirred for 1 hr at same temperature to get the clear solution. Cooled the reaction mixture to 25-30°C and further cooled to 0-5°C stirred for 2 hrs at same temperature. Filtered, washed the obtained

compound with methanol and dried to get the title compound. (Yield: 95.8 gms, M.R: 150-
155°C)
Example-10: Preparation of Empagliflozin
The product of example-9 (100 gms) and methanol (800 ml) were charged into a RBF at 25-30°C. Added aqueous sodium hydroxide solution (154 gms dissolved in 100 ml of water) to the resulted reaction mixture and raised reaction mixture temperature to 65°C and stirred for 20 hrs at same temperature. Filter the formed reaction mixture with methanol Cooled the reaction mixture to 25-30°C and added water (1000 ml), ethyl acetate (1000 ml). Raised the reaction mixture temperature to 45-50°C and stirred for 45 mins at same temperature. Organic and aqueous layers were separated and distilled off the solvent completely from the organic layer under reduced pressure. Filtered and dried the obtained material to get the title compound. (Yield: 56.5 gms, MR: 147-150°C). Example-11: Preparation of polymorph Form-M of Empagliflozin
Empagliflozin (500 mg) and ethyl acetate (40 ml) were charged into a clean and dry RBF at 25-30°C. Raised the resulting reaction mixture temperature to 85°C and stirred for 15 min at same temperature. The obtained reaction mixture was added to chilled n-heptane solution (60 ml) at -55°C and stirred for 10 min at same temperature. Filtered the obtained material and dried to get the title compound. (Yield: 420 mg).
The obtained solid crystalline Form-M is characterized by PXRD having peaks at about 15.0, 18.1, 19.1, 22.5 ± 0.2° of 20 as illustrated in figure-1. Example-12: Preparation of amorphous form of Empagliflozin
Empagliflozin (500 mg) and acetone (10 ml) were charged into a clean and dry RBF at 25-30°C. Raised the resulting reaction mixture temperature to 50°C and stirred for 5 min at the same temperature. Filtered the resulting reaction mixture and the filtrate was taken into a clean and dry Buchi funnel and distilled off the solvent completely under reduced pressure followed by dried to afford the amorphous form of Empagliflozin. (Yield: 420 mg). The obtained amorphous form is characterized by PXRD pattern as illustrated in figure-2. Example-13: Preparation of amorphous form of Empagliflozin

Empagliflozin (500 mg) and ethyl acetate (10 ml) were charged into a clean and dry RBF at 25-30°C. Raised the reaction mixture temperature to 75-80°C and stirred for 5 min at same temperature. Filtered the resulting reaction mixture and filtrate was taken into clean and dry Buchi funnel and distilled off the solvent completely under reduced pressure and dried to afford the amorphous form of Empagliflozin. (Yield: 390 mg).
The obtained amorphous form is characterized by PXRD pattern as illustrated in figure-2.
Example-14: Preparation of solid dispersion of Empagliflozin
Empagliflozin (500 mg) and methanol (30 ml) were charged into a clean and dry RBF
at 25-30°C and stirred for 5 min at same temperature. Hydroxy propyl cellulose (FIPC) (500 mg) and dichloromethane (30 ml) were charged into another clean and dry round bottom flask at 25-30°C and stirred for 10 min at same temperature. The resulted reaction solution was added to the above methanolic Empagliflozin solution and stirred for 15 min at 60°C. Distilled off the solvent completely from the reaction mixture under the reduced pressure and dried the material to get the title compound (Yield: 380 mg).
The obtained solid dispersion was characterized by PXRD pattern as illustrated in figure-3.
Example-15: Preparation of solid dispersion of Empagliflozin
Empagliflozin (500 mg) and methanol (30 ml) were charged into a clean and dry RBF
at 25-30°C and stirred for 5 min at same temperature to get the clear solution. Cros-povidone and dichloromethane (30 ml) were charged into another clean and dry round bottom flask at 25-30°C and stirred for 10 min at same temperature to get the clear solution. The resulted solution was added to the above Empagliflozin solution at 60°C and stirred for 15 min at same temperature. Distilled off the solvent completely from the reaction mixture under reduced pressure and dried the material to get the title compound (Yield: 320 mg). The obtained compound was characterized by PXRD pattern as illustrated in figure-3. Example-16: Preparation of Empagliflozin-L-proline crystalline complex (Form-I)
Empagliflozin (500 mg) and L-proline (20 mg), isopropanol (5 ml), dichloromethane (5 ml), chlorobenzene (5 ml) and tetrahydrofuran (5 ml) mixture were charged into a clean and dry RBF at 25-30°C. Raised the resulting reaction mixture temperature to 60-65°C and stirred for 60 min at same temperature. Slowly cooled the reaction mixture to 25-30°C and

stirred for 5 hrs at same temperature. Filtered the obtained precipitated solid and dried to get the title compound (Yield: 380 mg).
The obtained Empagliflozin-L-proline crystalline complex (Form-I) is characterized by PXRD having peaks at about 18.7, 19.9 and 22.3 ± 0.2° of 20 as illustrated in figure-4. Example-17: Preparation of Empagliflozin-L-proline crystalline complex (Form-II)
Empagliflozin (2 gr) and L-proline (50 mg), ethanol (20 ml) and toluene (20 ml) were charged into a clean and dry RBF at 25-30°C. Raised the resulting reaction mixture temperature to 60-65°C and stirred for 7 hrs at same temperature. Filtered the obtained precipitated solid and dried to get the title compound (Yield: 1.4 gr).
The obtained Form-II is characterized by PXRD having peaks at 6.9, 9.7, 18.6, 18.9 ± 0.2° of
29 as illustrated in figure-5.
Example-18: Preparation of Empagliflozin-L-proline crystalline complex (Form-Ill)
Empagliflozin (2 gr) and L-proline (50 mg), isopropanol (5 ml) and dichloromethane (5 ml), chlorobenzene (5 ml) and tetrahydrofuran (5 ml) were charged into a clean and dry RBF at 25-30°C. Raised the resulting reaction mixture temperature to 60-65°C and stirred for 7 hrs at same temperature. Filtered the precipitated solid and then dried to get the title compound (Yield: 670 mg).
The obtained Form-Ill is characterized by PXRD pattern having characteristic peaks at about 4.1, 15.5, 18.6, 19.8, 23.0 ±0.2°of 20 as illustrated in figure-6.
Example-19: Preparation of Empagliflozin-L-proline crystalline complex (Form-IV)
Empagliflozin (500 mg) and L-proline (100 mg), ethanol (10 ml) and toluene (10 ml) were charged into a clean and dry RBF at 25-30°C. Raised the resulting reaction mixture temperature to 60°C and stirred for 8 hrs at same temperature. Filtered the obtained precipitated solid and dried to get the title compound (Yield: 420 mg).
The obtained of Empagliflozin-L-proline crystalline complex (Form-IV) is characterized by PXRD having peaks at about 4.2, 12.8, 15.6, 18.2, 18.7 ± 0.2° of 20 as illustrated in figure-7.

Claims:
1. A process for the preparation of D-glucitol, l,5-anhydro-l-C-[4-chloro-3-[[4-[[(3,S)-
tetrahydro-3-furanyl]oxy]phenyl] methyl] phenyl]-, (IS) (Empagliflozin) of formula-1,
comprising the steps of:
5 a) Reducing the compound of general formula-2 using a suitable reducing agent in
presence of metal catalyst in a solvent to provide the compound of general formula-3;
wherein, the metal catalyst is TiCU; R is an alkyl group having C1-C5 carbon atoms; X is a halogen atom selected from bromo or iodo. b) reacting the compound of general formula-3 with the compound of formula-4 in presence of suitable organolithium reagent followed by treating with suitable acid in suitable solvent to provide the compound of general formula-5;
wherein, Ri is hydrogen or alkyl group having C1-C5 carbon atoms.
c) optionally, isolating the compound of general formula-5;
d) reducing the product of step-b) or step-c) with a suitable reducing agent in a suitable solvent to provide the compound of general formula-6;

e) optionally, isolating the compound of general formula-6;
f) reacting the product of step-d) or step-e) with a suitable protecting agent in presence of a suitable base in suitable solvent to provide the compound of general formula-7;

wherein, Pg is a protecting group, g) reacting the compound of general formula-7 with a suitable thiol reagent in presence of a suitable Lewis acid catalyst to provide the compound of general formula-8;
h) coupling the compound of general formula-8 with the compound of general formula-9 in presence of a base in a solvent to provide the compound of general formula-10;

wherein, R' is aryl or alkyl sulfonyl group which is substituted with one or more electron withdrawing groups selected from NO2, -NH3+, -N(Ri)3, -CN, -CHO, -COOH, trifluoroalkyl, halogens wherein, Ri is alkyl having C1-C5 carbon atoms, i) deprotecting the compound of general formula-10 to provide compound of formula-1.
2. A process for the preparation of Empagliflozin of formula-1, comprising the steps of:
a) Reducing (5-bromo-2-chlorophenyl)(4-methoxyphenyl)methanone with triethylsilyl hydride in presence of titanium tetrachloride in methylene chloride to provide 4-bromo-l-chloro-2-(4-methoxybenzyl)benzene;
b) reacting 4-bromo-l-chloro-2-(4-methoxybenzyl)benzene with (3R,4S,5R,6R)-3,4,5-tris((trimethylsilyl)oxy)-6-(((trimethylsilyl)oxy)methyl)tetrahydro-2//-pyran-2-one compound of formula (4) in presence of «-butylithium in a solvent followed by

treating with aqueous HC1 and water to provide (2^,37?,4,S',5)S',6i?)-2-(4-chloro-3-(4-
methoxybenzyl)phenyl)-6-(hydroxymethyl)-2-hydroxytetrahydro-2//-pyran-3,4,5-
triol;
c) reducing the product obtained in step-b) with triethylsilylhydride in presence of BF3.etherate to provide (25',3i?,4i?,55',6i?)-2-(4-chloro-3-(4-methoxybenzyl)phenyl)-6-(hydroxymethyl)tetrahydro-2//-pyran-3,4,5-triol;
d) reacting the product obtained in step-c) with aceticanhydride in presence of DMAP in methylene chloride to provide (2i?,3i?,4i?,5,S',6)S)-2-(acetoxymethyl)-6-(4-chloro-3-(4-methoxy benzyl)phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate;
e) reacting the product obtained in step-d) with dodecanethiol in presence of AICI3 to provide the (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-hydroxybenzyl) phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate;
f) reacting the product obtained in step-e) with (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate in presence of K2CO3 in DMF to provide (2i?,3i?,4i?,5,S',6)S)-2-(acetoxymethyl)-6-(4-chloro-3-(4-(((,S)-tetrahydrofuran-3-yl)oxy)benzyl)phenyl)tetra hydro-2//-pyran-3,4,5-trityl triacetate;
g) deprotecting the product obtained in step-f) to provide the compound of formula-1.
3. A process for the preparation of Empagliflozin of formula-1, comprising the steps of:
a) reacting the compound of general formula-7 with a suitable thiol reagent in presence of a suitable Lewis acid catalyst to provide the compound of general formula-8;
wherein, Pg is a protecting group and R is an alkyl group having C1-C5 carbon atoms b) reacting the compound of general formula-8 with the compound of general formula-9 in presence of a base in a solvent to provide the compound of general formula-10;

wherein, R' is aryl or alkyl sulfonyl groups which are substituted with one or more electron withdrawing groups selected from NO2, -NH3+, -N(Ri)3, -CN, -CHO, -COOH, trifluoroalkyl, halogens wherein, Ri is alkyl group having C1-C5 carbon atoms. Preferably, phenyl group substituted with -NO2 in the 2n or 4* position, c) deprotecting the compound of general formula-10 in presence of suitable base in a suitable solvent to provide the Empagliflozin of formula-1.
4. A process for the preparation of Empagliflozin, comprising:
a) Reacting (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-methoxybenzyl phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate with dodecanethiol in presence of AICI3 to provide (2R, 3i?,4i?,5S,6S)-2-(acetoxymethyl)-6-(4-chloro-3-(4-hydroxybenzyl)phenyl)tetrahydro-2//-pyran-3,4,5-triyl triacetate;
b) reacting product obtained in step-a) with (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate in presence of K2CO3 in dimethylformamide to provide (2i?,3i?,4i?,5^,65)-2-(acetoxymethyl)-6-(4-chloro-3-(4-(((5)-tetrahydrofuran-3-yl)oxy)benzyl)phenyl)tetrahydro-2//-pyran-3,4,5-trityl triacetate;
c) deprotecting the product obtained in step-b) to provide the Empagliflozin.
5. A process for the preparation of compound of general formula-8, comprising:
dealkylating the compound of general formula-7 with suitable thiol reagent in presence of
a suitable Lewis acid catalyst to provide the compound of general formula-8.

wherein, Pg is a protecting group and R is an alkyl group having C1-C5 carbon atoms. 6. The compound of general formula-9
wherein, R' is aryl or alkyl sulfonyl group which is substituted with one or more electron withdrawing groups selected from N02, -NH3+, -N(Ri)3, -CN, -CHO, -COOH, trifluoroalkyl, halogens, wherein, Ri is alkyl group having C1-C5 carbon atoms.
7. (i?)-Tetrahydrofuran-3-yl 4-nitrobenzenesulfonate.
8. Solid compound of (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate.
9. A process for the preparation of (i?)-tetrahydrofuran-3-yl 4-nitrobenzenesulfonate of formula-9a, comprising: reacting (i?)-tetrahydrofuran-3-ol with 4-nitrobenzene-l-sulfonyl chloride of formula-lla in presence of DMAP and TEA in methylene chloride.
10. A process for the preparation of (i?)-tetrahydrofuran-3-ol, comprising: reacting (S)-tetrahydrofuran-3-ol with /?-nitrobenzoic acid in presence of triphenylphosphine and diisopropyl azodicarboxylate in a suitable solvent followed by treating the obtained compound with a base in a solvent to provide (i?)-tetrahydrofuran-3-ol.