FIELD OF INVENTION:
This improved invention relates to the process for stereoselective synthesis of 4-AA.

R1: H, R2: TBDMS, R3: CH3CO.
The present invention relates to the improved process for stereoselective synthesis of (3R,4R)-4-Acetoxy-3-[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4-AA).
The present invention relates to process for the preparation of recyclable heterogeneous Ru (0) apatite complex Nano 4% Ru(0)FAP (Ru(O)FAP) and application for acetoxylation of the beta-lactam. Here the Ru metal content in the catalyst is reduced by 10 times, hence the method is economical.
The present innovation relates to the improved process for preparation of sultamamide, here replacement of hazardous and expensive reagents NaH or diisopropylethylamine in tetrahydrofuran (THF) with an easily available and cheaper triethylamine (TEA) in methylene dichloride (MDC).
The present innovation relates to the process for the protection of hydroxy group with tert-butyldimethylsilyl chloride (TBDMSCI) in MDC (instead of N,N'-Dimethylformamide (DMF)) is shifted from step 5 to step 7 in scheme I to reduce the quantity of the very expensive TBDMSCI to impart substantial price reduction.
This present innovation also relates to process for cyclization with 3 M MeMgCI solution in THF to form beta-lactam without TBDMS protection in scheme II.
BACKGROUND OF THE INVENTION:
Review of reference is made to Tetrahedron 1996, 52, 331-375, Preparation of two pivotal intermediates for the synthesis of carbapenem antibiotics.

Reference is made to Tetrahedron Lett. 1996, 37, 5565-5568, disclosing facile synthesis of the key intermediates for penems, carbapenems.
Reference is made to Bull. Korean Chem. Soc. 1997, 18, 475-478 disclosing stereo controlled synthesis of 4-acetoxy-2-azetidinone via double azetidinone ring formation.
Reference is made to Tetrahedron Lett. 1998, 39, 7779-7782 disclosing a practical synthesis of a key intermediate for the production of beta-lactam antibiotics.
Reference is made to Chirality 1998, 10, 91-94 disclosing a short, stereoselective synthesis of 4-AA.
Reference is made to J. Am. Chem. Soc. 1997, 119, 4317-4318 wherein the process for preparing Methyl (3R)-hydroxy-2-methylenebutanoate, an important intermediate via asymmetric Baylis-Hillman reaction is disclosed.
Reference is made to Tetrahedron Asymmetry, 1991, 2:12, 1359-1370 and J. Org. Chem. 1995, 60, 2271-2273. Wherein the preparation for Bornane-10,2-Sultam derivatives is disclosed using hazardous and expensive reagents NaH or diisopropylethylamine in THF.
Reference is made to Synthetic Communications, 2008, 38, 456 - 464. A novel synthesis of (3R,4R)-4-Acetoxy-3-[1'(R)- (tert-butyldimethylsilyloxy)ethyl] azetidin-2-one, a key intermediate for Penem and Carbapenem synthesis. A serious disadvantage in this synthesis for target compound is high cost of 40% RuCI3 hydrate, and it is non-recyclable. And also expensive TBDMS protection in DMF, at early stage of the synthesis with this they used large quantity, alternatively this is cost effective.
European patents 0369691A2 and 0371875A2 disclose process for acetoxylation carried out using various Ruthenium complexes RuX3 (RuCI3, RuBr3, Rul3) and their hydrates, Ru-acetate, Ru-Phosphene complexes, Ru-Amine complexes, Ru-Nitrosyl complexes, Ru-Olefin complexes, Ru-carbonyl complexes and Ru-Oxo

complexes, Ruthenium supported carbon, graphite, alumina, silica-alumina, zeolite, iron oxide, zirconium oxide and diatomaceous earth for synthesis of 4-AA. Although various catalysts are used for synthesis of 4-AA, it was only 40% RuCI3 hydrate which has yielded optimum results for acetoxylation of the beta-lactam.
OBJECTS OF INVENTION:
1) The main object of the present invention is to provide the development of a cost effective, and scalable method for preparing the stereoselective synthesis of (3R,4R)-4-Acetoxy-3-[1 '(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4-AA).
2) Another object of the present invention relates to process for the preparation of recyclable heterogeneous Ru apatite complex (Ru(O)FAP) and application for acetoxylation of the beta-lactam. Here the Ru metal content in the catalyst is reduced by 10 times, hence the method is economical.
3) Another object of the present innovation also relates to the improved process for preparation of sultamamide, here replacement of hazardous and expensive reagents NaH or diisopropylethylamine in THF with an easily available and cheaper TEA in MDC.
4) Another object of the present innovation relates to the process for the protection of hydroxy group with TBDMSCI in MDC (instead of DMF) is shifted from step 5 to step 7 in scheme I to reduce the quantity of the very expensive TBDMSCI to impart substantial price reduction.
5) Yet another object of the innovation also relates to cyclization with 3 M MeMgCI solution in THF to form beta-lactam without TBDMS protection in scheme II.
DETAILED DESCRIPTION OF THE INVENTION:
The novelty of the invention lies in the improved process for 4-AA.
(i) N-Acryloyl (2R)-bomane-10,2-sultam (2) is prepared by using (-)-D-2,10-
camphorsultam (1) as a recycling chiral auxiliary.

(ii) (-)-D-2,10-camphorsultam (1) was reacted with acryloyl chloride at -5 oC in MDC in the presence of TEA and CuCI to afford the sultamamide (2) in 80% yield.
(iii) Subsequent Baylis-Hilman reaction of sultamamide (2) with acetaldehyde and 1,4-diazabicyclo [2.2.2] octane (DABCO) in MDC for 48 h yielded the 1,3- dioxane-4-one derivative (3), in this step, (-)-D-2,10-camphorsultam (1) was recovered in 70% yield for recycling as per the reported procedure.
(vi) Esterification of derivative (3) directly was carried out without purification, with a catalytic amount of BF3 etherate in refluxing methanol to get compound (4) as per the reported procedure.
(v) Compound (4) was then subjected to diastereoselective Michael addition with benzylamine to get compound (5), with 90% yield.
(vi) Hydrogenolysis of Compound (5) with 20% Pd(OH)2 on carbon in methanol at room temperature yielded amino compound (6) in 98%.
(vii) Silylation of compound (6) with TBDMSCI and imidazole in MDC resulted in silylated ester (7) in 98% yield.
(viii) The work was further developed by silylating the amine (7) with hexamethyldisilazane (HMDS) using a catalytic amount of trimethylsilyl chloride (TMSCI), then reacting with 3 M MeMgCI in THF to afford beta-lactam (8) in 60% yield.
(ix) Beta-lactam was converted to the target molecule (9) by acetoxylation with innovated heterogeneous Ru(0)FAP complex with 70% yield, which was characterized by 1H NMR, Mass, Specific optical rotation and Chiral HPLC.
PREPARATION OF NANO 4% Ru(0)FAP [Ru(0)FAP]:
Heating 1,2-propanediol solution (1000 ml) of RuCI3.xH20 (1.0 g, 3.82 mmole) and NaOAc.3H20 (1.0 g, 7.35 mmole) at 150 oC produced a yellowish brown colour solution. After cooling down to room temperature, the solution was added with

Calcium Fluorapatite (Ca 10(PO4)6F2) (FAP) (4.7 g, 4.66 mmole) and water (500 ml) followed by stirring the mixture for 24 h. The solid was separated by centrifugation and the collected solid was washed with water. Drying the sample at 110 oC for 12 h, afforded 5.0 g of Ru(0)FAP as a dark grey powder.
SYNTHETIC SCHEME I:

SCIENTIFIC EXPLANATION:
In the present invention, novel supported ruthenium is prepared for the first time by the ion exchange method using hydroxy apatite as supported species. The Ru (0) present on the support are responsible for the acetoxylation activity of the reaction. The activity of the supported ruthenium is similar or higher than the homogeneous counterparts. Without wishing to be bound by any theory, it is believed that the higher activity is ascribed to the support effect. The large ionization potential of Ru (0) support surface induces polarization of C-»0 bond and facilitates acetoxylation. The present innovation relates to the improved process which replaces hazardous and expensive reagents NaH or diisopropylethylamine in THF with an easily available and cheaper TEA in MDC.

The present innovation relates to the process for the protection of hydroxy group with TBDMSCI in MDC (instead of DMF) by shifting to step 7 from step 5 in scheme I to reduce the quantity of the very expensive TBDMSCI to impart substantial price reduction.
This present innovation also relates to cyclization with 3 M MeMgCI solution in THF to form beta-lactam without TBDMS protection (Scheme II).
Step (i) of scheme 1
Selecting (-)-D-2,10-camphorsultam (1) as a recycling chiral auxiliary for
stereoselective synthesis of N-Acryloyl (2R)-bomane-10,2-sultam (2).
Step (ii) of scheme 1 N-Acryloyl (2R)-bomane-10,2-sultam:
To the mixture of (-)-D-2,10-camphorsultam (1) (100 g, 0.511 mole) in MDC (1000 ml), CuCI (10.1 g, 0.1 mole) was added, followed by TEA (103.5 g, 1.02 mole) at RT during 15 min. Mixture was cooled to -5 oC. Then solution of MDC (100 ml) and acryloyl chloride (55.5 g, 0.612 mole) was added drop wise to it at -5 oC over 1 h. The reaction mixture was stirred at the same temperature for 2 h. Reaction was monitored by thin-layer chromatography (TLC), isolated the product with an appropriate workup to give N-Acryloyl (2R)-bornane-10,2-sultam (2). (110 g, 80%). [a]D20o, -95o (C 1.05, CH2CI2), MP: 189-192oC. 1H NMR (300 MHz, CDCI3) d 0.98 (s, 3H), 1.18 (s, 3H), 1.33-1.45 (m, 2H), 1.8- 1.98 (m, 3H), 2.0-2.2 (m, 2H), 3.5 (ABq, 2H, J = 13.8 Hz), 3.9 (dd, 1H, J1 = 5.34 Hz, J2 = 5.31 Hz), 5.8 (d, 1H, J = 10.32 Hz), 6.5 (d, 1H, J = 16.62 Hz), 6.85 (dd, 1H, J1 = 10.32 Hz, J2 = 10.32 Hz). MS m/z(M+1)270.1.
Step (iii) of scheme 1
(2R,6R)-2,6-Dimethyl-5-methylene-1,3-dioxan-4-one:
To the mixture of Sultamamide (2) (100.0 g, 0.0.371 mole) and DABCO (20.8 g, 0.18
mole) in MDC (500 ml), CH3CHO (196 g, 4.45 mole) was added slowly at 0-5 oC
and stirred at the same temperature for 48 h. TLC monitored the reaction progress.
Isolated the product with an appropriate workup with isopropyl ether to give recovery
of (-)-D-2,10-camphorsultam (1) (55.9 g, 70%) and (2R,6R)-2,6-Dimethyl-5-

methylene-1,3-dioxan-4-one (3) (31.6 g, yellowish oil 60%), which was used in the next step without purification. A small quantity of the sample was further purified by silicagel column chromatography and characterized. 1H NMR (300 MHz, CDCI3) d 1.48 (d, 3H, J = 6.3 Hz), 1.5 (d, 3H, J = 5.4 Hz), 4.6 (M, 1H), 5.5 (q, 1H), 5.6 (d, 1H, J = 2.1 Hz), 6.5 (d, 1H, J = 2.4 Hz). MS m/z (M+1) 143.0.
Step (iv) of scheme 1
Methyl (3R)-hydroxy-2-methylenebutanoate:
To the mixture of crude compound (3) (100 g, 0.704 mole) in methanol (500 ml), BF3 etherate (33 g, 0.232 mole) was added drop wise at 0 oC in 30 min and stirred for 1 h at the same temperature for complete ring opening. TLC monitored the reaction progress, and then refluxed for 24 h for esterification. Isolated the product with an appropriate workup to give the oily mass and was distilled under high vacuum (vapor temp: 40-45oC, oil bath temp: 70-1 OOoC) to afford Methyl (3R)-hydroxy-2-methylenebutanoate (64.1 g, 70% based on dioxane (3), as light yellow oil. Optical purity: 98 % ee, [ct]D 20o +10.2 (C 0.8, CHCI3), 1H NMR (300 MHz, CDCI3) d 1.4 (d, 3H, J = 6.45 Hz), 2.7 (d, 1H, J = 5.34 Hz), 3.8 (s, 3H), 4.62 (q, 1H), 5.83 (s, 1H), 6.2 (s, 1H). MS m/z (M+1) 131.1.
Step (v) of scheme 1
Methyl (2S,3R)-2-[(benzylamino)methyl]-3-hydroxy butanoate:
To the mixture of compound (4) (100 g, 0.769 mole) and benzylamine (90 g, 0.83
mole) in methanol (500 ml) was stirred for 48 h at RT. TLC monitored the reaction
progress.
Isolated the product with an appropriate workup to give Methyl (2S,3R)-2-[(benzylamino)methyl]-3-hydroxy butanoate(5) (164 g, 90%). 1H NMR (300 MHz, CDCI3) 1.15 (d, 3H, J = 6.15 Hz), 2.6 (m, 1H), 2.9 (m, 2H), 3.7 (s, 3H), 3.8 (s, 2H), 4.1 (m, 1H), 7.3 (s, 5H). MS m/z (M+1) 238.2.
Step (vi) of scheme 1
Methyl (2S,3R)-2-aminomethyl-3-hydroxybutanoate:
To the mixture of compound (5) (100 g, 0.421 mole) in methanol (500 ml), 20%
Pd(OH)2 on carbon (10 g) was charged and stirred under hydrogen pressure (8.5

kg/cm2) for 8 h, TLC monitored the reaction progress. The catalyst was filtered, and the filtrate was concentrated to give Methyl (2S,3R)-2-aminomethyl-3-hydroxybutanoate (6) (60.8 g, 98%) as a viscous oil. 1H NMR (300 MHz, CDCI3) 1.2 (d, 3H, J = 6.18 Hz), 2.5 (m, 1H), 3.0 (m, 2H), 3.7 (s, 3H), 4.15 (m, 1H). MS m/z (M+1) 148.2.
Step (vii) of scheme 1
Methyl (2S,3R)-2-aminomethyl-3-(tert-butyldimethylsilyloxy)butanoate:
To the mixture of compound (6) (100 g, 0.679 mole) and imidazole (92.45 g, 1.358
mole) in MDC (500 ml), TBDMSCI (112.65 g, 0.747 mole) in 100 ml MDC was added
slowly at 10-15 oC and stirred for 8-10 h at RT, reaction was monitored by TLC and
isolated the product with an appropriate workup to afford Methyl (2S,3R)-2-
aminomethyl-3-(tert-butyldimethylsilyloxy)butanoate (7) (173.9 g, 98%) as yellow oil.
1H NMR (300 MHz, CDCI3) d 0.08 (s, 6H), 0.9 (s, 9H), 1.25 (d, 3H, J = 6.24 Hz), 2.5
(m, 1H), 3.0 (m, 2H), 3.7 (s, 3H), 4.15 (m, 1H). MS m/z (M+1) 262.5.
Step (viii) of scheme 1
(1 R,3S)-3-[1 '-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one: Under nitrogen atmosphere the compound (7) (100 g, 0.382 mole) was dissolved in MDC (500 ml) and was added to HMDS (74 g, 0.459 mole) followed by small amount of TMSCI (5 g, 0.046 mole). The mixture was refluxed for 4-5 h. MDC was distilled, and the oily silylated mass was dissolved in THF (300 ml). The solution was added to the 3M MeMgCI in THF (550 ml) at RT in 1 h, stirred at the same temperature for 1 h, and reaction was monitored by TLC and isolated the product with an appropriate workup and purified to afford (1R,3S)-3-[1'-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (8) (52 g, 60% yield) as a white solid. MP: 67.5oC. [a]D20o -64.9 (C 1.0, CHCI3), 1H NMR (300 MHz, CDCI3) d 0.075 (s, 3H), 0.08 (s, 3H), 0.87 (s, 9H), 1.2 (d, 3H, J = 6.24 Hz), 3.2 (m, 1H), 3.26-3.30 (t, 1H, J1 = 5.1 Hz, J2 = 5.1 Hz), 3.33 (m, 1H), 4.2 (m, 1H), 5.55 (brs, 1H, -NH). MS m/z (M+1) 230.1.
SYNTHETIC SCHEME-II:


This is another innovative route for the synthesis of beta-lactam.
Step (viii) of scheme I is step (vii) in scheme II and step (vii) of scheme I is step (viii) in scheme II. The yield of cyclization step (vii) of scheme II (6 to 7A) is low (40%) when compared from the above scheme I, but 98% yield for the step (viii) (7A to 8) in scheme II.
Step (vii) of scheme II
(1R,3S)-(1'-hydroxy ethyl) azetidin-2-one:
Under nitrogen atmosphere the compound (6) (10 g, 0.068 mole) was dissolved in
MDC (50 ml) and was added to HMDS (13.2 g, 0.081 mole) followed by TMSCI (1 g).
The mixture was refluxed for 4 h. MDC was distilled, and the oily silylated mass was
dissolved in THF (50 ml). The solution was added to the 3M MeMgCI in THF (50 ml)
at RT in 30 min, stirred at the same temperature for 1 h, and monitored by TLC and
isolated the product with an appropriate workup and purified to afford (1R,3S)-(1'-
hydroxy ethyl) azetidin-2-one (7A) (3.12g, 40%).
1H NMR (300 MHz, CDCI3) 1.2 (d, 3H, J = 6.24 Hz), 3.2 (m, 1H), 3.26 (t, 1H, J1 =
5.1 Hz, J2 = 5.1 Hz), 3.33 (m, 1H), 4.2 (m, 1H), 5.55 (brs, 1H, -NH). MS m/z (M+1)
116.1.
Step (viii) of scheme II
(1R,3S)-3-[1'-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one:
To the mixture of compound (7A) (3 g, 0.026 mole) and imidazole (3.54g, 0.052mole)
in MDC (20 ml), TBDMSCI (4.3 g, 0.0286mole) in 10 ml MDC was added drop wise
at 10-15 oC in 30 min and additionally stirred for 4-8 h at RT, TLC monitored the
reaction progress. Isolated and purified to afford (1R,3S)-3-[1'-(tert-


100 g (0.436 mole) of compound (8) was dissolved in 600 ml MDC under nitrogen atmosphere further added 100 g sodium acetate (1.21 mole) at RT. To this 10 g of Ru(0)FAP (0.1 w/w) was added at RT. Reaction mixture was cooled to -5 oC, to this 600 ml acetic acid solution containing 40% peraceticacid was added drop wise in 6-7 hours at -5 oC and maintained for 2 hrs at -5 oC. TLC monitored the reaction progress. Isolated the compound with appropriate workup and purified to obtain 87.5 g (70%) of (3R,4R)-4-Acetoxy-3-[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one(9). Ru(0)FAP catalyst recovered and recyclable. [a]D20o +52.3o (C 0.5 Toluene), 1H NMR (300 MHz, CDCI3) d 0.075 (s, 3H), 0.08 (s, 3H), 0.85 (s, 9H), 1.25 (d, 3H, J = 6.33 Hz), 2.1 (s, 3H) 3.2 (dd, 1H, J1 = 3.3 Hz, J2 = 1.2 Hz), 4.2 (m, 1H),5.8 (d, 1H, J =1.27 Hz),6.5 (br s, 1H, -NH). MS m/z (M+ Na) 310.1.], MP: 107-107.6oC. Optical purity: 98.05% ee.

WE CLAIM:
1. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA).
OR2NR100R3
wherein R1is Hydrogen, R2 is TBDMS, R3 is CH3CO-, wherein the said
process comprising of following steps and characterized in the sequence of the
steps;
(i) selecting (-)-D-2,10-camphorsultam (1) as a recycling chiral auxiliary,
(ii) reacting (-)-D-2,10-camphorsultam (1) with acryloyl chloride at -5 oC in
MDC in the presence of TEA and CuCI to form sultamamide (2),
(iii) the sultamamide (2) reacting with acetaldehyde and 1,4-diazabicyclo
[2.2.2] octane (DABCO) in MDC for 48 h to yield 1,3- dioxane-4-one derivative
(3),
(iv) 1,3- dioxane-4-one derivative (3) esterifying with catalytic amount of BF3
etherate in refluxing methanol to get a compound (4),
(v) the compound (4) on treating with benzylamine to get a compound (5),
(vi) the compound (5) on hydrogenolysis with 20% Pd(OH)2 on carbon in
methanol at room temperature to yield amino compound (6);
(vii) silylating compound (6) with TBDMSCI and imidazole in MDC to yield
silylated ester (7),
(viii) cyclisation of compound (7) with hexamethyldisilazane (HMDS) using a
catalytic amount of trimethylsilyl chloride (TMSCI), and then reacting with 3 M
MeMgCI in THF to afford beta-lactam (8),
(ix) acetoxylation of compound (8) with heterogeneous Ru(0)FAP complex to
form compound (9) (4-AA).
2. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA),


wherein R1is Hydrogen, R2 is TBDMS, R3 is CH3CO-, wherein the said
process comprising of following steps and characterized in the sequence of
the steps;
(i) selecting (-)-D-2,10-camphorsultam (1) as a recycling chiral auxiliary,
(ii) reacting (-)-D-2,10-camphorsultam (1) with acryloyl chloride at -5 oC in
MDC in the presence of TEA and CuCI to form sultamamide (2),
(iii) the sultamamide (2) reacting with acetaldehyde and 1,4-diazabicyclo
[2.2.2] octane (DABCO) in MDC for 48 h to yield 1,3- dioxane-4-one derivative
(3),
(iv) 1,3- dioxane-4-one derivative (3) esterifying with catalytic amount of BF3
etherate in refluxing methanol to get a compound (4),
(v) the compound (4) on treating with benzylamine to get a compound (5),
(vi) the compound (5) on hydrogenolysis with 20% Pd(OH)2 on carbon in
methanol at room temperature to yield amino compound (6),
(vii) cyclisation of compound (6) with hexamethyldisilazane (HMDS) using a
catalytic amount of trimethylsilyl chloride (TMSCI), and then reacting with 3 M
MeMgCI in THF to form compound (7A),
(viii) silylating compound (7A) with TBDMSCI and imidazole in MDC to yield
silylated ester (8),
(ix) acetoxylation of compound (8) with heterogeneous Ru(0)FAP complex to
form compound (9) (4-AA).
3. A process for producing a compound 9 (4-AA), wherein said process comprising the following steps (i) ,(ii),(iii) and (iv):
(i) reacting compound 1 with acryloyl chloride in MDC in the presence of TEA
and CuCI,
(ii) silylation of compound 6 with TBDMSCI in MDC,
(iii) cyclization from compound 7 to compound 8 comprising that reacting with
hexamethyldisilazane (HMDS) and TMSCI, then reacting with MeMgCI,
(vi) acetoxylation of compound 8 with Ru(0)FAP.
4. A process for producing a compound 9 (4-AA), wherein said process comprising he following steps (i) ,(ii'),(iii') and (iv):
(i) reacting compound 1 with acryloyl chloride in MDC in the presence of TEA

and CuCI,
(ii) cyclization from compound 6 to compound 7A comprising that reacting with
hexamethyldisilazane (HMDS) and TMSCI, then reacting with MeMgCI,
(iii) silylation of compound 7A with TBDMSCI in MDC,
(iv) acetoxylation of compound 8 with Ru(0)FAP.
5. A process for preparing heterogeneous Ru(0)FAP complex comprising of ion exchange of hydroxyl apatite with ionic Ruthenium.
6. The ion exchange method as claimed in claim 5 comprising of following steps
a. heating 1,2-propanediol solution of RuCI3.xH20 and NaOAc.3H20 at
150 °C;
b. cooling down to room temperature,
c. adding Calcium Fluorapatite (Ca10(PO4)6F2) (FAP) and water,
d. stirring the mixture for 24 h,
e. separating the solid by centrifugation and washing with water,
f. drying the sample at 110 oC 12 h, afforded Ru(0)FAP as a dark grey
powder.
7. A process of preparing the heterogeneous Ru(0)FAP complex of step (ix) in
claim 1 and 2 comprises of ion exchange method as claimed in claim 5 comprising of
following steps:
a. heating 1,2-propanediol solution of RuCI3.xH20 and NaOAc.3H20 at 150
°C;
b. cooling down to room temperature,
c. Adding Calcium Fluorapatite (Ca10(PO4)6F2) (FAP) and water,
d. stirring the mixture for 24 h,
e. separating the solid by centrifugation and washing with water,
f. drying the sample at 110 oC 12 h, afforded Ru(0)FAP as a dark grey
powder.
8. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in Step (ii) of claim 1 and 2 wherein the yield is 80%.

9. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in step
(iii) of claim 1 and 2 along with derivative (3) recyclable camphorsultam (1) is recovered.
10. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in step
(iii) of claim 1 and 2 wherein the yield of recyclable camphorsultam (1) is 70%.
11. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in step
(iv) of claim 1 and 2 wherein the esterification is without purification step.
12. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in step
(v) of claim 1 and 2 wherein the yield of compound (5) is 90%.
13. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in Step
(vi) of claim 1 and 2 wherein the yield of amino compound (6) is 98%.
14. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in Step (vii) of claiml wherein the yield of compound (7) is 98%.
15. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in Step (vii) of claim2 wherein the yield of compound (7A) is 40%.
16. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in Step (viii) of claim 1 wherein the yield of compound (8) is 60%.

17. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in Step
(viii) of claim 2 wherein the yield of compound (8) is 98%.
18. A process for stereoselective synthesis of a compound (3R,4R)-4-Acetoxy-3-
[1'(R)-(tert-butyldimethylsilyloxy)ethyl] azetidin-2-one (4AA), as claimed in step
(ix) of claim 1 and 2 wherein the yield of compound (9) is 70%.