Patent ID: 8404841

Claim:
A process for the preparation of a compound of Formula-4, wherein denotes a single or a double bond and R is represented by Formula-a, wherein: P 1 and P 2 are alcohol protecting groups or P 1 and P 2 , taken together, form a 1,3-diol protecting group, R′ is hydrogen and R″ is n-butyl, the process comprising: reacting a compound of Formula-2, wherein R is defined as above and is linked to the sulphur atom with a methylene group (—CH 2 —) and R 1 is wherein: R 2 is alkyl, aryl, arylalkyl or cycloalkyl, R 3 is H, alkyl, aryl, arylalkyl, CF 3 , halo or NO 2 , R 4 is H, alkyl, alkoxy, haloalkyl, monohaloalkyloxy, or dihaloalkyloxy, and X is O, N—H, N-alkyl or S; or reacting a compound of Formula-8 wherein R is defined as above and is linked to the phosphorus atom with a methylene group (—CH 2 —); or reacting a compound of Formula-9 wherein R is defined as above and is linked to the phosphorus atom with a methylene group (—CH 2 —), with a compound of Formula-3, wherein: P 1 , P 2 , R′ and R″ are defined as above, in the presence of a base in a solvent, followed by isolating the compound of Formula-4 using hydrocarbon solvent to provide the compound of Formula-4.