abstract |
The present invention relates to a process for the preparation of a compound of formula (I) comprising the steps of a) reacting a compound of formula (II) with a silylating or an acylating agent to produce compound of formula (III), wherein P 1 is a protecting group selected from R 2- Si-R 3 R 4 or R 1 CO-, R 1 is a group selected from C 1-6 alkyl or C 3-6 cycloalkyl, each group being optionally substituted by one or more substituents independently selected from fluoro or C 1-4 alkyl; R 2 , R 3 and R 4 are each independently a group selected from C 1-6 alkyl or phenyl, each group being optionally substituted by one or more substituents independently selected from fluoro or C 1-4 alkyl; b) halogenation or sulfinylation of the compound of formula (III) to produce a compound of formula (IV); wherein X is halo, or -O-SO-R 5 , and R 5 is a group selected from C 6-10 aryl or heteroaryl, each group being optionally substituted by one or more substituents independently selected from chloro or C 1-4 alkyl; c) dehalogenation or desulfinylation of the compound of formula (IV) to produce compound of formula (V); and d) reacting the compound of formula (V) with a reducing agent to produce compound of formula (I). |