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 P1 is a protecting group selected from R2Si—R3R4 or R1CO—, R1 is a group selected from C1-6alkyl or C3-6cycloalkyl, each group being optionally substituted by one or more substituents independently selected from fluoro or C1-4alkyl； R2, R3 and R4 are each independently a group selected from C1-6alkyl or phenyl, each group being optionally substituted by one or more substituents independently selected from fluoro or C1-4alkyl； b) halogenation or sulfinylation of the compound of formula (III) to produce a compound of formula (IV)； wherein X is halo, or —O—SO—R5, and R5 is a group selected from C6-10aryl or heteroaryl, each group being optionally substituted by one or more substituents independently selected from chloro or C1-4alkyl； 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).
