Process for the preparation of vitamin D analogues

摘要

A stereospecific method for accomplishing the below reaction: results in the compound of formula 2 having the same stereochemistry at both carbon 1 and carbon 3 as that in the compound of formula 1. Thus, if carbon 3 is in the R-configuration in the compound of formula 1, then carbon 3 will be in the R-configuration in the compound of resulting formula 2. In the above process, R<1> is C1-C6 alkyl that can be straight-chain or branched. The process functions using a fluorinated alcohol having a pKa less than about 9, in the presence of a palladium catalyst. The compounds of formula 1, as well as novel intermediates in this process, are useful in manufacturing vitamin D analogs.