(1S,2S,3R,5R)-2-[(3S)-2-halo-3-hydroxy-1-alken(ynyl)]-3-trialkyl silyloxy-7,7-(2,2-dimethyl-trimethylenedioxy)bicyclo[3.3.0]octane compounds and processes for their preparation

Abstract

The invention concerns a process for preparing (1S,2S,3R,5R)-2-[(3S)-2-halo-3-hydroxy-1-alken(ynyl)]-3-trialkylsilyloxy-7 ,7-(2,2-dimethyltrimethylenedioxy)-bicyclo[3.3.0]octane compounds of general Formula I ##STR1## wherein X is chlorine or bromine, R.sub.1 can mean straight-chain or branched alkyl of up to 6 carbon atoms, straight-chain or branched alkenyl of up to 6 carbon atoms, straight-chain or branched alkynyl of up to 6 carbon atoms, R.sub.2, R.sub.3, R.sub.4 can be in each case identical or different and can mean C.sub.1 -C.sub.4 -alkyl and phenyl optionally substituted by C.sub.1 -C.sub.4 -alkyl groups, wherein the 13,14-double bond has the trans configuration with respect to the C chain, by stereoselective reduction of an .alpha.-halo-enone of general Formula II ##STR2## wherein X, R.sub.1, R.sub.2, R.sub.3, R.sub.4 have the meanings given above, with a reagent produced from diisobutyl aluminum hydride and 2,6-di-tert-butyl-4-methylphenol.

Dependencies are inferred from the claim text.