REGIO-SELECTIVE AND STEREOSELECTIVE NUCLEOPHILIC SUBSTITUTIONS OF CHIRAL ALLYLIC ALCOHOL RHENIUM COMPLEXES

The presence of a small amount of a Lewis acid, the nucleophilic subst itution by alcohols, thiols, allyltrimethylsilane, or triphenylphospha ne of the hydroxy group in allylic alcohols complexed to a chiral rhen ium salt affords the corresponding ethers, thioethers, 1,5-dienes, and phosphonium salts in high yield. Similarly, complexed allyl halides a re prepared on treatment with thionyl chloride or phosphorus tribromid e. The efficiency of the reaction strongly depends on the Leu is acid and the leaving group. The high regioselectivity of this reaction was unambiguously determined by means of a deuterated ligand or with subst ituted allylic alcohols. The reaction of the separate diastereoisomeri c rhenium complexes derived from 3-buten-2-ol established that this su bstitution is stereospecific with overall retention of configuration.