The First In(OTf)3 -Catalyzed Conversion of Kinetically Formed Homoallylic Alcohols into the Thermodynamically Preferred Regioisomers: Application to the Synthesis of 22α-Sterols.

ABSTRACT

A retro-ene reaction that generates the parent aldehyde and a sigmatropic rearrangement are involved in the In(OTf)3 -catalyzed conversion of homoallylic alcohols 1 into the thermodynamically favored regioisomers 2. This method can be used for the stereocontrolled synthesis of linear homoallylic 22α-sterols from their readily accessible branched 22ß isomers.