ChemInform Abstract: Synthesis of 2-Vinylcyclopentanols by SmI2/Pd(0)-Promoted Carbohydrate Ring-Contraction.

The treatment of methyl 5-vinylpyranosides with SmI2/cat. Pd(0) results in the formation of 2-vinylcyclopentanols. This process represents a new direct transformation of a carbohydrate structure into a functionalized carbocycle. The salient feature of this reaction is the preferred trans-relationship observed between the newly created stereocenters which is opposite to that found with alternative methodology. Moderate diastereoselectivities combined with high chemical yields provide preparatively useful yields of the major carbocyclic trans-diastereomer.