New chiral acetal auxiliaries based on fenchone and camphor.

Abstract

Two inexpensive non-racemic, chiral lactols based on camphor and fenchone were developed in an efficient fashion as valuable additions to the methodology available to the chemist who desires to use chiral acetal auxiliaries in a synthetic scheme. THe non-racemic, chiral acetals act as effective protecting groups for alcohols, which after the development of a new carbon, can be readily removed and recycled. The value of this synthetic approach was illustrated by the alkyation of camphor-based and fenchone-based lactols with propargyl bromide to a single isomer that was subsequently converted to an allene and used for generating chiral anion intermediates.