Synthesis of a New N-Acetyl Thiazolidinethione Reagent and Its Application to a Highly Selective Asymmetric Acetate Aldol Reaction

A new N-acetyl thiazolidinethione reagent, which undergoes highly diastereoselective aldol reactions upon enolization with dichlorophenylborane and (−)-sparteine and subsequent treatment with a variety of aldehydes, is described. This reagent is pseudoenantiomeric to an l-tert-leucine-derived reagent recently described by us and is useful because it avoids the prohibitively costly d-tert-leucine.