Synthesis of a new N-acetyl thiazolidinethione reagent and its application to a highly selective asymmetric acetate aldol reaction.

[reaction: see text] 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.