The Unexpected Reorganizations of a β-Lactone Aldolate to 1,3-Dioxan-4-ones in the Reaction of 4-(1-Methylethyl)-3-[(phenylthio)methyl]-1-oxetan-2-one Lithium Enolate with Acetaldehyde

The lithium enolate 4-(1-methylethyl)-3-[(phenylthio)methyl]-1-oxetan-2-one (1), generated from the conjugate addition of lithium thiophenolate to α-methylene-β-lactone 2, reacts with acetaldehyde to give the 1,3-dioxan-4-ones 3 and 4 as unexpected aldol products. These products result from unusual aldol reorganization processes, which entail a complex cascade of aldol additions, retroaldol cleavages and translactonizations. The configurations of the products have been determined by NOE experiments.