Highly stereocontrolled synthesis of substituted propiolactones and butyrolactones from achiral lithium enolates and homochiral aldehydes

Article abstract of DOI:10.1016/0040-4039(95)02139-6

Lithium enolates derived from achiral thiol esters react in a highly stereoselective fashion with homochiral aldehydes to yield the corresponding 2-oxetanones. The stereochemical outcome of the reaction corresponds to a non-chelation control, except when O-silylated mandelaldehyde is used. The propiolactones thus formed are efficiently transformed into δ-lactones via Lewis acid promoted dyotropic rearrangements.