Silicon-directed diene synthesis

Abstract

A synthesis of 2-substituted-1,3-dienes is reported which uses silicon as a control element: Eight aldehydes were converted into α-silyl ketones by treatment with trimethylsilylmethylmagnesium chloride and rapid Collins oxidation. Addition of vinylmagnesium bromide to the resulting α-silyl ketones, followed by Peterson elimination, gave a series of dienes. The route was used to make (4S)-3-methylene-t-[(phenylmethoxy)methoxy]pent-1-ene from (–)-ethyl lactate; low asymmetric induction was observed in the Diels–Alder reactions of this diene with diethyl fumarate and N-phenylmaleimide.