Preparation of β-lactams from Optically Active Isocyanate and Vinyl Ethers under High Pressure

Abstract

The [2+2] cycloaddition of (S) - (-) - and (R) - (+) -α-methylbenzyl isocyanate to 2, 3-dihydrofuran was accelerated by compression to produce four diastereomers of a β-lactam. The diastereomers were isolated and the absolute configuration of each diastereomer was determined. The ratio of diastereomer was about 51/49 and did not change with pressure, reaction temperature, and kind of solvent. The reaction of (S) - (+) -1- (1-naphthyl) ethyl isocyanate with 2, 3-dihydrofuran and the reaction of (S) - (-) -α-methylbenzyl isocyanate with various vinyl ethers under high pressure gave similar reactivity and diastereoselectivity to the reaction of α-methylbenzyl isocyanate with 2, 3-dihydrofuran.