Tetrahedron letters

High pressure promoted (2+ 2) cycloadditions of ketene acetals with carbonyl compounds

RWM Aben, HW Scheeren

Index: Aben, Rene W. M.; Scheeren, Hans W. Tetrahedron Letters, 1983 , vol. 24, # 42 p. 4613 - 4616

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Citation Number: 12

Abstract

Abstract Cycloadditions of ketene acetals (R 1 R 2 C= C (OR) 2) with carbonyl compounds (R 3 COR 4) are strongly promoted by increase or pressure. At 12 kbar oxetanes are even obtained from very polar ketene acetals (R 1, R 2= H, H or H, Cl) and-in the presence of a Lewis acid-with unactivated ketones (R 3 and R 4= alkyl). The reaction proceeds via a cisoid dipolar transition state; when relevant mainly trans-substituted oxetanes are formed.