Catalyst-free reactions of Schiff bases with cyanopropargyl alcohols: synthesis of functionalized 1,3-oxazolidines

Abstract

Schiff bases react with cyanopropargylic alcohols (80°C, 10-12 h) in the absence of catalysts and solvents to afford functionalized 1,3-oxazolidines in up to 82% yield. The reaction proceeds through a cascade of transformations including the formation of a 1,3-dipolar intermediate via the addition of a neutral N -nucleophile to the activated triple bond, the proton transfer from the hydroxyl group to the carbanionic center of the intermediate, and the intramolecular attack of the carbonyl carbon of the Schiff base by the O -centered anion to close 1,3-oxazolidine cycle.