Synthesis of 4-Alkylidene-4H-3,1-benzoxazine Derivatives by Acid-Catalyzed Cyclization of 2-Isocyanophenyl Ketones in the Presence of a Vinyl Ether

Abstract

2-(1-Alkoxyalkyl)-4-alkylidene-4H-3,1-benzoxazines are conveniently prepared by the reaction of 1-(2-isocyanophenyl)ethanones or 1-(2-isocyanophenyl)propan-1-ones with a vinyl ether, such as 2-methoxypropene or ethyl vinyl ether, in the presence of a catalytic amount of (±)-camphor-10-sulfonic acid.

Key words

4H-3,1-benzoxazines - acid-catalyzed reaction - fused-ring system - isocyanides - vinyl ethers

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