Synthesis of 4-alkylidene-4H-3,1-benzoxazine derivatives by acid-catalyzed cyclization of 2-isocyanophenyl ketones in the presence of a vinyl ether
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. Georg Thieme Verlag Stuttgart.