Synthesis of Benzoxazines, Quinazolines and 4H-Benzo[e][1,3]thiazine by ANRORC Rearrangements of 1,2,4-Oxadiazoles

Abstract

1,2,4-Oxadiazoles undergo ANRORC (addition of nucleophile, ring-opening and ring-closure) rearrangements upon reaction with excess of n-butyllithium to give benzoxazines, benzothiazines, and quinazolines in good yields under mild conditions.