A FACIAL SYNTHESIS OF THE NEUTRAL [1,2,4]TRIAZOLO- [3,2-d][1,5]BENZOXAZEPINES AND THEIR CHALCOGEN-ANALOGUES

ABSTRACT

An expedient synthesis of neutral [1,2,4]triazolo[3,2-d][1,5]-benzoxazepines 6a–e and their chalcogen analogues 6f–i was accomplished via cycloaddition of the heterocumulene cations (3a,b), generated sequentially by action of chroman-4-one as well as thiochroman-4-one ethoxy carbonylhydrazones (1a,b) with t-BuOCl and SbCl₅, to the triple bond of nitriles and concurring ring enlargement and hydrolytic removal of the N(1)-ethoxycarbonyl group. The oily final products were characterized as their picrates.

ACKNOWLEDGMENT

Financial support of this work by the National Natural Science Foundation of China through grant A29872007 and Foundation for University Key Teacher by the Ministry of Education to Q. W. is gratefully acknowledged.