A New Convenient Method for the Synthesis of 2H‐1,4‐Benzoxazine Derivatives from Nitroketones via Intramolecular Reductive Cyclization.

Abstract

Dedicated to Professor Herbert C. Brown on the occasion of his 90 th birthday.Potentially bioactive 2H-1,4-benzoxazine derivatives could be conveniently prepared in one step from the corresponding nitroketones using 10% palladium on carbon with triethylamine in the presence of hydrogen (Pd/C-TEA-H 2 ) system. Several other tertiary amines such as nicotine, pyridine, and quinoline also could be used, but TEA gave the best results.

Synthesis and Crystal Structure ofN-Dichloroacetyl-3,4-dihydro-3-methyl-6-chloro-2H-1,4-benzoxazine

“…Due to the importance of 1,4-benzoxazine and its derivatives, several synthetic methods have been reported over the past few decades. Most of the reported methods were about the synthesis of specific benzoxazines by O-alkylation, cyclization, and reduction with catalyst to give the target compounds [5,6]. But most of these methods employ harsh reaction conditions, expensive catalysts, or poor yields.…”