Synthesis of Benzoxazinones via DIPEA‐Promoted Condensation of Benzoxazoles with α‐Keto Acids

Abstract An efficient and environmental protocol for the synthesis of 3‐aryl‐2H‐benzo[b][1,4]oxazin‐2‐ones under mild benign conditions has been developed. This facile one‐pot approach to 3‐aryl‐2H‐benzo[b][1,4]oxazin‐2‐ones from commercially available benzoxazoles and α ‐keto acids which only promoted by DIPEA. The protocol exhibits a wide range of applicability in terms of benzoxazoles and α‐keto acids. Notably, the 2‐aryl benzothiazoles can be produced under the similar reaction conditions.