4‐Substituted‐3‐alkyl‐3,4‐dihydro‐2H‐1,3‐benzoxazin‐2‐ones. IV (2‐4). Keto‐Enol tautomerism of β‐keto ester derivatives. Reaction of β‐dicarbonyl compounds with diamines

Abstract

AbstractA series of α‐[3‐alkyl‐3,4‐dihydro‐2‐oxo‐2H‐1,3‐benzoxazin‐4‐yl]‐β‐keto ester derivatives 1 (Table I) were synthesized by the condensation of 3‐alkyl‐3,4‐dihydro‐4‐hydroxy‐2H‐1,3‐benzoxazine‐2‐ones 3 (2) with β‐keto esters 4 in the presence of traces of mineral acids under azeotropic conditions. Condensation of 1 with hydrazines 5 gave pyrazolone derivatives 2 (Table II). Condensation of β‐diketone derivatives 6 with hydrazines 5 and with 1,2‐benzenediamine (8) resulted in the formation of pyrazoles (7a‐c) and diazepine derivatives 12 (Table III) and 13, respectively.