Synthesis of coumarin appended 1,3-oxazines as potent antimicrobial and antioxidant agents

A convenient protocol for the synthesis of coumarin appended 1,3-benzoxazine derivatives (4a — 4g) is described. Cyclisation of hydrazones (3a — 3g) using triphosgene in dichloromethane gave the corresponding 1,3-oxazines in a relatively good yield. The proposed structures of newly synthesized compounds were confirmed by spectral methods and elemental analysis. Oxazine derivatives 4a — 4g were evaluated for their in vitro antimicrobial activity against various bacteria and fungi. Compounds 4b and 4d inhibited growth of test microbes thus proving significant antimicrobial activity. In addition, in vitro antioxidant activity of the synthesized compounds was evaluated and compared to that of standards, showing DPPH, NO, and OH radical scavenging properties. Compounds 4b and 4f exhibited higher antioxidant activity than a standard drug