Facile synthesis and antibacterial evaluation of 2-phenyl-3, 4-dihydro-2h-1, 3-benzoxazine derivatives

Abstract

A method for the synthesis of 3,4-dihydro-1,3-benzoxazines that involves the neat reaction of salicylaldehyde and benzyl amine to give an imine followed by reduction of the imine to a 2-(aminomethyl) phenol derivative and subsequently cyclisation through a reaction with various benzaldehydes is reported. The highlights of this procedure include the short reaction times, easy work-up methods and the reliance on recrystallization for the purification of the products. The 1, 3-benzoxazines were prepared in yields of 51-75% over the three steps. The prepared 1, 3-benzoxazines showed promising activity against gram negative bacteria Salmonella enterica, and Klebsiella pneumonia as compared to the reference antibiotic gentamycin.