Synthesis of new series of 5,6-dihydro-4H-1,2-oxazines via hetero Diels-Alder reaction and evaluation of antimicrobial activity

A new series of 5,6-dihydro-4H-1,2-oxazines were synthesized via hetero Diels-Alder reaction of α-nitrosoolefins with alkenes. α-Nitrosoolefins were generated from ketoximes by the action of chloramine-T. The newly synthesized compounds were characterized with IR, NMR, elemental analysis and screened for their antimicrobial activity; they exhibited excellent antimicrobial activity. The minimal inhibitory concentration of the compounds was in the range of 10-35 μg ml^-1 for bacteria and 10-40 μg ml^-1 for fungi.