Synthesis and Reactivity of A new Pyranoquinoxaline

摘要

3-Methyl-3,4-dihydro-1H-pyrano[3,4-b]quinoxalin-1-one (2) was prepared from a series of 3-methyl-4,5,10,l1-tetrahydropyrano[4,3-b][l,5]benzo-diazepin-l(3H)-one derivatives (1) bearing various substituents at position 11.The formation of this quinoxaline is initiated by oxidation of the diazepine-4',11'-double bond to give an unstable epoxide intermediate,followed by a ring contraction which releases a carben species that has been trapped in the presence of cyclohexene.Reactivity of this new quinoxaline (2) with various primary and secondary amines was investigated.