Heteroaromatic annulation studies on 10,11-dihydro-11-[bis(methylthio)methylene]dibenzoxepin-10-one: a facile access to novel dibenzoxepino[4,5]-fused heterocycles

10,11-Dihydro-11-[bis(methylthio)methylene]dibenzoxepin-10-one has been shown to be a useful three carbon synthon for the efficient regiospecific annulation of a variety of five- (pyrazoles, isoxazoles, thiophene, and γ-lactone) and six-membered (pyrimidines, pyridone and pyridines) heterocycles by cyclocondensation with heterobinucleophiles such as hydrazine, hydroxylamine, dimethylsulfonium methylide, guanidine, thiourea, cyanoacetamide, and substituted β-lithioaminoacrylonitrile.