Transformation of 5,6,7,8-tetrahydro-2H-1-benzopyran-2,8-diones with hydrazines and hydrazoic acid:: Synthesis of 8-hydrazono-5,6,7,8-tetrahydro-2-oxo-2H-1-benzopyrans, pyrano[2,3-c]azepines and pyrido[2,3-c]azepines

N-(5,6,7,8-Tetrahydro-2,5-dioxo-2H-1-benzopyran-3-yl)benzamide (1a) reacts with nitrogen-containing nucleophiles (2) (hydrazines and hydroxylamine) to give the corresponding 8-hydrazono derivatives (3a-i) and the related hydroxyimino derivative (3j). The action of hydrazoic acid on 1a-b or 3a-b and 3e resulted in the formation of pyrano[2,3-c]azepines (4a-b). The pyranoazepine (4a) can be debenzoylated to 4b or transformed into pyrido[2,3-c]azepines (5a-b).