Nitrenes-XV: 1-Hydroxymethyl-4,5-dimethoxy-7H-azirino[1,2-a]-indole-7a-carboxylic acid γ-lactone,a nitrene addition compound

Triethyl phosphite deoxygenation of α-(6-nitroveratrylidene)-γ-butyrolactone 1 under moderate conditions affords a mixture of 3-(6-nitroveratryl)-2(5H)-furanone 5, α-(6-ethylaminoveratrylidene)-γ-butyrolactone 6 and 1-hydroxymethyl-4,5-dimethoxy-7H-azirino1,2-a]indole-7a-carboxylic acid γ-lactone 7, in addition to 3,4-dihydro-7,8-dimethoxy1,3-a]oxazino3,4-a]indol-1-one 2, ethyl 5,6-dimethoxyindole-2-carboxylate 3, and 2,3-dihydro-6,7-dimethoxyfuro2,3-b]quinoline 4, obtained under more drastic reaction conditions.The isolation of lactones 5 and 7 provides strong evidence for the intermediacy of nitrenes in this reaction which appears to provide the first example of intramolecular aziridine formation from a nitro-aromatic compound and triethyl phosphite.