Photochemical reactions of diazodihydronaphthalenones in cyclic ethers

Abstract

Photolysis of 4-diazonaphthalen-1(4H)-one (1a), 2-methyl-4-diazonaphthalen-1(4H)-one (1b) and 4-diazo-2-nitronaphthalen-1(4H)-one (1c) in neat THF and 1,4-dioxane produced a variety of products depending on the 2-substituent and the solvent. While 1a and 1c produced predominantly insoluble copolymers in both solvents, 1b produced, besides small amounts of copolymers, a novel polyether bridged naphthalene, 2,3:11,12-bis(2-methyl-1,4-naphthylene)-18-crown-6 (2b), 1,4-dioxa-3′-methyl-4′-oxo-1′,4′-dihydronaphthalene-1′-spiro-5-cycloheptane (3b), 2-methyl-4-(1,4-dioxan-2-yl)naphthol (4b) and 2-methylnaphthol (5b) in dioxane, and 3′-methyl-4′-oxo-1′,4′-dihydronaphthalene-1′-spiro-2-pyrane (3b′), 2-methyl-4-(tetrahydrofuran-2-yl)naphthol (4b′) and 5b in THF. Compound 2b is characterised by X-ray crystallography.