3H-azepines and related systems. Part 2. The photolyses of aryl azides bearing electron-withdrawing substituents

Abstract

The photolyses of ortho-substituted aryl azides (o-XC₆H₄N₃ where X = CONHNH₂, CONHNCHAr, NO₂, CN, CF₃, SO₂OMe, SO₂NH₂, or SO₂Ph) in methanol–tetrahydrofuran solution are described. With X = CF₃ or CONHNCHAr, 3-substituted 2-methoxy-3H-azepines are products, while in other cases polymeric products, amines, or mixtures of isomeric azepines are obtained. The product from the photolysis of o-azidophenyl phenyl sulphoxide (X = SOPh) is identified tentatively (n.m.r. evidence) as 7-methoxy-2-phenylsulphinyl-3H-azepine.

In contrast, methyl p-azidobenzoate and p-cyanophenyl azide yield the corresponding 5-substituted 2-methoxy-3H-azepines, whereas methyl m-azidobenzoate yields only methyl 2-methoxy-3H-azepine-6-carboxylate. Irradiation of methyl o-azidobenzoate in aqueous tetrahydrofuran gives 1,3-dihydro-3-methoxycarbonyl-2H-azepin-2-one.