Novel Cyclization of Vinyl Nitrene into 1-Azaphenalene

Abstract

Thermal reaction of 2H-azirines, bearing a methoxy or methylthio group at the neighboring position to azirine ring, was studied. In thermolysis of ethyl 2-(2-methoxynaphth-1-yl)-2H-azirine-3-carboxylate, attack of the vinyl nitrene at the peri position to form a 1-azaphenalene ring was observed. In thermal reaction of its thio analogue, 1-azaphenalene was also formed, but a naphthothiazine formed by the attack of vinyl nitrene at the sulfur atom was the major product. Mechanisms and differences of the reactions depending on O and S are discussed.

Photochemistry of 2-(1-Naphthyl)-2H-azirines in Matrixes and in Solutions: Wavelength-Dependent C−C and C−N Bond Cleavage of the Azirine Ring

“…However, in the course of our studies of the reactivities of photolytically generated intermediates having an electron-withdrawing group, we found that irradiation of 3-methyl-2-(4-nitrophenyl)-2 H -azirine caused the cleavage of not the C−C bond but C−N bond of the azirine ring selectively . This is the first observation of the C−N bond cleavage in the photochemistry of 2 H -azirines, although it was reported that thermolysis of 2-aryl-2 H -azirines yielded products derived from the C−N bond cleavage . This finding reawakened interest in the photochemistry of 2 H -azirines, leading us to investigate as to whether the C−N bond cleavage could be observed in the photochemistry of 2 H -azirines other than the azirine having a 4-nitrophenyl group.…”