PYROLYSIS OF ARYL AZIDES .12. MECHANISTIC IMPLICATIONS OF THE VERY SMALL NEIGHBORING GROUP EFFECTS ACROSS THE 2,3-BOND OF 2-AZIDONAPHTHALENE

2-Azidonaphthalenes with nitro, acetyl, benzoyl and methoxycarbonyl su bstituents in the 3-position have been synthesized and then pyrolysed in nitrobenzene solution. At 120-degrees, the rates (relative to 2-azi donaphthalene) are respectively 27.9, 24.8, 5.00 and 3.67. These very small neighbouring group effects are consistent with a transition stat e which has considerable quinonoid character. No evidence of cyclic pr oducts was obtained from the two azides with nitro and ester neighbour ing groups. With the two azido ketones there was infrared spectroscopi c evidence of clean cyclization in dilute solution, to form the corres ponding naphth[2,3-c]isoxazole. Our attempts to isolate these two naph thisoxazoles led to decomposition, though 3-methylnaphth[2,3-c]isoxazo le has been reported previously (Friedrichsen and Kaschner 1977).1