Decomposition of 2-azidosulphonylbenzophenones. Unusual rearrangement products

Abstract

Thermal decomposition of 2-azidosulphonylbenzophenones gives the 7-membered cyclisation products in addition to products in which nitrogen is bound to the ortho-position originally bearing the carbonyl group; ring chain tautomerism of the sulphonyl azides with 3-aryl-3-azidobenzo[d][2,1]oxathioles followed by decomposition of the latter and 1,2-aryl shifts is proposed to explain formation of the rearranged products.