Experimental and theoretical investigation on the cycloadditions of nitrile oxides, nitrones, and diazoalkanes with acyclic vinyl sulphones and thiet 1,1-dioxide

Abstract

Diazoalkanes, nitrile oxides, and nitrones cycloadd thiet 1,1-dioxide showing regiochemical characteristics markedly different from those observed for acyclic vinyl sulphones. The charge-transfer stabilization energy, calculated according to the Klopman–Salem perturbational approach in the CNDO/2 approximation, is able to account for the experimental trends of the isomer ratios. An analysis of the calculations performed for cis-syn-vinyl sulphones explains the change of regiochemistry in the reactions of thiet 1,1 dioxide as due to its blocked cis-syn-structure which dues not happen in the ‘open’ vinyl sulphones. Unsuccessful predictions obtained with the frontier orbital approximation are discussed.