A rare one-pot reaction, a tandem [1,5]-H shift/1,5 electrocyclization/[3 + 2] cycloreversion process, leading from N-[2-(1,3-oxathiolan-2-yl)]phenyl ketenimines to 1-(beta-styryl)-2,1-benzisothiazol-3-ones and ethylene, is disclosed and mechanistically unraveled by means of a computational DFT study. The two latter stages of the tandem process are calculated to occur in a single mechanistic step via a transition structure of pseudopericyclic characteristics.
Tandem 1,5-Hydride Shift/1,5-S,N-Cyclization with Ethylene Extrusion of 1,3-Oxathiolane-Substituted Ketenimines and Carbodiimides. An Experimental and Computational Study
of the mechanism is rather peculiar, combining a 1,5-cyclization by S−N bond formation, aromaticity recovery at the benzene nucleus, and the fragmentation of the oxathiolane framework originating a new carbonyl group. It can be related with a vinylogous retro-ene reaction and shows pseudopericyclic characteristics. The computations also revealed that the alternative 6π electrocyclization of the transient