Quantum chemical study of alcoholysis mechanism of N-methyl-1,2-thiazetidine-1,1-dioxide

Abstract

The alcoholysis of N-methyl-1,2-thiazetidine-1,1-dioxide has been investigated using ab initio and density functional theory. The geometries, energies and frequencies of reactants, intermediates, transition states and products are calculated. Our results indicate the alcoholysis of N-methyl 1,2-thiazetidine 1,1-dioxide proceeds via two reaction channels. Channel I is the cleavage of bond C–S and producing N-methyl- N-ethyl amino-methyl sulfonate (P1, in Fig. 1) in which attacking of CH 3OH and breaking of bond C–S are concerted. Channel II is the cleavage of bond S–N and producing 2-( N-methyl) taurine methyl ester (P2, in Fig. 1) in which there are two reaction processes with two different mechanism: concerted and stepwise. The most favorite pathway for alcoholysis of N-methyl 1,2-thiazetidine 1,1-dioxide was found. The energy barrier of the cleavage of C–S bond and producing P1 is the highest among them. We think that this may be the possible reason of having no experimental evidence on the formation of product P1.