Catalyst-Free Thia-Michael Addition to α-Trifluoromethylacrylates for 3D Network Synthesis

Thia-Michael additions (1,4-additions of a thiol to a Michael acceptor) are generally catalyzed by an external Bronsted or Lewis base. A spontaneous (uncatalyzed) Michael addition of thiols to alpha-trifluoromethyl acrylates is described, as well as its application to the very efficient preparation of a thermoset. A thorough mechanistic investigation, based on an experimental kinetic study and on DFT calculations, is presented for the addition of arene- and alkanethiols to tert-butyl trifluoromethyl acrylate in polar aprotic solvents, unveiling a probable solvent-assisted proton transfer in the rate-determining step and a considerable lowering of the energy barrier induced by the CF3 group.

Automated summary

This study describes a spontaneous (uncatalyzed) Michael addition of thiols to alpha-trifluoromethyl acrylates and its efficient application in the preparation of a thermoset. Mechanistic investigation reveals a probable solvent-assisted proton transfer in the rate-determining step and a considerable lowering of the energy barrier induced by the CF3 group in the addition of arene- and alkanethiols to tert-butyl trifluoromethyl acrylate in polar aprotic solvents.