LAUSR

Abstract The chemo-, regio- and stereoselectivities of the formation of spiroheterocycles via the (3 + 2) cycloaddition (32CA) reaction of 1-methyl-3-(2,2,2-trifluoroethylidene) pyrrolidin-2-one (A1) derivatives with diazomethane and nitrone derivative have been studied at the M06–2X/6-311G level of theory. The reactions of diazomethane (A2) and N-methyl-C-phenyl nitrone (A3) derivatives with 1-methyl-3-(2,2,2-trifluoroethylidene)pyrrolidin-2-one derivatives (A1) occurs chemoselectively along the olefinic bond of A1 via an asynchronous one-step mechanism. Substituents on A3 do not affect the selectivity of reaction whereas the electronic and steric nature of the substituent on A2 does. The title reaction proceeds via forward electron density flux (FEDF), where electron density fluxes from the three-atom components to A1. The global electron density transfer (GEDT) values suggest that the 32CA of A1 with diazomethane is a polar reaction while the 32CA reaction of A1 with N-methyl-C-phenyl nitrone is a non-polar reaction, and an inverse relationship has been established between the polar character of the reactions and activation barriers.