Physical Sciences and Mathematics Commons^™

Catalysis Of The Aza-Diels-Alder Reaction By Hydrogen And Halogen Bonds, Vincent De Paul Nzuwah-Nziko, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The combination of H2C=NH and cis-1,3-butadiene to form a six-membered ring was examined by quantum calculations. The energy barrier for this reaction is substantially lowered by the introduction of an imidazolium catalyst with either a H or halogen (X) atom in the 2-position, which acts via a H or halogen bond to the N atom of the imine, respectively. X=I has the largest effect, and Cl the smallest; Br and H are roughly equivalent. The catalyst retards the formation of the incipient N-C bond from imine to diene while simultaneously accelerating the C-C bond formation. The energy of the π* …