Piezochemical interpretation of (C ⋯ H ⋯ X) hydrogen transfer in ene reactions

Abstract

Measurement of volumes of activation has provided mechanistic information about ene reactions involving (C ⋯ H ⋯ X) hydrogen transfer (X = O, C, and N). Depending on the nature of the reactants, the mechanism can range from a rate-limiting abstraction of the allylic hydrogen, through a concerted reaction (C ⋯ H ⋯ O ene reactions) to a probable stepwise process with the rate-limiting C–N bonding at the first stage and hydrogen transfer at the second one (C ⋯ H ⋯ N transfer reactions).