Evidence for protonated cyclopropane intermediates in the deamination of 1-propylamine and mechanistic implications of protonated cyclopropanes

Abstract

Abstract The NMR examination of the 1-propanol and 2-propanol obtained from the nitrous acid deamination of 2,2-d2-1-propylamine, and the isotope position rearrangements observed in the 1-propanol fraction from similar deamination studie with 1-t-1-propylamine and 1-14C-1-propylamine showed that about 4–6% of the 1-propanol recovered was derived from protonated cyclopropane intermediates in which all three carbon positions became practically equivalent. A previously suggested direct 1,3-hydride shift as well as the possibility of successive 1,2-hydride shits have been eliminated. Consideration of the evidence obtained, together with known data from the literature, suggests that equilibration of edge-protonated cyclopropanes may be the best representation of the reactive intermediates responsible for the observed isotopic rearrangements in the 1-propanol from the deamination of 1-propylamine. Probable mechanistic implications of protonated cyclopropanes are discussed.