Structural Characterization of N-Protonated Amides. Regioselective N-Protonated Amides. Regioselective N-Activation of Medium-Bridged Twisted Lactams

This document is the Accepted Manuscript version of a Published Work that appeared in final form in the Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://doi.org/10.1021/ja101690u.The straightforward protonation of lactams by treatment with acid and the full structural characterization of three resulting N-protonated lactams are disclosed. This work provides experimental evidence that N-protonation of amide bonds results in a dramatic increase of non-planarity about the C-N amide bond. The resulting compounds are discussed in structural, spectroscopic, and reactivity terms. The data suggests that ca. 50° distortion of these amide bonds suffices for their efficient N-activation