The Tungsten-Promoted Dearomatization of N-Sulfonyl Pyridinium Salts for Novel Organic Synthesis

This works describes the development of a second generation N-sulfonyl pyridinium dihapto bound to a WTp(NO)(PMe3) fragment. In addition to preserving the chemistry demonstrated by the first generation N-acetyl system without rotational isomers, this novel system demonstrated unprecedented reactivity pathways including a Zincke-like ring-opening of carbon substituted dihydropyridines and an acid-promoted scission of tetrahydropyridines. Additionally, these sulfonyl systems were applied in the synthesis of bicyclic alkaloids, piperidyl-substituted analogues of Ritalin, and deuterated tetrahydropyridines.