Pyridines have occupied a unique position in the design and synthesis of novel biologically active agents that exert remarkable antiulcer, antifungal, antihyperglycemic, antileukemic, anti-alzheimer, anti-HIV and anticancer activities. Many synthetic methods have been developed for the synthesis of pyridines and new approaches still continue to appear stimulated by the broad spectrum of biological activity of such compounds. Electrophilic cyclization has recently emerged as valuable tool in organic synthesis. We have shown that upon treatment with molecular iodine, N-propargylic �-enaminones 2 , prepared readily from acetylenic ketones 1 , undergo electrophilic cyclization to afford 4-iodopyridine derivatives 3  in good to high yields. The resulting iodine-containing products have been further elaborated to a wide range of functionally substituted pyridines using subsequent metal-catalyzed coupling processes. The scope, limitations and mechanism of these reactions will be discussed.

Synthesis of pyridines via electrophilic cyclization of <i>N</i>-propargylic β-enaminones

243rd National Meeting (2012)

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Synthesis of pyridines via electrophilic cyclization of N-propargylic β-enaminones