Substituted heterocycles are privileged scaffolds due to their existence in varieties of natural products and bioactive important molecules, widely applied in pharmacy and organic chemistry, serving as functional materials. Recently, diversity-oriented synthesis (DOS) has received considerable attention for achieving structural diversity along with structural complexity. On the basis of DOS concept and forward-synthetic analysis, a facile and versatile Lewis acid mediated cascade cyclization and ionic hydrogenation strategy has been developed successfully. With the utilization of Al(OTf)3/Et3SiH reagent system, various heterocycle building blocks were synthesized in moderate to good yields, including pyrrolindinones, piperidones, isoindoline, dihydro-1,4-benzoxazepinones, dihydro-1,4-benzoxazines, tetrahydroquinoline, 2,3-dihydroindoles, lactones and other structure related heterocycles. Furthermore, this protocol was utilized to smoothly prepare piracetam and its key intermediate as well. In general, extensive functional groups tolerance, mild reaction conditions and favorable efficiency ensure the promising prospect of this diversity-oriented synthetic protocol in organic synthesis.

Diversity-oriented synthesis of heterocycles: Al(OTf)3- promoted cascade cyclization and ionic hydrogenation

256th National Meeting (2018)

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