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  • Title: Silicon-based Lewis acid assisted cinchona alkaloid catalysis: highly enantioselective aza-Michael reaction under solvent-free conditions.
    Author: Yang HM, Li L, Li F, Jiang KZ, Shang JY, Lai GQ, Xu LW.
    Journal: Org Lett; 2011 Dec 16; 13(24):6508-11. PubMed ID: 22087568.
    Abstract:
    The study showed that a combination of an achiral silicon-based Lewis acid and chiral Lewis base, such as iodotrimethylsilane (TMSI) and cinchonine, generated a highly enantioselective catalyst system under solvent-free conditions which gave aromatic β-amino ketones with up to >99% ee. Mechanistic studies demonstrate the enhanced asymmetric induction may be due to the combined and competitive activation of a carbonyl moiety of chalcone with cinchonine and the silicon-based Lewis acid in the aza-Michael reaction.
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