American Chemical Society
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Chiral Brønsted Acid-Catalyzed Direct Asymmetric Mannich Reaction

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journal contribution
posted on 2007-04-04, 00:00 authored by Qi-Xiang Guo, Hua Liu, Chang Guo, Shi-Wei Luo, Yi Gu, Liu-Zhu Gong
A chiral Brønsted acid-catalyzed direct asymmetric Mannich reaction has been described. Various phosphoric acids, prepared from BINOL and H8-BINOL derivatives, have been evaluated for catalyzing the direct Mannich reaction. In the presence of a truly catalytic amount of the phosphoric acid, anti-selective Mannich reactions of cyclic ketones with a wide scope of aldimines were obtained in high yields with excellent enantioselectivities (up to 98% ee) and high diastereomeric ratios (up to 98/2 dr). A one-pot Mannich reaction using aromatic ketones as donors proceeded smoothly to give β-amino carbonyls with fairly good enantioselectivities.