Thermal Effects in the Organocatalytic Asymmetric Mannich Reaction
作者:Belén Rodríguez、Carsten Bolm
DOI:10.1021/jo060064d
日期:2006.3.31
The proline-catalyzed direct asymmetricMannichreaction between cyclohexanone, formaldehyde, and various anilines is thermally accelerated. With only 0.5 mol % of catalyst, Mannich products with up to 98% ee have been obtained after a short period of time in reactions performed under microwave irradiation. In situ reduction of the resulting ketones affords N-aryl amino alcohols in up to 86% yield
The scope and limitations of the direct organocatalytic asymmetric α-aminomethylation of ketones are disclosed. The proline-catalyzed classical Mannich reactions between unmodified ketones, aqueous formaldehyde and aromatic amines furnished the desired Mannich bases in high yield with up to >99% ee. Moreover, methyl alkyl ketones were regioselectively α-aminomethylated at the methylene carbon affording