期刊
ORGANIC & BIOMOLECULAR CHEMISTRY
卷 10, 期 18, 页码 3730-3738出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c2ob00049k
关键词
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资金
- National Undergraduate Innovative Test Program [091063503]
- Natural Science Foundation of China (NSFC) [20872120]
- Municipal Science Foundation of Chongqing City (CSTC) [2009BB5110]
A series of pyrrolidine-based organocatalysts which bear three synergistic features, i.e. secondary amino group, various H-bond donor groups at the 4-position and a stereocontrol silyl ether group at the alpha-position of the pyrrolidine nitrogen atom, were developed. They were screened in anti-Mannich reactions of carbonyl compounds with preformed or in situ generated N-protected alpha-imino ethylglyoxylate and aldehydes with preformed or in situ generated N-carbamoyl imines. The influence of H-bond donor ability at the 4-position was also investigated. Among all the catalysts, 2a was identified as a general efficient organocatalyst suitable for various types of anti-Mannich reactions and broad substrate scope. Excellent results (up to 98% yield, >99% ee and >99 : 1 dr) were achieved with 5 mol% catalyst load. Sulfones with ortho substituents or very strong withdrawing groups on the aromatic ring, which have been regarded as challenging substrates in the direct anti-Mannich reactions of aldehydes with in situ generated N-carbamoyl imines, also worked well. The optimization of our catalytic system also offered alternative and easily operational protocols to access anti-Mannich products with orthogonal N-Boc or N-Cbz protecting groups.
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