Chiral Bicyclic Guanidine as a Versatile Brønsted Base Catalyst for the Enantioselective Michael Reactions of Dithiomalonates and β-Keto Thioesters
作者:Weiping Ye、Zhiyong Jiang、Yujun Zhao、Serena Li Min Goh、Dasheng Leow、Ying-Teck Soh、Choon-Hong Tan
DOI:10.1002/adsc.200700326
日期:2007.11.5
A chiral bicyclic guanidine was developed as a versatile Brønsted base catalyst for the enantioselective Michael reactions of dithiomalonates and β-keto thioesters using a range of acceptors including maleimides, cyclic enones, furanone and acyclic 1,4-dicarbonylbutenes.
Rate Acceleration of Triethylamine-Mediated Guanidine- Catalyzed Enantioselective Michael Reaction
作者:Zhiyong Jiang、Weiping Ye、Yuanyong Yang、Choon-Hong Tan
DOI:10.1002/adsc.200800423
日期:2008.10.6
bicyclic guanidine was found to be an excellent catalyst for enantioselectiveMichaelreactions. It was observed that additives such as non-chiral amines could accelerate the rate of reaction. When triethylamine (Et3N) was as used as the solvent, the reactionrate can be increased up to 1000 times without compromising the enantioselectivity. Michael acceptors such as 2-cyclopenten-1-one 2 and N-alkylmaleimides