Novel supramolecular organocatalysts of hydroxyprolinamide based on calix[4]arene scaffold for the enantioselective Biginelli reaction
作者:ZhengYi Li、HuaiJie Xing、GuoLi Huang、XiaoQiang Sun、JuLi Jiang、LeYong Wang
DOI:10.1007/s11426-011-4374-z
日期:2011.11
A series of novel supramolecular organocatalysts of hydroxyprolinamide based on the upper rim of calix[4]arene scaffold have been developed to catalyze enantioselective multi-component Biginelli reaction. Under the optimal conditions, the reactions occurred with moderate-to-excellent enantioselectivities (up to 98% ee). A plausible transition state constructed by the supramolecular interaction of hydrogen bond and cation-π between catalysts and substrates has been proposed.
Bifunctional primary amine-thiourea–TfOH (BPAT·TfOH) as a chiral phase-transfer catalyst: the asymmetric synthesis of dihydropyrimidines
作者:Yangyun Wang、Jipan Yu、Zhiwei Miao、Ruyu Chen
DOI:10.1039/c0ob01268h
日期:——
An enantioselective Biginelli reaction has been developed by using a bifunctional primary amine-thioureaâTfOH (BPAT·TfOH) as a chiral phase-transfer catalyst and t-BuNH2·TFA as an additive in saturated brine at room temperature. The corresponding dihydropyrimidines were obtained in moderate-to-good yields with up to 99% ee under mild conditions. A plausible transition state has been proposed to explain the origin of the activation and the asymmetric induction.
An enantioselectiveBiginellireaction that proceeds by a dual-activation route has been developed by using a combined catalyst of a readily available trans-4-hydroxyproline-derived secondary amine and a Bronsted acid. Aromatic, heteroaromatic, and fused-ring aldehydes were found to be suitable substrates for this multicomponent reaction. The corresponding dihydropyrimidines were obtained in moderate-to-good