Advances towards Highly Active and Stereoselective Simple and Cheap Proline-Based Organocatalysts
作者:Francesco Giacalone、Michelangelo Gruttadauria、Paola Agrigento、Paolo Lo Meo、Renato Noto
DOI:10.1002/ejoc.201000913
日期:2010.10
at loadings of 2–0.1 mol-% for the direct asymmetric aldol reaction in water by using variable amounts of water. Among them, a new catalyst, the L-proline carrying a trans-4-(2,2-diphenylacetoxy) group, and a catalyst previously synthesized by us, the L-proline carrying a trans-4-(4-phenylbutanoyloxy) group, were found to be excellent catalysts for the aldol reaction between cyclohexanone or cyclopentanone
通过使用不同量的水,筛选出 10 种 4-酰氧基-L-脯氨酸作为催化剂,负载量为 2-0.1 mol-%,用于在水中的直接不对称羟醛反应。其中,新型催化剂L-脯氨酸带有反式4-(2,2-二苯基乙酰氧基)基团,以及我们之前合成的催化剂L-脯氨酸带有反式4-(4-苯基丁酰氧基)基团, 被发现是环己酮或环戊酮与取代苯甲醛之间羟醛反应的优良催化剂,当分别以 1 和 0.5 mol-% 在室温下使用时,没有添加剂。对于此类催化剂,获得了高转化率,这是烯胺有机催化获得的最高值之一。最后,这些催化剂可以通过廉价分子的直接 O-酰化合成,并成功用于放大反应。