Chemoselective Boron-Catalyzed Nucleophilic Activation of Carboxylic Acids for Mannich-Type Reactions
作者:Yuya Morita、Tomohiro Yamamoto、Hideoki Nagai、Yohei Shimizu、Motomu Kanai
DOI:10.1021/jacs.5b04175
日期:2015.6.10
The carboxyl group (COOH) is an omnipresent functional group in organic molecules, and its direct catalytic activation represents an attractive synthetic method. Herein, we describe the first example of a direct catalytic nucleophilic activation of carboxylic acids with BH3·SMe2, after which the acids are able to act as carbon nucleophiles, i.e. enolates, in Mannich-type reactions. This reaction proceeds
羧基 (COOH) 是有机分子中无处不在的官能团,其直接催化活化是一种有吸引力的合成方法。在此,我们描述了用 BH3·SMe2 直接催化亲核活化羧酸的第一个例子,之后酸能够在曼尼希型反应中充当碳亲核试剂,即烯醇化物。该反应使用温和的有机碱 (DBU) 进行,并表现出高水平的官能团耐受性。硼催化剂对 COOH 基团具有高度化学选择性,即使存在其他羰基部分,如酰胺、酯或酮。此外,通过使用 (R)-3,3'-I2-BINOL 取代的硼催化剂,这种催化方法可以扩展到高度对映选择性的曼尼希型反应。