Achiral Counterion Control of Enantioselectivity in a Brønsted Acid-Catalyzed Iodolactonization
作者:Mark C. Dobish、Jeffrey N. Johnston
DOI:10.1021/ja301858r
日期:2012.4.11
Highly enantioselective halolactonizations have been developed that employ a chiral proton catalyst-N-iodosuccinimide (NIS) reagent system in which the Brønsted acid is used at catalyst loadings as low as 1 mol %. An approach that modulates the achiral counterion (equimolar to the neutral chiral ligand-proton complex present at low catalyst loadings) to optimize the enantioselection is documented for
已经开发出高度对映选择性卤内酯化反应,它采用手性质子催化剂-N-碘代琥珀酰亚胺 (NIS) 试剂系统,其中布朗斯台德酸以低至 1 mol% 的催化剂负载量使用。在该转化中首次记录了一种调节非手性抗衡离子(与低催化剂负载下存在的中性手性配体-质子复合物等摩尔)以优化对映体选择的方法。通过这种方式,使用市售 NIS 将不饱和羧酸以高产率(高达 98% ee)转化为 γ-内酯。