Highly Diastereoselective 1,4-Addition of an Organocuprate to Methyl α-<scp>d</scp>-Gluco-, α-<scp>d</scp>-Manno-, or α-<scp>d</scp>-Galactopyranosides Tethering an α,β-Unsaturated Ester. Novel Asymmetric Access to β-C-Substituted Butanoic Acids
作者:Kiichiro Totani、Takayuki Nagatsuka、Shuhei Yamaguchi、Ken-ichi Takao、Shigeru Ohba、Kin-ichi Tadano
DOI:10.1021/jo0101860
日期:2001.9.1
yields. Other organocuprates also serve as effective carbon nucleophiles for the 1,4-addition. Removal of the carbohydrate moiety from each adduct afforded a variety of beta-C-substituted butanoic esters in remarkable enantiomeric excess. The 1,4-addition of the same cuprate to some methyl alpha-D-manno- or alpha-D-galactopyranosidic substrates in which a crotonyl group was incorporated, each at 3-OH
由乙烯基溴化镁和溴化亚铜制备的1,4-二乙烯基铜镁酸加到甲基α-D-吡喃葡萄糖苷的一些4-O-巴豆酰基衍生物中,可以高水平地进行非对映化学诱导,从而提供了良好至优异收率的加合物。其他有机铜酸盐也可作为有效的碳亲核试剂用于1,4-加成。从每个加合物中除去碳水化合物部分,得到了各种对映体过量的β-C-取代的丁酸酯。还研究了相同的铜酸盐在一些甲基α-D-甘露聚糖或α-D-吡喃半乳糖苷底物中的1,4-加成,每个底物中并入了巴豆酰基,各自在3-OH上。当某些D-甘露聚糖类型的底物经受1,4-添加条件类似于用于D-葡萄糖型底物的条件。此外,一些D-半乳糖型底物提供具有更高非对映选择性的1,4-加合物。