Stereoselective Synthesis and Retentive Trapping of α-Chiral Secondary Alkyllithiums Leading to Stereodefined α,β-Dimethyl Carboxylic Esters
作者:Varvara Morozova、Kohei Moriya、Peter Mayer、Paul Knochel
DOI:10.1002/chem.201601911
日期:2016.7.11
leads to the corresponding secondary alkyllithiums with high retention of configuration. Subsequent quenching with various electrophiles such as Bu2S2, DMF, MeOB(OR)2, or Et2CO provides the desired products with retention of configuration. Furthermore, a transmetalation with CuBr⋅P(OEt)3 also allows retentive trapping with acid chlorides and ethylene oxide. The quenching of the resulting alkyllithiums
在-100°C下用t BuLi处理α-手性仲烷基碘化物,可以得到相应的具有高构型保留性的仲烷基锂。随后用诸如Bu 2 S 2,DMF,MeOB(OR)2或Et 2 CO的各种亲电试剂淬灭,可提供所需的产物,并保留其构型。此外,用CuBr⋅P(OEt)3进行金属转移也可以用酰氯和环氧乙烷进行保持性捕集。用ClCO 2 Et淬灭生成的烷基锂,可立体选择性合成和反合成-2-乙基-2-甲基丙烯酸二乙酯羧酸盐(dr> 94%)。还制备了带有三个相邻立体控制中心(立体三单元)的相关酯。该方法已应用于以市场上可买到的顺式-2,3-环氧丁烷开始的dr = 97:3的总产率为26%的蚂蚁信息素(±)-紫杉醇的合成(四个步骤)。