Effect of Additives on the Stereochemical Integrity and Reactivity of α-Alkoxycarbonyl Alkenylcopper Intermediates. Optimal Conditions for the Synthesis of Isomerically Pure Tetrasubstituted Alkenes
作者:Na Zhu、Dennis G. Hall
DOI:10.1021/jo034465u
日期:2003.7.1
A systematic study on the effect of additives on the isomerizability of 1-alkoxycarbonyl alkenylcopper(I) intermediates revealed that the lithium chelator 12-crown-4 is significantly more efficient than HMPA at retarding isomerization. On the other hand, 12-crown-4 alone is unable to promote effective coupling with alkyl halides. The combination of 12-crown-4 and a reduced amount of HMPA, however,
对添加剂对1-烷氧羰基烯基铜(I)中间体的异构化影响的系统研究表明,锂螯合剂12-冠4在延缓异构化方面比HMPA有效得多。另一方面,单独的12-冠-4不能促进与卤代烷的有效偶联。然而,将12-冠-4和减少量的HMPA组合使用,导致了制备有用的,异构体纯的四取代烯烃如烯丙基化试剂和跳过的二烯的改进方法。