Synthesis and 13C NMR Spectroscopy of 13C-Labeled α,ω-Diphenylpolyynes
摘要:
The synthesis of three C-13-labeled alpha,omega-diphenylpolyynes is described. The known positions of the labeled carbon atoms allow assignment of the resonances in the C-13 NMR spectra and identification of trends in the chemical shifts.
Synthesis and 13C NMR Spectroscopy of 13C-Labeled α,ω-Diphenylpolyynes
摘要:
The synthesis of three C-13-labeled alpha,omega-diphenylpolyynes is described. The known positions of the labeled carbon atoms allow assignment of the resonances in the C-13 NMR spectra and identification of trends in the chemical shifts.
Mechanistic Aspects of Alkyne Migration in Alkylidene Carbenoid Rearrangements
作者:Paul Bichler、Wesley A. Chalifoux、Sara Eisler、Annabelle L. K. Shi Shun、Erin T. Chernick、Rik R. Tykwinski
DOI:10.1021/ol8023665
日期:2009.2.5
The mechanism of the Fritsch−Buttenberg−Wiechell rearrangement of 13C labeled precursors has been examined to determine the propensity of the alkynyl (R−C≡C−) group to migrate in an alkylidene carbenoid species. Reaction of dibromoolefins with n-BuLi and ketones with Me3SiC(Li)N2 both demonstrate that the alkynyl moiety readily undergoes 1,2-migration from carbenoid intermediates.
已经对13 C标记前体的Fritsch-Buttenberg-Wiechell重排机制进行了研究,以确定炔基(RC- C - C)基团在亚烷基类胡萝卜素物质中迁移的倾向。二溴烯烃与n- BuLi的反应与酮与Me 3 SiC(Li)N 2的反应均表明炔基部分易于从类胡萝卜素中间体进行1,2-迁移。