Diastereoselective Syntheses of (<i>E</i>)-α-Trialkylsilyl α,β-Unsaturated Esters, α-Silane-Substituted Conjugated Silyl Ketene Acetals, and α,γ-Substituted Allylsilanes
作者:David A. Johnson、Amanda J. Mueller Hendrix、Michael P. Jennings
DOI:10.1021/acs.joc.8b01209
日期:2018.9.7
functionalization of propiolate esters via a catalytic carbocupration/silicon group migration sequence has been further investigated to include the syntheses of a wide variety of β-alkyl- and β-aryl-substituted (E)-α-silyl α,β-unsaturated esters. The ester substrates were transformed into their β,γ-unsaturated isomers by means of an LDA-mediated γ-deprotonation, extended silyl ketene acetal formation, and final
已进一步研究了通过催化碳汇/硅基团迁移序列对丙酸酯的邻位官能化,包括各种β-烷基-和β-芳基取代的E的合成。)-α-甲硅烷基α,β-不饱和酯。通过LDA介导的γ-去质子化,延长的甲硅烷基乙烯酮缩醛形成和最终的α-质子化序列,将酯底物转化为其β,γ-不饱和异构体。还分离了甲硅烷基乙烯酮缩醛中间体,并通过NOE建立了它们的立体化学。中间体延伸的甲硅烷基乙烯酮缩醛的分离提供了对锂延伸的二烯酸酯结构的进一步理解,并为Snieckus提出的在用金属二烷基酰胺使(Z)-α,β-不饱和羰基脱质子时的环状八元过渡态提供了额外的支持。