New Regio- and Stereoselective Cascades via Unstabilized Azomethine Ylide Cycloadditions for the Synthesis of Highly Substituted Tropane and Indolizidine Frameworks
作者:Shuming Chen、Vlad Bacauanu、Tobias Knecht、Brandon Q. Mercado、Robert G. Bergman、Jonathan A. Ellman
DOI:10.1021/jacs.6b08355
日期:2016.9.28
Multisubstituted tropanes and indolizidines have been prepared with high regio- and stereoselectivity by the [3+2] cycloaddition of unstabilized azomethineylides generated from readily prepared trimethylsilyl-substituted 1,2-dihydropyridines via protonation or alkylation followed by desilylation. Starting from 1,2-dihydropyridines bearing a ring trimethylsilyl substituent at the 6-position, an intermolecular
Propargylsilanes as Reagents for Synergistic Gold(I)‐Catalyzed Propargylation of Carbonyl Compounds: Isolation and Characterization of σ‐Gold(I) Allenyl Intermediates
Reported herein is the isolation and characterization, for the first time, of a σ‐gold allenyl complex as an intermediate in gold catalysis. This intermediate was captured during the study of a novel gold(I)‐catalyzed propargylation of carbonyl compounds with propargylsilanes. Notably, the gold‐catalyzed propargylation reaction, which proceeds with aldehydes and ketones, can be driven to the formation
One-pot synthesis of 2-methylfurans from 3-(trimethylsilyl)propargyl acetates promoted by trimethylsilyl trifluoromethanesulfonate
作者:Danielle E. Sklar、Alex V. Helbling、Yiqi Liu、C. Wade Downey
DOI:10.1016/j.tetlet.2021.153424
日期:2021.12
In the presence of trimethylsilyl trifluoromethanesulfonate (TMSOTf) and triethylamine, 3-(trimethylsilyl)propargyl carboxylates undergo a one-pot alkylation-cyclization-desilylation reaction with ketones to produce 2-methylfurans. Alkylation at 0 °C in methylene chloride, followed by acid-catalyzed cyclization at room temperature, provides the furans in 52–86% yield. Cyclization and desilylation appear
在三氟甲磺酸三甲基甲硅烷基酯 (TMSOTf) 和三乙胺的存在下,羧酸 3-(三甲基甲硅烷基)炔丙基酯与酮进行一锅烷基化-环化-脱甲硅烷基化反应,生成 2-甲基呋喃。在 0 °C 下在二氯甲烷中烷基化,然后在室温下酸催化环化,以 52-86% 的产率提供呋喃。环化和脱甲硅烷基化似乎由在初始取代反应完成后将反应混合物暴露于水中而原位生成的三氟甲磺酸促进。
A facile stereoselective synthesis of (E)-α-silylvinyl sulfides via hydromagnesiation of alkynylsilanes
作者:Mingzhong Cai、Jun Xia、Pingping Wang
DOI:10.1002/hc.20165
日期:——
Hydromagnesiation of alkynylsilanes 1 in diethyl ether gave (Z)-α-silylvinyl Grignard reagents 2, which reacted with arylsulfenyl chlorides 3 to afford stereoselectively (E)-α-silylvinylsulfides 4 in good yields. (E)-α-Silylvinylsulfides 4 could undergo the cross-coupling reactions with Grignard reagents in the presence of NiCl2(PPh3)2 to give stereoselectively (Z)-1,2-disubstituted vinylsilanes
Pd-catalyzed sp–sp<sup>3</sup> cross-coupling of benzyl bromides using lithium acetylides
作者:Anirban Mondal、Paco Visser、Anna M. Doze、Jeffrey Buter、Ben L. Feringa
DOI:10.1039/d1cc02762j
日期:——
Organolithium-based cross-couplingreactions have emerged as an indispensable method to construct C–C bonds. These transformations have proven particularly useful for the direct and fast coupling of various organolithium reagents (sp, sp2, and sp3) with aromatic (pseudo) halides (sp2). Here we present an efficient method for the cross-coupling of benzyl bromides (sp3) with lithium acetylides (sp). The reaction proceeds