在富电子芳族化合物与儿茶酚硼烷的亲电CHH硼化反应中,亲电硼的催化生成是由各种Lewis和Brønsted酸对BH键的杂化作用引发的,它仅形成硼离子。配体解离后,相应的硼离子在苯胺衍生物以及含氮杂环上进行区域选择性亲电芳香取代。使用B(C 6 F 5)3来优化催化作用作为引发剂,并且在不添加外部碱或二氢受体的情况下进行。为了确保这些Friedel-Crafts型反应的有效转换,通常需要高于80°C的温度。机理实验表明,释放氢的硼/硼离子的再生是决定速率的。这一发现最终导致人们发现,添加烯烃后,催化CHH硼化可以首次在室温下进行。
Remarkable Effect of N-Substituent on Enantioselective Ruthenium-Catalyzed Propargylation of Indoles with Propargylic Alcohols
摘要:
Ruthenium-catalyzed enantioselective propargylation of indoles with propargylic alcohols affords the corresponding beta-propargylated indoles in good yields with a high enantioselectivity (up to 95% ee). A remarkable effect of the nature of the N-substituent of indoles is observed for the enantioselectivity of the propargylated indoles. The preparative method described in this paper may provide a novel protocol for asymmetric Friedel-Crafts alkylation of indoles using propargylic alcohols as a new type of electrophiles.
Pinacol Boronates by Direct Arene Borylation with Borenium Cations
作者:Alessandro Del Grosso、Paul J. Singleton、Christopher A. Muryn、Michael J. Ingleson
DOI:10.1002/anie.201006196
日期:2011.2.25
Borenium does it direct: A boron analogue of the Friedel–Crafts reaction uses inexpensive catecholatoborenium cations that are sufficiently electrophilic to borylate arenes by electrophilic aromatic substitution. The direct arene borylation proceeds with high regioselectivity for a range of anilines, N‐heterocycles, and thiophenes. Subsequent one‐pot transesterification provides the synthetically useful
Rational Ligand Design for the Arylation of Hindered Primary Amines Guided by Reaction Progress Kinetic Analysis
作者:Paula Ruiz-Castillo、Donna G. Blackmond、Stephen L. Buchwald
DOI:10.1021/ja512903g
日期:2015.3.4
We report the Pd-catalyzed arylation of very hindered α,α,α-trisubstituted primary amines. Kinetics-based mechanistic analysis and rational design have led to the development of two biarylphosphine ligands that allow the transformation to proceed with excellent efficiency. The process was effective in coupling a wide range of functionalized aryl and heteroaryl halides under mild conditions.
Ruthenium-catalyzed enantioselective propargylation of l-(triisopropylsilyl)-1H-indoles with propargylicalcohols gives the corresponding β-propargylated indoles in good yields with high enantioselectivity. Reactions with l-(l-naphthyl)prop-2-yn-l-ol achieve the highest enantioselectivity (up to 95% ee).
Au-Catalyzed Cross-Coupling of Arenes via Double C–H Activation
作者:Xacobe C. Cambeiro、Nanna Ahlsten、Igor Larrosa
DOI:10.1021/jacs.5b10593
日期:2015.12.23
The first methodology for Au(I/III)-catalyzed oxidative cross-coupling of arenes via double C-H activation has been developed. The reaction is fully selective for the cross-coupling between electron-rich hetero-/carbocyclic arenes and electron-poor arenes bearing relatively acidic C-H bonds: The inherently high cross-selectivity of the system obviates the need for directing groups or a large excess of one of the coupling partners.