Electrochemical Nozaki–Hiyama–Kishi Coupling: Scope, Applications, and Mechanism
作者:Yang Gao、David E. Hill、Wei Hao、Brendon J. McNicholas、Julien C. Vantourout、Ryan G. Hadt、Sarah E. Reisman、Donna G. Blackmond、Phil S. Baran
DOI:10.1021/jacs.1c03007
日期:2021.6.30
practical using an electroreductive manifold. Although early studies pointed to the feasibility of such a process, those precedents were never applied by others due to cumbersome setups and limited scope. Here we show that a carefully optimized electroreductive procedure can enable a more sustainable approach to NHK, even in an asymmetric fashion on highly complex medicinally relevant systems. The e-NHK
最常用的 C-C 键形成方法之一是使用还原歧管,使卤乙烯与 Ni 和 Cr 催化的醛偶联(Nozaki-Hiyama-Kishi,NHK)变得更加实用。尽管早期研究指出了这种过程的可行性,但由于设置繁琐且范围有限,这些先例从未被其他人应用。在这里,我们展示了经过精心优化的电还原程序可以使 NHK 采用更可持续的方法,即使在高度复杂的医学相关系统上以不对称方式也是如此。当传统化学技术失败时,e-NHK 甚至可以使非规范底物类别(例如氧化还原活性酯)参与低负载量的 Cr。详细的动力学、循环伏安法、
A Cp2TiCl2-Me3Al (1 : 4) reagent system: An efficient reagent for generation of allylic titanocene derivatives from vinyl halides, vinyl ethers and carboxylic esters
Cp2TiCl2-Me3Al (a 1 : 4 ratio) reagent system in toluene for 3 days is found to be effective in generating allylic titanocene on treatment with vinyl halides, vinylethers and carboxylic esters in THF. The process for the generation of an allylic titanocene species from these starting materials was suggested to proceed through a formation of titanacyclobutane and the subsequent elimination of the halogen
Rapid access to highly functionalized alkylidene cyclohexanols through a one-pot desymmetrizing hydroformylation/carbonyl enecyclization starting from simple bisalkenylcarbinols is reported. Mechanistic insight into the carbonyl ene reaction is given, highlighting the importance of hyperconjugative substituent effects.
From a Remarkable Manifestation of Polar Effects in a Radical Fragmentation to the Convergent Synthesis of Highly Functionalized Ketones
作者:Laurent Debien、Samir Z. Zard
DOI:10.1021/ja400831w
日期:2013.3.13
A new radical addition/C-C bond fragmentation process is reported. Vinyl carbinols derived from 2-methyl-2-phenylpropanal react with radicals generated from xanthates to give the corresponding ketones. The radical cleavage reaction proceeds under mild conditions, in good to high yield, and in the presence of the unprotected carbinol. Highly functionalized 1,5-diketones and pyridines are readily available
Catalytic Asymmetric Synthesis of Secondary Nitriles via Stereoconvergent Negishi Arylations and Alkenylations of Racemic α-Bromonitriles
作者:Junwon Choi、Gregory C. Fu
DOI:10.1021/ja303442q
日期:2012.6.6
α-alkyl substituents; the first examples of the use of alkenylzinc reagents in stereoconvergent Negishi reactions of alkyl electrophiles; demonstration of the utility of a new family of ligands for asymmetric Negishi cross-couplings (a bidentate bis(oxazoline), rather than a tridentate pybox); in the case of arylzincreagents, carbon-carbon bond formation at a remarkably low temperature (-78 °C), the lowest