Mild Two-Step Process for the Transition-Metal-Free Synthesis of Carbon−Carbon Bonds from Allylic Alcohols/Ethers and Grignard Reagents
作者:Xinping Han、Yanhua Zhang、Jimmy Wu
DOI:10.1021/ja100747n
日期:2010.3.31
A mild two-step process for the regioselective, transition-metal-free preparation of carbon-carbon bonds from allylic alcohols/ethers and Grignardreagents is described. This process obviates the need for the harsh deprotection conditions usually required for removal of methyl ethers. The synthesis is accomplished by photochemically promoted allylic substitution reactions of allylic alcohols and ethers
The direct arylation of allylic sp3 C–H bonds via organic and photoredox catalysis
作者:James D. Cuthbertson、David W. C. MacMillan
DOI:10.1038/nature14255
日期:2015.3.5
particular, the direct arylation of non-functionalized allylic systems would enable access to a series of known pharmacophores (molecular features responsible for a drug’s action), though a general solution to this long-standing challenge remains elusive. Here we report the use of both photoredox and organic catalysis to accomplish a mild, broadly effective direct allylic C–H arylation. This C–C bond forming
未活化的 sp3 C-H 键的直接功能化仍然是合成有机化学家面临的最具挑战性的问题之一。这种转变的吸引力来自于它们通过简单和其他惰性结构单元的耦合促进复杂有机分子构建的能力,而不会引入无关的官能团。尽管最近做出了显着的努力,但事实证明,为 sp3 C-H 键参与 C-C 键形成反应建立一般和温和的策略是困难的。在此背景下,发现能够以催化方式直接使烯丙基甲基、亚甲基和次甲基碳官能化的化学转化是当务之急。尽管烯丙基 C-H 键的直接氧化和胺化方案(即,C-H 键,其中相邻的碳参与 C = C 键)已经广泛建立,烯丙基底物在 C-C 键形成反应中的参与迄今为止需要使用预官能化的偶联伙伴。特别是,非功能化烯丙基系统的直接芳基化将能够获得一系列已知的药效团(负责药物作用的分子特征),尽管解决这一长期挑战的通用解决方案仍然难以捉摸。在这里,我们报告了使用光氧化还原和有机催化来完成温和、广泛有效的直接烯丙基
Palladium-Catalyzed C–C Bond Formation of Arylhydrazines with Olefins via Carbon–Nitrogen Bond Cleavage
作者:Ming-Kui Zhu、Jun-Feng Zhao、Teck-Peng Loh
DOI:10.1021/ol202862t
日期:2011.12.2
The unactivated carbon–nitrogen bond of various aryl hydrazines was cleaved under very mild conditions by Pd(0) with the assistance of Pd(II). The in situ generated aryl palladium complex readily takes part in the C–C bond formation with olefins. This study offered a new mode of C–Pd bond formation, which will spur the development of palladium-catalyzed cross-coupling in the future.
Direct C(sp<sup>3</sup>)–H Arylation of Unprotected Benzyl Anilines and Alkylarenes by Organocatalysis under Visible Light
作者:Cheng Huang、Peng Xiao、Zhong-Ming Ye、Chen-Lu Wang、Chen Kang、Sheng Tang、Zhenhong Wei、Hu Cai
DOI:10.1021/acs.orglett.3c03980
日期:2024.1.12
alkylarenes via consecutive photoinduced electron transfer by visiblelight irradiation. Reductive quenching cycles and radical–radical cross-coupling were involved, and electron paramagnetic resonance experiments provide evidence for the formation of radical intermediates formed in situ. The protocol highlights transition metalfree, external oxidantfree, broad substrate scope, and high efficiency (>60 examples
Controlling Olefin Isomerization in the Heck Reaction with Neopentyl Phosphine Ligands
作者:Matthew G. Lauer、Mallory K. Thompson、Kevin H. Shaughnessy
DOI:10.1021/jo501840u
日期:2014.11.21
The use of neopentyl phosphine ligands was examined in the coupling of aryl bromides with alkenes. Di-tert-butylneopentylphosphine (DTBNpP) was found to promote Heck couplings with aryl bromides at ambient temperature. In the Heck coupling of cyclic alkenes, the degree of alkene isomerization was found to be controlled by the choice of ligand with DTBNpP promoting isomerization to a much greater extent than trineopentylphosphine (TNpP). Under optimal conditions, DTBNpP provides high selectivity for 2-aryl-2,3-dihydrofuran in the arylation of 2,3-dihydrofuran, whereas TNpP provided high selectivity for the isomeric 2-aryl-2,5-dihydrofuran. A similar complementary product selectivity is seen in the Heck coupling of cyclopentene. Heck coupling of 2-bromophenols or 2-bromoanilides with 2,3-dihydrofurans affords 2,5-epoxybenzoxepin and 2,5-epoxybenzazepins, respectively.