A systematic study of benzyl cation initiated cyclization reactions
摘要:
A systematic investigation of benzyl cation initiated cyclization reactions to form six-membered carbocycles is presented. The generation of benzyl cations from benzylic bromides, ethers, and alcohols followed by intramolecular capture provided good yields of cyclized products by use of several different cyclization terminators (e.g., phenyl, alkene, beta-keto ester). A study on the effect of changing the electronic nature of substituents para to the benzyl cation showed that even electron-withdrawing substituents such as quaternary ammonium afford high yields of cyclization products. The formation of five- and seven-membered carbocycles was briefly investigated and found to be less general than the formation of the corresponding six-membered carbocycles.
Herein we report a novel visible-light-mediated external reductant-free reductive cross coupling for the construction of C sp2–C sp3 bonds. A variety of benzylammonium salts underwent selective coupling with (hetero)aryl nitriles to deliver important diarylmethanes undermild reaction conditions. Importantly, photocatalysts can be omitted for many cases, which might involve the electron donor acceptor
Switchable Direct Oxygenative Arylation of C(sp<sup>3</sup>)–H Bonds via Electrophotocatalysis
作者:Yan Zhang、Xiang Sun、Ji-Hu Su、Tong Li、Chengbin Du、Kuiliang Li、Qi Sun、Zhenggen Zha、Zhiyong Wang
DOI:10.1021/acs.orglett.3c01751
日期:2023.7.14
A metal-free electrophotochemical C(sp3)-H arylation was developed under mild conditions. This method enables a switchable synthesis of diaryl alcohols and diaryl alkanes from inactive benzylic carbons. More importantly, a cheap and safe mediator N-chlorosuccinimide (NCS) was developed, which was employed for the hydrogen atom transfer (HAT) process of the benzylic C–H bond. In addition, this active
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
Benzylic C–H arylation with dicyanoarenes<i>via</i>convergent paired electrolysis
作者:Shanyu Tang、Guillaume Vincent
DOI:10.1039/d3gc00866e
日期:——
methylarene derivatives and 1,4-dicyanoarenes to perform the arylative functionalization of a benzylic C(sp3)–H bond to form 1,1-biarylmethane derivatives that are found in several drugs and biologically active compounds. This electrochemical process proceeds via the coupling of a benzylic radical or a benzylic carbocation with a 1,4-dicyanoarene radical anion to form the desired C–C bond followed by
Electrochemical deoxygenative arylation of aldehydes and ketones
作者:Meng Li、Yue Tian、Kunhui Sun、Zhimin Xu、Lifang Tian、Yahui Wang
DOI:10.1039/d3cc01395b
日期:——
of trivalent phosphine under electrochemical conditions. Reductive coupling between electron-deficient arenes and the carbonyl groups of aldehydes or ketones occurs at the cathode to yield diaryl alcohols. At the anode, the trivalent phosphine reagent may undergo single-electron oxidation to generate its radical cation, which reacts with the diaryl alcohols to form dehydroxylated products.