Herein, we report a novel protocol for visible-light-driven alkylative carboxylation of alkenes with CO2 in the absence of external photocatalyst. Under the irradiation of visible light, a variety of 4-alkyl-1,4-dihydropyridines (alkyl-DHPs) serve as not only alkyl radical precursors but also photoexcited reductants probably with the potential to reduce benzyl radicals. Several styrenes and acrylates
在此,我们报告了一种在没有外部光催化剂的情况下用 CO 2对烯烃进行可见光驱动烷基化羧化的新方案。在可见光的照射下,各种 4-烷基-1,4-二氢吡啶(烷基-DHP)不仅可以作为烷基自由基的前体,而且还可以作为可能具有还原苄基自由基潜力的光激发还原剂。几种苯乙烯和丙烯酸酯适用于该反应,以良好至极好的产率得到结构多样的羧酸。这些反应具有温和的反应条件(1 个大气压的 CO 2、室温、可见光、无光催化剂和过渡金属)、良好的官能团耐受性、易扩展性以及高区域选择性和化学选择性。机理研究提供的证据表明,该反应可能涉及烷基自由基、苄基自由基和碳负离子,为 CO 2 的利用提供了一种新的策略。
BI-OAc-Accelerated C3–H Alkylation of Quinoxalin-2(1<i>H</i>)-ones under Visible-Light Irradiation
作者:Xiang-Kui He、Juan Lu、Ai-Jun Zhang、Qing-Qing Zhang、Guo-Yong Xu、Jun Xuan
DOI:10.1021/acs.orglett.0c02080
日期:2020.8.7
photoredox-catalyst-free radical alkylation of quinoxalin-2(1H)-ones has been described. This reaction utilizes 4-alkyl-1,4-dihydropyridines (R-DHPs) as alkyl radicalprecursors and acetoxybenziodoxole (BI-OAc) as an electron acceptor to undergo single-electron transfer with photoexcited R-DHPs. The benign conditions allow for good compatibility in the scope of both quinoxalin-2(1H)-ones and R-DHPs. The
Enantioselective Alkylamination of Unactivated Alkenes under Copper Catalysis
作者:Zibo Bai、Heng Zhang、Hao Wang、Hanrui Yu、Gong Chen、Gang He
DOI:10.1021/jacs.0c12333
日期:2021.1.20
An enantioselective addition reaction of various alkyl groups to unactivated internal alkenes under Cu catalysis has been developed. The reaction uses amide-linked aminoquinoline as the directing group, 4-alkyl Hantzsch esters as the donor of alkyl radicals, and rarely used biaryl diphosphine oxide as a chiral ligand. β-lactams featuring two contiguous stereocenters at Cβ and the β substituent can
Visible-light-promoted photocatalyst-free alkylation and acylation of benzothiazoles
作者:Pengxing Jiang、Li Liu、Jiajing Tan、Hongguang Du
DOI:10.1039/d1ob00734c
日期:——
Herein we report a protocol for the visible-light-mediated alkylation/acylation reaction of benzothiazoles. Alkyl/acyl substituted Hantzschesters are easily prepared and rationally used as radical precursors. In the presence of BF3·Et2O and Na2S2O8, various benzothiazole derivatives were readily obtained in good yields. Our user-friendly protocol can proceed by simple irradiation with blue LEDs (λ
在此,我们报告了苯并噻唑的可见光介导的烷基化/酰化反应的方案。烷基/酰基取代的Hantzsch酯易于制备,可以合理地用作自由基前体。在BF 3 ·Et 2 O和Na 2 S 2 O 8的存在下,容易以高收率获得各种苯并噻唑衍生物。我们的用户友好协议可以通过简单地用蓝色LED(λ = 465 nm)进行辐照来进行,而无需外部光催化剂的帮助。该反应的特征还在于温和的条件和可扩展性,因此为合成2-官能化的苯并噻唑提供了另一种有效的工具。
Visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones
作者:Fuyang Yue、Jianyang Dong、Yuxiu Liu、Qingmin Wang
DOI:10.1039/d1ob01806j
日期:——
Herein we report a mild, general protocol for visible-light-mediated alkylation of 4-alkyl-1,4-dihydropyridines with alkenyl sulfones. The protocol permits efficient functionalization of sulfones with a broad range of cyclic and acyclic secondary and tertiary alkyl groups and is scalable to the gram level. Its excellent functional group tolerance and mildness make it suitable for late-stage functionalization