Photoinduced direct 4-pyridination of C(sp3)–H Bonds
作者:Tamaki Hoshikawa、Masayuki Inoue
DOI:10.1039/c3sc51080h
日期:——
Direct substitution of hydrogen in C(sp3)âH bonds by 4-pyridine was achieved by employing benzophenone and 4-cyanopyridine in aqueous acetonitrile under photo-irradiating conditions. This simple and mild 4-pyridination proceeds in a highly chemoselective manner especially at benzylic C(sp3)âH bonds without affecting polar functional groups, and enables intermolecular formation of sterically hindered bonds between alkylaromatics and 4-pyridine. The present methodology thus serves as a powerful tool for construction of biologically active and functional molecules with 4-pyridine substructures.
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
Photochemical Organocatalytic Functionalization of Pyridines via Pyridinyl Radicals
作者:Emilien Le Saux、Eleni Georgiou、Igor A. Dmitriev、Will C. Hartley、Paolo Melchiorre
DOI:10.1021/jacs.2c12466
日期:2023.1.11
We report a photochemical method for the functionalization of pyridines with radicals derived from allylic C–H bonds. Overall, two substrates undergo C–H functionalization to form a new C(sp2)–C(sp3) bond. The chemistry harnesses the unique reactivity of pyridinyl radicals, generated upon single-electron reduction of pyridinium ions, which undergo effective coupling with allylic radicals. This novel