The hydrodefluorination of CF3-substituted alkenes can be catalyzed by a nickel(II) hydride bearing a pincer ligand. The cata-lyst loading can be as low as 1 mol%. gem-Difluoroalkenes containing a number of functional groups can be formed in good to excellent yields, by a radical mechanism initiated by H• transfer from the nickel hydride. The relative reactivity of various substrates supports the proposed
CF3 取代烯烃的加氢脱氟可以由带有钳状配体的镍 (II) 氢化物催化。催化剂负载量可以低至 1 mol%。通过从氢化镍中转移 H• 引发的自由基机制,可以以良好到极好的产率形成含有许多官能团的 gem-二氟烯烃。各种底物的相对反应性支持所提出的机制,TEMPO 捕获实验也是如此。
Metal-free defluorinative arylation of trifluoromethyl alkenes <i>via</i> photoredox catalysis
作者:Rebecca J. Wiles、James P. Phelan、Gary A. Molander
DOI:10.1039/c9cc04265b
日期:——
photoredox-mediated processes are not amenable to aryl radical addition to trifluoromethyl alkenes. A metal-free, functional group-tolerant method for the preparation of benzylic gem-difluoroalkenes is described. Halogen atom abstraction from (hetero)aryl halides generates aryl radicals that undergo a defluorinative arylation of α-trifluoromethyl alkenes, tolerating electronically disparate aryl radicals and α-trifluoromethyl
Photoredox Generation of Carbon-Centered Radicals Enables the Construction of 1,1-Difluoroalkene Carbonyl Mimics
作者:Simon B. Lang、Rebecca J. Wiles、Christopher B. Kelly、Gary A. Molander
DOI:10.1002/anie.201709487
日期:2017.11.20
facile, scalable route to access functional‐group‐rich gem‐difluoroalkenes. Using visible‐light‐activated catalysts in conjunction with an arsenal of carbon‐radical precursors, an array of trifluoromethyl‐substituted alkenes undergoes radical defluorinative alkylation. Nonstabilized primary, secondary, and tertiary radicals can be used to install functional groups in a convergent manner, which would otherwise
作者:Yue Zhao、Claire Empel、Wenjing Liang、Rene M. Koenigs、Frederic W. Patureau
DOI:10.1021/acs.orglett.2c03419
日期:2022.12.9
The unprecedented photochemical late-stage defluorinative gem-difluoroallylation of arylsulfoniumsalts, which are formed site-selectively by direct C(sp2)─H functionalization, is herein disclosed. This method is distinguished by its mild reaction conditions, wide scope, and excellent site-selectivity. As showcase examples, a Flurbiprofen and Pyriproxyfen derivatives could be late stage C(sp2)─H
AbstractHere we report a general approach to make unnatural amino acids from readily available cysteine derivatives. This method capitalizes on an intramolecular radical substitution process that generates alkyl radicals through C−S cleavage. The resulting alkyl radicals partook in diverse C−C bond forming events. These reactions proceed under mild, photocatalytic conditions at room temperature, and