The use of methyl 2,2-difluoro-2-(fluorosulfonyl)acetate as the difluorocarbene source to generate an in situ source of difluoromethylene triphenylphosphonium ylide
摘要:
Under moderate conditions in the presence of a demethylating reagent, such as iodide, methyl 2,2,-difluoro-2-(fluorosulfonyl)acetate (MDFA) releases difluorocarbene, which in the presence of triphenylphosphine forms difluoromethylene triphenylphosphonium ylide. When the process is carried out also in the presence of aldehydes or activated ketones, the ensuing in situ Wittig-type reaction of the ylide with the carbonyl reactants produces 1,1-difluoroalkenes in good yield. Density Functional Theory calculations were used to provide new estimates of the energies and structures of singlet and triplet states of CH2:, CHF:, and CF2: carbenes, as well as those of their respective triphenylphosphonium ylides. (C) 2013 Elsevier B.V. All rights reserved.
Visible light photocatalytic decarboxylative monofluoroalkenylation of α-amino acids with gem-difluoroalkenes
作者:Jingjing Li、Quentin Lefebvre、Haijun Yang、Yufen Zhao、Hua Fu
DOI:10.1039/c7cc05758j
日期:——
A novel, efficient and general visible-light photocatalytic decarboxylative monofluoroalkenylation of N-protected α-amino acids with gem-difluoroalkenes is reported, affording the corresponding α-amino monofluoroalkenes.
Cobalt-Catalyzed Selective Unsymmetrical Dioxidation of <i>gem</i>-Difluoroalkenes
作者:Douglas L. Orsi、Justin T. Douglas、Jacob P. Sorrentino、Ryan A. Altman
DOI:10.1021/acs.joc.0c00415
日期:2020.8.21
proceed through reactive intermediates prone to eliminate a fluorine atom and generate monofluorinated products. Taking advantage of the distinct reactivity of gem-difluoroalkenes, we present a cobalt-catalyzed regioselective unsymmetrical dioxygenation of gem-difluoroalkenes using phenols and molecular oxygen, which retains both fluorine atoms and provides β-phenoxy-β,β-difluorobenzyl alcohols. Mechanistic
Base Catalysis Enables Access to α,α-Difluoroalkylthioethers
作者:Douglas L. Orsi、Brandon J. Easley、Ashley M. Lick、Ryan A. Altman
DOI:10.1021/acs.orglett.7b00386
日期:2017.4.7
A nucleophilicaddition reaction of aryl thiols to readily available β,β-difluorostyrenes provides α,α-difluoroalkylthioethers. The reaction proceeds through an unstable anionic intermediate, prone to eliminate fluoride and generate α-fluorovinylthioethers. However, the use of base catalysis overcomes the facile β-fluoride elimination, generating α,α-difluoroalkylthioethers in excellent yields and
which otherwise are essentially reluctant towards F‐nucleoplilic addition, now readily participate in this fluoroallylation reaction. Furthermore, this strategy provides an elegant example for the generation, as well as functionalization, of α‐CF3‐substituted benzylic radical intermediates using cheap and readily available starting materials.
Synthesis of Alkylated Monofluoroalkenes via Fe-Catalyzed Defluorinative Cross-Coupling of Donor Alkenes with <i>gem</i>-Difluoroalkenes
作者:Ling Yang、Wei-Wei Ji、E Lin、Ji-Lin Li、Wen-Xin Fan、Qingjiang Li、Honggen Wang
DOI:10.1021/acs.orglett.8b00471
日期:2018.4.6
A reductive cross-coupling of gem-difluoroalkenes with diverse unactivated and heteroatom substituted olefins through a Fe-catalyzed hydrogen atom transfer (HAT) strategy is reported. Different from the previous HAT-type olefin cross-coupling reactions, the presence of a fluorineatom in the molecule results in a stereoselective β-F cleavage, leading to a C(sp2)–C(sp3) bond formation. A wide variety