Visible-Light Photocatalytic Decarboxylation of α,β-Unsaturated Carboxylic Acids: Facile Access to Stereoselective Difluoromethylated Styrenes in Batch and Flow
development of synthetic methodologies which provide access to both stereoisomers of α,β-disubstituted olefins is a challenging undertaking. Herein, we describe the development of an operationallysimple and stereoselectivesynthesis of difluoromethylated styrenes via a visible-light photocatalytic decarboxylation strategy using fac-Ir(ppy)3 as the photocatalyst. Meta- and para-substituted cinnamic acids provide
induced three-component reaction of difluoroalkyl halides, unactivatedalkenes, and alkynyl sulfones is described, providing a direct and general approach to the construction of synthetically valuable β-difluoroalkylated alkynes under room temperature conditions. This represents the first intermolecular alkynyl-difluoroalkylation of unactivatedalkenes.
Copper-Mediated Direct Functionalization of Unsaturated C–C Bonds with Ethyl Bromo(difluoro)acetate: A Straightforward Access to Highly Valuable Difluoromethylated Alkenes
Abstract A copper-mediated fluorofunctionalization of alkenes and alkynes has been developed. This method provides ready access to trisubstituted difluoromethylated olefins (from dihydropyrans, glycal derivatives, or terminal alkynes) or to tetrasubstituted olefins (from disubstituted alkynes). The products were obtained in good to high yields with acceptable E/Z selectivities. Finally, a first direct
Synthesis of fluoroalkylated alkynes <i>via</i> visible-light photocatalysis
作者:Naila Iqbal、Naeem Iqbal、Sung Su Han、Eun Jin Cho
DOI:10.1039/c8ob02486c
日期:——
Fluoroalkylated alkynes, which are versatile building blocks for the synthesis of various biologically active organofluorine compounds, were synthesized from easily available alkynyl halides and fluoroalkyl halides by visible-light photocatalysis. Addition of fluoroalkyl radicals to alkynes and subsequent dehalogenation selectively yielded fluoroalkylated alkynes.
Stoichiometric and catalytic intermolecularPauson−Khandreactions (PKRs) of dissymmetric fluorinated alkynes were performed, affording regioselectively α-fluorinated cyclopentenones. Ethyl 4,4,4-trifluorobutynoate was an excellent substrate; its reaction with norbornadiene gave the corresponding PKR adduct in good yield and complete regioselectivity. Conjugate addition of nitroalkanes or cyanide to