transition‐metal‐free carboarylation of alkynes with commercial and readily available alcohols as alkylating agents was realized in the presence of an environmentally benign calcium catalyst. Thereby, a novel protocol for the one‐step synthesis of highly congested, all‐carbon tetrasubstituted alkenes, as incorporated in potentially bioactive, complex dihydronaphthalene, chromene and dihydroquinoline
An Interrupted Pummerer/Nickel-Catalysed Cross-Coupling Sequence
作者:Miles H. Aukland、Fabien J. T. Talbot、José A. Fernández-Salas、Matthew Ball、Alexander P. Pulis、David J. Procter
DOI:10.1002/anie.201805396
日期:2018.7.26
An interrupted Pummerer/nickel‐catalysedcross‐coupling strategy has been developed and used in the elaboration of styrenes. The operationally simple method can be carried out as a one‐pot process, involves the direct formation of stable alkenyl sulfonium salt intermediates, utilises a commercially available sulfoxide, catalyst, and ligand, operates at ambient temperature, accommodates sp‐, sp2‐, and
Tamoxifen was synthesized using a nickel-catalyzed arylative carboxylation developed by our group. The key compound, tetrasubstituted alkene, was synthesized from disubstituted alkyne using a catalytic amount of Ni(0) and DBU in the presence of Ph 2 Zn under an atmosphere of carbondioxide. The reaction proceeded smoothly in a regio- and stereoselective manner, and the resultant tetrasubstituted alkene
Metal-Free Electrophilic Phosphination/Cyclization of Alkynes
作者:Yuto Unoh、Koji Hirano、Masahiro Miura
DOI:10.1021/jacs.7b02977
日期:2017.5.3
A metal-free electrophilicphosphination reaction has been developed. Electrophilic phosphorus species generated in situ from secondary phosphine oxides and Tf2O smoothly couple with alkynes possessing pendant nucleophiles to afford the corresponding phosphinated cyclization products in good yield. Preliminary NMR studies show that phosphirenium species may be involved as intermediates of the cyclization
and proton sponge in toluene, terminalalkynes were found to undergo the alkylation by alkyl triflates to provide unsymmetrical internal alkynes. This is the first example that a simple alkyl chain other than benzylic and norbornyl units can be introduced onto the alkynyl carbon atom under Lewis acid catalysis. Mechanisticstudies revealed that the activation of the alkyne by the zinc Lewis acid and proton