Synthesis of nitrodienes, nitrostyrenes, and nitrobiaryls through palladium-catalyzed couplings of β-nitrovinyl and o-nitroaryl thioethers
作者:Gardner S. Creech、Ohyun Kwon
DOI:10.1039/c3sc50773d
日期:——
A highly efficient, base-free, mild protocol for the palladium-catalyzed, copper-activated desulfitative couplings of vinyl and aryl β-nitrothioethers generates a wide variety of conjugated nitroorganics. Orthogonality to traditional SuzukiâMiyaura coupling is demonstrated, as well as synthetic utility, through reductive Cadogan cyclization, for the formation of indoles, carbazoles, and pyrroles.
Synthesis of Biaryls by Decarboxylative Hiyama Coupling
作者:Dmitry Katayev、Benjamin Exner、Lukas J. Gooßen
DOI:10.1002/cctc.201500068
日期:2015.7.13
A trimetallic palladium/copper/silver system has been developed that allows the decarboxylativeHiyamacoupling of ortho‐substituted aryl carboxylates with trialkoxyarylsilanes to give the corresponding biaryls. The cross‐coupling is catalyzed by a Pd/N‐heterocyclic carbene complex with silver carbonate aiding its reoxidation. Copper(II) fluoride acts as decarboxylation catalyst, stoichiometric oxidant
Pd-catalyzed arylation or benzylation of nitroazoles using aryl sulfonates or benzyl acetates is described. Electronically varied aryl tosylates and mesylates, as well as benzyl acetates, afford the arylated and benzylated products. Arylation of nitrobenzene is also reported. The relative rate for the arylation of halides is greater than that of tosylates using the reported reaction parameters. These studies enhance the scope of electrophiles for nitroarene arylations and benzylations, which was hitherto limited to the use of halide electrophiles.