Palladaphosphacyclobutenes as catalysts in Heck and Suzuki reactions

Abstract

Heck reactions of aryl halides with various olefins and Suzuki reactions of aryl halides with phenylboronic acid catalyzed by palladaphosphacyclobutene have been investigated. The scope of the Heck reaction has been investigated in N,Ndimethylacetamide at 140• C using NaOAc as base. Using 0.1% molar ratio of palladaphosphacyclobuyenes, aryl bromides were converted into 1,2-substitutedethene products in good to high yields through coupling with both vinylarenes and acrylates. Actived aryl chloride reacted with styrene to afford 1,2-substitutedethene products in moderate yields. The scope of the Suzuki reaction has been conducted in toluene at 110• C using Cs 2 CO 3 as base. Using 0.1% molar ratio of palladaphosphacyclobutene, aryl bromides reacted with phenylboronic acid to afford diaryl derivatives in excellent yield.

Highly bulky and stable geometry-constrained iminopyridines: Synthesis, structure and application in Pd-catalyzed Suzuki coupling of aryl chlorides

“…Typical ligands that successfully enhanced the reactivity of palladium species towards the oxidative addition of aryl or alkyl halides include phosphine ligands independently developed by, for example, Buchwald [ 13 – 15 ], Hartwig [ 16 – 17 ], Fu [ 18 – 20 ], Kwong [ 21 – 23 ], Tang [ 24 – 27 ] and Lundgren [ 28 ], and N-heterocyclic carbene ligands due to the inherent strong sigma-donating property [ 29 ]. Alternatively, the palladacycles reported by Herrmann and Beller in the 1990s [ 30 ] effectively elongated the lifetime of the active Pd species through employing bidentate or multidentate ligands [ 31 – 36 ]. Meanwhile nitrogen ligands are also widely used for palladium catalysts in coupling reactions with the advantage of convenient synthetic methods, easy functional group modifications and better stability [ 37 – 43 ].…”

A Highly Efficient Ruthenium(II) Catalyst with (1,2-Diarylvinyl)phosphine Ligands for Direct Ortho Arylation of 2-Arylpyridine with Aryl Chlorides

“…For many years, we have been engaged in the study of zirconophosphination of alkynes . We disclosed a versatile and general method for the preparation of various alkenylphosphines, which have been widely employed in organic synthesis . Herein, we would like to report the synthesis and characterization of ruthenium complexes with (1,2-diarylalkenyl)phosphine and their catalytic activity in the arylation of 2-arylpyridine with aryl chlorides via C−H bond activation, although phosphine ligand free ruthenium complexes have been employed for direct arylations with aryl chlorides. , …”

Reactivity of [(2-Phosphino)ethenyl]zirconocene Chloride toward CpM(CO)3Cl (M = Mo, W): Formation of [(3-Phosphino)propenoyl]dicarbonyl(cyclopentadienyl)metal, {CpM(CO)2[(CO)CR═CRPPh2]}

“…In these reactions, transmetalation of Zr−C to Cu−C was necessary . Recently, we reported reaction of [(2-phosphino)ethenyl]zirconocene chlorides with Pd(CH 3 CN) 2 Cl 2 to give dimeric [(2-phosphino)ethenyl]palladium chlorides, which are useful catalysts in coupling reactions . Moreover, the [(2-phosphino)ethenyl]zirconocene chlorides showed high activities for ethylene polymerization as well as copolymerization of ethylene with α-olefin or norbornene in the presence of methylaluminoxane (MAO) as cocatalyst .…”