Ni-catalysed, domino synthesis of tertiary alcohols from secondary alcohols

The use of in situ generated (NHC)-Ni catalytic species (NHC = N-heterocyclic carbene) allows for the synthesis, in short reaction times, of a variety of tertiary alcohols from secondary alcohols through a domino oxidation-addition protocol

A General Method for the Suzuki−Miyaura Cross-Coupling of Sterically Hindered Aryl Chlorides: Synthesis of Di- and Tri-ortho-substituted Biaryls in 2-Propanol at Room Temperature

The catalytic formation of di- and trisubstituted ortho biaryl junctions has been achieved using a palladacylce pre-catalyst bearing a N-heterocyclic carbene ligand. This transformation is performed at room temperature in technical grade 2-propanol

Transition metal catalyzed element–element' additions to alkynes

The efficient and stereoselective synthesis of, or precursors to, multi-substituted alkenes has attracted substantial interest due to their existence in various industrially and biologically important compounds. One of the most atom economical routes to such alkenes is the transition metal catalyzed hetero element–element' p-insertion into alkynes. This article provides a thorough up-to-date review on this area of chemistry, including discussions on the mechanism, range of Esingle bondE' bonds accessible and the stoichiometric/catalytic transition metal mediators employed

(N-Heterocyclic Carbene)₂‑Pd(0)-Catalyzed Silaboration of Internal and Terminal Alkynes: Scope and Mechanistic Studies

Pd­(ITMe)₂(PhCCPh) acts as a highly reactive precatalyst in the silaboration of terminal and internal alkynes to yield a number of known and novel 1-silyl-2-boryl alkenes. Unprecedented mild reaction temperatures for terminal alkynes, short reaction times, and low catalytic loadings are reported. During mechanistic studies, <i>cis</i>-Pd­(ITMe)₂(SiMe₂Ph)­(Bpin) was directly synthesized by oxidative addition of PhMe₂SiBpin to Pd­(ITMe)₂(PhCCPh). This represents a very rare example of a (silyl)­(boryl)palladium complex. A plausible catalyst decomposition route was also examined

(N-Heterocyclic Carbene)-Pd-Catalyzed Anaerobic Oxidation of Secondary Alcohols and Domino Oxidation−Arylation Reactions

The use of commercially available (SIPr)Pd(cinnamyl)Cl (SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene) as a precatalyst for the anaerobic oxidation of secondary alcohols is described. The use of this complex allows for a drastic reduction in the reaction times and catalyst loading when compared to the unsaturated counterpart. This catalytic system is compatible with the use of microwave dielectric heating, decreasing even further catalyst loading and reaction times. Domino Pd-catalyzed oxidation−arylation reactions of secondary alcohols are also presented

Synthesis of trans-mono(silyl)palladium(II) bromide complexes

The stoichiometric reaction of cis-[Pd(ITMe)2(SiR3)2], where (SiR3 = SiMe3 and SiMe2Ph and ITMe = 1,3,4,5-tetramethylimidazol-2-ylidene) with allyl bromide affords the corresponding allylsilanes along with complexes of the type trans-[Pd(ITMe)2(SiR3)(Br)]. The structure of trans-[Pd(ITMe)2(SiMe2Ph)Br] 2b has been determined in the solid state and displays a slightly distorted square-planar geometry with the two N-heterocyclic carbene ligands in a trans-configuration

Sonogashira Couplings Catalyzed by Collaborative (<i>N</i>‑Heterocyclic Carbene)-Copper and -Palladium Complexes

A general protocol for the Sonogashira reaction using a 100:1 combination of (<i>N</i>-heterocyclic carbene)-Cu and (<i>N</i>-heterocyclic carbene)-Pd complexes is presented. Catalyst loadings of 1 mol % (NHC)-Cu and 0.01 mol % (NHC)-Pd allow for the coupling of aryl bromides and aryl alkynes, in air and in a non-anhydrous solvent, in high yields

Homogeneous, Anaerobic (N-Heterocyclic Carbene)−Pd or −Ni Catalyzed Oxidation of Secondary Alcohols at Mild Temperatures

The use of aryl chlorides as oxidants for the selective oxidation of a variety of secondary alcohols in anaerobic conditions with (NHC)−Pd and −Ni systems (NHC = N-heterocyclic carbene) at very mild temperatures is presented

Synthesis of trans-mono(silyl)palladium(II) bromide complexes

The stoichiometric reaction of cis-[Pd(ITMe)2(SiR3)2], where (SiR3 = SiMe3 and SiMe2Ph and ITMe = 1,3,4,5-tetramethylimidazol-2-ylidene) with allyl bromide affords the corresponding allylsilanes along with complexes of the type trans-[Pd(ITMe)2(SiR3)(Br)]. The structure of trans-[Pd(ITMe)2(SiMe2Ph)Br] 2b has been determined in the solid state and displays a slightly distorted square-planar geometry with the two N-heterocyclic carbene ligands in a trans-configuration

A Comparative Study on (NHC)Pd(acac)Cl Complexes (NHC = N-heterocyclic carbene): Indications for the Origin of the Different Reactivity of Saturated and Unsaturated NHC in Cross-Coupling Reactions

The synthesis of the new well-defined and air-stable complex (SIPr)Pd(acac)Cl (SIPr = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) is described, and the catalytic activity of this new complex has been tested in the α-arylation of ketones and in Buchwald−Hartwig amination reactions. The significant differences in catalytic performance when compared to the previously reported, unsaturated counterpart (IPr)Pd(acac)Cl (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) are discussed by means of X-ray crystallography and on the basis of their varying solution dynamics, observed by 1H NMR spectroscopy