Saturated N-Heterocyclic CarbeneOxime and Amine Palladacycle Catalysis of the Mizoroki-Heckand the Suzuki Reactions

Abstract

ortho-Palladated aryl oxime and amines with a N-heterocyclic carbene ligand show increased thermal stability and catalyze the Mizoroki-Heck and Suzuki reaction with high yields, and moderate TON (2,000-92,000) and TOF (200-4,300 h -1 ). Homo coupling of the aryl halides gave low yields of the biaryls in the presence of these catalysts.

Palladacycles in catalysis – a critical survey

“…Such complexes were used for Heck reaction between bromoarenes and acrylate or styrene (0.0016 mol% Pd, K 2 CO 3 , TBABr, NMP, 130-150°C) giving high yields with both activated and deactivated substrates, and TONs of 10 4 order of magnitude. The same system with higher catalyst loading (0.01 mol% Pd) can be applied to activated aryl chlorides giving Heck products in good yields and TONs of 10 3 order of magnitude [125]. Oxime 58 and benzylamine 59 palladacycles (Fig.…”

“…In several cases comparative runs with hybrid complexes of oxime palladacycle with PPh 3 and P(OEt) 3 gave similar results (variations of yields in the range 65.7-93.2% in one example and 73.2-92.6 in the other example). Hybrid palladacycle-carbene complexes 58, 59 were also tested in the reaction of aryl halides (iodides, bromides, activated chlorides) with PhB(OH) 2 (0.01-0.1 mol% Pd, K 3 PO 4 , DMF, 120°C) to give modest to good yields [125].…”

ChemInform Abstract: Oxime‐Derived Palladacycles: Applications in Catalysis

“…[22] Saturated N-heterocyclic carbene (NHC) oxime palladacycle 5,p repared by reactiono fc omplexes 1 with the saturated NHC under m-xylene at reflux, showedi ncreasingt hermals tabilityb ut similare fficiencies. [23][24][25] Beletskaya et al described the use of differentN C-palladacycles including oxime derivative 1a in MH reactions of iodobenzene with styrene and ethyl acrylate in N,N-dimethylacetamide (DMAc) at 85 8C. [26] The arylationo fe lectron-rich styrenes such as 4-methoxy and 2,4-, 3,4-, and 3,5-dimethoxystyrenes and4vinylpyridine has been performed with 4-hydroxyacetophenone palladacycle 1e anda pplied to the synthesis of methoxylated stilbenes, [27] namely,s tilbenoids derived from 3,5-dimethoxyiodobenzene, which have shown potent CYP1B1 inhibitory activity valuable for the development of chemo preventive or therapeutic cancer agents.…”

Synthesis, X-ray structures, and catalytic activities of (κ2-C,N)-palladacycles bearing imidazol-2-ylidenes

“…Apparently palladacyclic catalysts alone are helpless and the modulation of activity of Pd catalyst by the co-ligands is required, e.g. in the case of unactivated aryl chlorides, as well as the reactions of aryl bromides at lower temperatures [5][6][7][8][9][10]. An interesting approach is to combine palladacycles as convenient Pd sources and special ligands in catalytic system, e.g.…”