5012-90-8Relevant articles and documents
Palladium-NHC (NHC = N-heterocyclic Carbene)-Catalyzed Suzuki-Miyaura Cross-Coupling of Alkyl Amides
Wang, Chang-An,Rahman, Md. Mahbubur,Bisz, Elwira,Dziuk, B?az?ej,Szostak, Roman,Szostak, Michal
, p. 2426 - 2433 (2022/02/17)
We report the Pd-catalyzed Suzuki-Miyaura cross-coupling of aliphatic amides. Although tremendous advances have been made in the cross-coupling of aromatic amides, C-C bond formation from aliphatic amides by selective N-C(O) cleavage has remained a major challenge. This longstanding problem in Pd catalysis has been addressed herein by a combination of (1) the discovery of N,N-pym/Boc amides as a class of readily accessible amide-based reagents for cross-coupling and (2) steric tuning of well-defined Pd(II)-NHC catalysts for cross-coupling. The methodology is effective for the cross-coupling of an array of 3°, 2°, and 1° aliphatic amide derivatives. The catalyst system is user-friendly, since the catalysts are readily available and are air- and bench-stable. Mechanistic studies strongly support an amide bond twist and external nN → π*C═O/Ar delocalization as a unified enabling feature of N,N-pym/Boc amides in selective N-C(O) bond activation. The method provides a rare example of Pd-NHC-catalyzed cross-coupling of aliphatic acyl amide electrophiles.
Cu(I) mediated hydrogen borrowing strategy for the α-alkylation of aryl ketones with aryl alcohols
Lawal, Nasir S.,Ibrahim, Halliru,Bala, Muhammad D.
, p. 275 - 285 (2021/02/09)
Abstract: New triazolium Schiff bases (TSBs) were synthesised via a simple and high throughput process. The new salts were successfully characterised. When reacted with Cu(CH3CN)4PF6, the TSB salts formed mononuclear triazole Schiff base copper(I) complexes and dinuclear complexes that were also characterised. The?copper complexes were generated in situ (mixtures of TSB salts with Cu(CH3CN)4PF6) and applied as homogeneous catalysts for the C–C coupling of a variety of aryl ketones with aryl alcohols, from which?significant reactivity was observed. Reaction conditions were optimised, and the results indicate that the catalyst systems are very robust. A catalyst concentration of 10?mol% efficiently and selectively catalysed the α-alkylation of methyl phenyl ketone and its derivatives to afford up to 94% yield of 1,3-diphenylpropan-1-one and its analogues. The process is adaptable with analogues of acetophenone and benzyl alcohol bearing various regulating substituents tolerated. Graphic abstract: [Figure not available: see fulltext.].
Unveiling the catalytic nature of palladium-N-heterocyclic carbene catalysts in the α-alkylation of ketones with primary alcohols
?etinkaya, Bekir,Ero?lu, Zafer,Gülcemal, Süleyman,Metin, ?nder,Ovezova, Mamajan
supporting information, p. 10896 - 10908 (2021/08/17)
We report herein the synthesis of four new Pd-PEPPSI complexes with backbone-modified N-heterocyclic carbene (NHC) ligands and their application as catalysts in the α-alkylation of ketones with primary alcohols using a borrowing hydrogen process and tandem Suzuki-Miyaura coupling/α-alkylation reactions. Among the synthesized Pd-PEPPSI complexes, complex2chaving 4-methoxyphenyl groups at the 4,5-positions and 4-methoxybenzyl substituents on the N-atoms of imidazole exhibited the highest catalytic activity in the α-alkylation of ketones with primary alcohols (18 examples) with yields reaching up to 95%. Additionally, complex2cwas demonstrated to be an effective catalyst for the tandem Suzuki-Miyaura-coupling/α-alkylation of ketones to give biaryl ketones with high yields. The heterogeneous nature of the present catalytic system was verified by mercury poisoning and hot filtration experiments. Moreover, the formation of NHC-stabilized Pd(0) nanoparticles during the α-alkylation reactions was identified by advanced analytical techniques.
