A-arylation of carbonyl

Serendipity before design in the a-arylation of carbonyl compounds. 

The a-arylation of carbonyl compounds (sometimes in enantioselective version) such as ketones,107-115 amides,114 115 lactones,116 azlactones,117 malonates,118 piperidinones,119,120 cyanoesters,121,122 nitriles,125,124 sul-fones, trimethylsilyl enolates, nitroalkanes, esters, amino acids, or acids has been reported using palladium catalysis. The asymmetric vinylation of ketone enolates has been developed with palladium complexes bearing electron-rich chiral monodentate ligands.155... 

A. Culkin, J. F. Hartwig, Palladium-Catalyzed a-Arylation of Carbonyl Compounds and Nitriles, Acc. Chem. Res. 2003, 36, 234-245. 

Palladium-catalyzed a-arylation of carbonyl derivatives and its applications in the synthesis of natural products 05CJO282. 

A variety of bases have been used in the palladium-catalyzed a-arylation of carbonyl derivatives. The pKa of the carbonyl moiety determines the choice of the base. The preferred bases for the a-arylation with ester derivatives are either NaHMDS (r-butyl propionate) or LiHMDS (f-butyl acetate) as KHMDS was reported to lead to lower yield because of competing hydrodehalo-genation. More sensitive substrates such as a-imino esters, malonates, or cyanoesters required the use of a milder base, as decomposition was observed with HMDS bases. 

Reaction of diphenylsulfoxide with triflic anhydride affords, as precedently mentioned, the corresponding sulfoxonium triflate, a powerful reagent for numerous reactions, such as a-arylation of carbonyls, enolate additions,or nucleophilic substitution on alkenes (102). ... 

Inter-Intra Tandem Processes Involving Pd-Catalyzed a-Arylation of Carbonyl Compounds with 1,2-Dibromoarenes. 1,2-Dibromoarenes have been shown to undergo Pd-catalyzed inter-intra tandem processes leading to the formation of cyclic compounds, as summarized in Scheme 28. In some examples, however, the cyclization process itself does not actually involve Pd-catalyzed a-arylation. It instead involves either an interesting diaryl ether formation (Sect, in.3.3) or intramolecular Heck reaction (Sect. IV.2.2). 

Reviews have covered accounts of palladium-catalysed a-arylation of carbonyl-type compounds over the past 5 years, including enantioselective cases ° and enantioselective arylation and alkenylation of carbonyl and imino groups. ... 

Palladium-CatalYzed a-Arylation of Carbonyl Compounds and Nitriles I J5... 

In 1998, Buchwald and coworkers reported the first example of the direct catalytic asymmetric a-arylation of ketone enolates using (S)-BINAP/Pd2(dba)3 as the catalyst [54]. Since then, the transition-metal-catalyzed enantioselective a-arylation of carbonyl compoimds has emerged as a simple and robust method for the construction of chiral benzylic quaternary centers [55]. 

Over the last few years, great advances have been made on the a-arylation of carbonyl compounds catalyzed by transition-metal catalysts. A large number of carbonyl compounds, such as ketones, aldehydes, esters, and amides, can be coupled with electron-neutral, electron-rich, electron-poor. 

Sacks. C. E. Fuchs, P. L. a-Arylation of Carbonyl Groups. Utilization of the -Toluenesulfonylazo Olefin Functional Group as an Enolonium Synthon J. Am. Chem. Soc. 1975, 97, 7273-727A See also Stork, G. Ponaras, A. A. or-Alkylation and Arylation of or,)3-Unsaturated Ketones /. Org. Chem. 1976, 41, 2937-2939. 

Organocatalysis in combination with oxidants enables intramolecular asymmetric a-arylation of carbonyl compounds. In 2009, Nicolaou and MacMillan independently reported asymmetric a-arylation of aldehydes (Scheme 7.15). Using MacMillan s imidazoline catalyst and an appropriate... 

Mono-a-arylation of carbonyl compounds with aryl halides in dioxane has been effected using the [Pd(cinnamyl)Cl]2/DalPhos catalyst system. 1-Methylimidazole exhibits unusually high efficiency as a base catalyst for conversion of ArCOCH3 to tra 5 -ArCOCH=CHNMe2 on reaction with DMF-DMA this has been ascribed to supramolecular domino catalysis. An unusual a-carboxylative y-lactonization of (g) y-alkynyl ketones (50) on reaction with CO2 has been catalysed by AgOBz with a triazabicyclo decene (Scheme 38). ... 

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