108643-81-8Relevant articles and documents
An alternative procedure for the O-trimethylsilylation of enolates generated by copper-catalyzed 1,4-additions
Andringa,Oosterveld,Brandsma
, p. 1393 - 1396 (1991)
Anhydrous lithium bromide has been successfully used as an additive instead of hexamethylphosphoric triamide in the O-trimethylsilation of enolates generated by copper halide-catalyzed reaction of Grignard reagents with a number of α,β-unsaturated carbony
Direct C-H α-Arylation of Enones with ArI(O2CR)2 Reagents
Sousa E Silva, Felipe Cesar,Van, Nguyen T.,Wengryniuk, Sarah E.
supporting information, p. 64 - 69 (2020/01/22)
α-Arylation of α,β-unsaturated ketones constitutes a powerful synthetic transformation. It is most commonly achieved via cross-coupling of α-haloenones, but this stepwise strategy requires prefunctionalized substrates and expensive catalysts. Direct enone C-H α-arylation would offer an atom- and step-economical alternative, but such reports are scarce. Herein we report the metal-free direct C-H arylation of enones mediated by hypervalent iodine reagents. The reaction proceeds via a reductive iodonium Claisen rearrangement of in situ-generated β-pyridinium silyl enol ethers. The aryl groups are derived from ArI(O2CCF3)2 reagents, which are readily accessed from the parent iodoarenes. The reaction is tolerant of a wide range of substitution patterns, and the incorporated arenes maintain the valuable iodine functional handle. Mechanistic investigations implicate arylation via an umpoled "enolonium" species and show that the presence of a β-pyridinium moiety is critical for the desired C-C bond formation.
Nickel-catalyzed reductive conjugate addition to enones via allylnickel intermediates
Shrestha, Ruja,Dorn, Stephanie C. M.,Weix, Daniel J.
, p. 751 - 762 (2013/03/14)
An alternative method to copper-catalyzed conjugate addition followed by enolate silylation for the synthesis of β-disubstituted silyl enol ether products (R1(R2)HCCH=C(OSiR43)R 3) is presented. This method uses haloarenes instead of nucleophilic aryl reagents. Nickel ligated to either neocuproine or bipyridine couples an α,β-unsaturated ketone or aldehyde (R2HC=CHC(O)R 3) with an organic halide (R1-X) in the presence of a trialkylchlorosilane reagent (Cl-SiR43). Reactions are assembled on the benchtop and tolerate a variety of functional groups (aldehyde, ketone, nitrile, sulfone, pentafluorosulfur, and N-aryltrifluoroacetamide), electron-rich iodoarenes, and electron-poor haloarenes. Mechanistic studies have confirmed the first example of a catalytic reductive conjugate addition of organic halides that proceeds via an allylnickel intermediate. Selectivity is attributed to (1) rapid, selective reaction of LNi0 with chlorotriethylsilane and enone in the presence of other organic electrophiles, and (2) minimization of enone dimerization by ligand steric effects.
The Kharasch reaction revisited: CuX3Li2-catalyzed conjugate addition reactions of Grignard reagents
Reetz, Manfred T.,Kindler, Alois
, p. C5 - C7 (2007/10/02)
The conjugate addition of Grignard reagents RMgX to α,β-unsaturated ketones and esters is effectively catalyzed by soluble copper ate-complexes of the type CuX3Li2, e.g.CuI*2LiCl.In the presence of Me3SiCl the corresponding ketone enolsilanes are formed in high yield and selectivity.Diastereoselectivity in the case of chiral ketones is similar to that observed by using stoichiometric amounts of cuprates R2CuLi.Thus CuX3Li2-catalyzed 1,4-additions of Grignard reagents may be an industrially viable process.Keywords: Copper; Magnesium; Lithium; Silicon; Ketone; Enolsilanes
Trimethylsilyl Chloride/Tetramethylethylenediamine Facilitated Additions of Organocopper Reagents (RCu) to Enones
Johnson, Carl R.,Marren, Thomas J.
, p. 27 - 30 (2007/10/02)
Alkylcoppers (RCu) add readily in a conjugate fashion to enones in the presence of TMSCl and TMEDA to give high yields of trimethylsilyl enol ethers.
