Solvent-free oxidation of alcohols by t-butyl hydroperoxide catalyzed by water-soluble copper complex

The catalytic system composed of CuCl₂ and 2,2′-biquinoline-4,4′-dicarboxylic acid dipotassium salt (BQC), was found to be highly efficient for the selective oxidation of secondary benzylic, allylic and propargylic alcohols to the corresponding ketones, with aqueous t-butyl hydroperoxide under phase-transfer catalysis conditions. The catalytic system is stable and can be recycled and reused several times without loss of activity.     

Synthesis of ferrocenyl-β-enamino ketones: A search of ferrocenylpyrido[2,3-d]pyrimidines using a Ni(CN)2/NaOH/KCN system as catalytic precursor

New ferrocenyl-β-enamino ketones (1-6), were obtained from 6-amino-1,3-dimethyluracil and several ferrocenyl-α-ketoalkynes via MeNH⁻ anion in a monophasic aqueous system containing Ni(CN)₂/CO/NaOH/H₂O/KCN are described. A mechanism for obtaining of β-enamino ketones is suggested.     

Palladium-catalyzed asymmetric hydrogenation of simple ketones activated by Brønsted acids

Homogeneous Pd(OCOCF₃)₂/(R)-C₄-TunePhos has been successfully applied in the asymmetric hydrogenation of simple ketones activated by catalytic amount of Brønsted acid with up to 88% ee.     

Chitosan-SO3H: an efficient,biodegradable, and recyclable solid acid for the synthesis of quinoline derivatives via Friedländer annulation

Chitosan-SO₃H is found to catalyze the Friedländer condensation/annulation reaction of 2-aminoaryl ketones with α-methyleneketones to produce the corresponding quinoline derivatives in high yields in short reaction times. The use of recyclable and biodegradable chitosan-SO₃H makes this method quite simple, more convenient, and economically viable compared to acid catalyzed methods reported in the literature.     

Highly stereoselective synthesis of trans-4-trifluoromethylsulfonyl-2,3-dihydrofurans from arsonium ylides and (E)-α-trifluoromethylsulfonyl-α,β-unsaturated ketones

The reactions of arsonium bromides with (E)-α-trifluoromethylsulfonyl-α,β-unsaturated ketones in the presence of Cs₂CO₃ or K₂CO₃ proceeded smoothly under refluxing condition in dichloromethane (DCM) to give the corresponding trifluoromethylated trans-2,3-dihydrofurans in good to excellent yields with high stereoselectivity.     

Z/E Stereoselective synthesis of β-bromo Baylis-Hillman ketones using MgBr2 as promoter via a one-pot three-component reaction

The first time steroselective synthesis of (Z)-β-bromo Baylis-Hillman ketones has been achieved using a one-pot three-component reaction. The new system uses MgBr₂ as both the Lewis acidic promoter and the bromine source for the Michael-type addition with α,β-acetylenic ketones to form an active β-bromo allenolate intermediate, which in turn attacks various aldehydes to afford β-bromo Baylis-Hillman adducts in good yields and Z-selectivity.     

Facile synthesis of α,β-acetylenic ketones and 2,5-disubstituted furans: consecutive activation of triple and double bond with ZnBr2 toward the synthesis of furan ring

α,β-Acetylenic ketones were synthesized from the reaction of acid chlorides and acetylenic compounds in the presence of ZnBr₂ and DIEA in acetonitrile. From the acetylenic ketones having nearby methylene unit, 2,5-disubstituted furan derivatives could be synthesized under the same reaction conditions.     

Highly efficient synthesis of aryl ketones by PEPPSI-palladium catalyzed acylative Suzuki coupling of amides with diarylborinic acids

An improved acylative cross-coupling of various N-methyl-N-tosyl amides with diarylborinic acids for synthesis of aryl ketones is developed. In most cases, aryl ketones could be obtained in excellent yields by using 1?mol% 2,6-diisopropylphenylimidazolylidene and 3-chloropyridine co-supported palladium chloride as catalyst in the presence of 3 equiv. K₂CO₃ as base in refluxing THF. The readily prepared and cost-effective substrates, N-methyl-N-tosylamides and diarylborinic acids, and the commercially available catalyst system promise a practical and efficient access to aryl ketones.     

Tandem enantioselective conjugate addition-Mannich reactions: efficient multicomponent assembly of dialkylzincs, cyclic enones and chiral N-sulfinimines

A convenient access to enantiopure β-amino ketones through a multicomponent reaction of dialkyl zinc reagents, cyclic enones and chiral N-tert-butanesulfinimines is disclosed. Four diastereoisomers can be selectively obtained by the appropriate choice of the chiral ligand (L or ent-L) and the chiral N-sulfinimine (R_S or S_S). The protocol is particularly efficient when enolisable N-sulfinimines are used.     

An efficient synthesis of (E)-α,β-unsaturated ketones and esters with total stereoselectivity by using chromium dichloride

(E)-α,β-Unsaturated ketones 1 or esters 2 can be obtained with complete stereoselectivity by reaction of different 2-chloro-3-hydroxy ketones 3 or esters 4 and CrCl₂. A comparative study of the results of synthesis of ketones 1 with CrCl₂ or samarium is performed. A mechanism to explain both β-elimination reactions has been proposed.     

1,4-Asymmetric induction in the titanium-mediated aldol reactions of α-benzyloxy methyl ketones

Good levels of 1,4-anti asymmetric induction are obtained in the TiCl₃(i-PrO)-mediated aldol reaction of α-benzyloxy methyl ketones with achiral aldehydes. Such methodology represents a new approach to the substrate-controlled acetate aldol reaction, which can be useful to design more efficient synthesis.     

Regioselective reactions of β-aminovinyl trifluoromethyl ketones with tosyl isocyanate

The NH- and α-CH-insertion reactions of tosyl isocyanate with N-monosubstituted and N,N-disubstituted trifluoromethyl-containing enaminones have been studied. The regioselectivity of N-tosylcarbomoylation of N-monosubstituted β-aminovinyl trifluoromethyl ketones depends on the structure of enaminones, the reaction temperature, the nature of solvent and catalyst. The Z configuration of fluorinated vinylogous sulphonylurea 3e was deduced from X-ray analysis. The reaction of N,N-disubstituted enaminone 5a with tosyl isocyanate gave the product mixture of electrophilic attack on either the α-CH- or the oxygen atom of COCF₃ group—vinylog of sulfonylurea 6a and tosylamide 7a, correspondingly.     

An atom-efficient palladium-catalyzed cross-coupling reaction of triarylbismuths with acid chlorides: synthesis of diaryl and alkyl aryl ketones

The cross-coupling reaction of triarylbismuths with acid chlorides using a catalytic amount of PdCl₂/PPh₃ afforded the corresponding ketones in high yields. The reactions of aromatic and aliphatic acid chlorides occurred with atom efficiency, as 3 equiv of acid chlorides coupled effectively with 1 equiv of triarylbismuths to yield 3 equiv of the corresponding diaryl and alkyl aryl ketones.     

Hetero-Diels-Alder reaction of photochemically generated α-hydroxy-o-quinodimethanes with trifluoromethyl ketones

Hetero-Diels-Alder reaction of α-hydroxy-o-quinodimethanes photochemically generated from o-tolualdehydes with trifluoromethyl ketones gave a mixture of hemiacetals and hydroxyaldehydes in fairly good yields. Their subsequent oxidation with PCC provided 1-isochromanones as formal oxidative [4+2] cycloaddition products. In contrast, similar reaction of aromatic ketones such as o-methylbenzophenone, 1-indanone, and α-tetralone gave exclusively the corresponding ketones having (trifluoromethyl)methylol groups at the o-position.     

One-pot three-component synthesis of functionalized spirolactones by means of reaction between aromatic ketones, dimethyl acetylenedicarboxylate, and N-heterocycles

A simple and convenient one-pot multi-component reaction has been described for the synthesis of functionalized spirolactones. This strategy demonstrated three-component reaction between aromatic ketones (11H-indeno[1,2-b]quinoxalin-11-one) and dimethyl acetylenedicarboxylate (DMAD) in the presence of N-heterocycles, such as pyridine, quinoline, and isoquinoline in CH₂Cl₂ at ambient temperature without use of any catalyst or activator.     

Efficient synthesis of β-acetamido ketones using BF3/Et2O: a fertile approach toward avoiding usage of acetyl chloride

Abstract

A simple and efficient one pot synthesis of β-acetamido ketones from reaction of aldehydes, enolizable ketones, alkyl/aryl nitriles, and BF₃/Et₂O catalyst under microwave irradiations is described. This method allows synthesis of β-acetamido ketones without using corrosive and hazardous acetyl chloride. It is applicable for diversified aldehydes and active methylene ketones supported by synthesizing varieties of β-acetamido ketones. As per literature, majority of synthetic methods of β-acetamido ketones are restricted to use of acetonitrile lonely, as a nitrile component. This method is found to be equally effective for range of nitriles, also. Key features of reported method are simple reaction protocol, better yields, shorter reaction time, and nonhazardous reaction conditions which support the “Green Chemistry approach.”     

Palladium-catalyzed redox cascade for direct β-arylation of ketones

Herein we report a full article about the detailed design and development of two palladium-catalyzed redox cascade methods that enable direct β-arylation of ketones. Palladium-catalyzed ketone dehydrogenation, aryl-X bond activation and conjugate addition were merged into a redox-neutral catalytic cycle. Non-metal-based aryl electrophiles were used as both the oxidant and the aryl source. The β-arylation with aryl iodides was achieved site-selectively with Pd(TFA)₂/P(i-Pr)₃ as the precatalyst and AgTFA as the iodide scavenger. Both cyclic and linear ketones can react to give β-aryl ketones with excellent functional group tolerance. The β-arylation with diaryliodonium salts was realized without stoichiometric heavy metal additives, and proved to be redox-neutral. A wider substrate scope regarding aryl groups and ketones was obtained for the arylation with diaryliodonium salts, and the possible involvement of palladium nanoparticles as the active catalyst was examined and discussed.     

Ruthenium complexes that incorporate a chiro-inositol derived diphosphinite ligand as catalysts for asymmetric hydrogenation reactions

The diol, 1d-1,2,5,6-tetra-O-methyl-chiro-inositol (D-9), can be conveniently prepared from 1d-chiro-inositol using a series of standard protection/deprotection steps. Treatment of D-9 with Ph₂PCl gives the chiral diphosphinite, 1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol (D-10). The structure of D-10 has been determined by X-ray crystallography. Using 1l-chiro-inositol as starting material and following the same synthetic sequence used to produce D-10, the other enantiomer of this diphosphinite, 1l-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol (L-10) can also be obtained. Ruthenium complexes of these diphosphinite ligands can be conveniently prepared through ligand substitution reactions with appropriate substrate complexes. Thus, treatment of [RuCl₂(COD)]_n with D-10 in the presence of triethylamine produces the bis(diphosphinite) complex, RuHCl{κ²(P,P)-1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol}₂ (11). In addition, reaction between RuCl₂(PPh₃)₃, D-10 and (1R,2R)-(+)-1,2-diphenylethylenediamine gives the mono(diphosphinite) complex, RuCl₂{κ²(P,P)-1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol}{κ²(N,N)-(1R,2R)-(+)-1,2-diphenylethylenediamine} (12). The closely related complex RuCl₂{κ²(P,P)-1d-3,4-bis(O-diphenylphosphino)-1,2,5,6-tetra-O-methyl-chiro-inositol}{κ²(N,N)-(1S,2S)-(−)-1,2-diphenylethylenediamine} (13) can be obtained in a similar manner using (1S,2S)-(−)-1,2-diphenylethylenediamine in place of the corresponding (+)-isomer. These new chiral, diphosphinite complexes catalyse the hydrogenation of the ketones acetophenone and 3-quinuclidinone to give the corresponding alcohols with low to moderate enantiomeric excesses. The complexes are not catalytically active for the hydrogenation of the olefin dimethylitaconate or the α-ketoester methyl benzoylformate.     

Amberlyst-15-promoted efficient 2-halogenation of 1,3-keto-esters and cyclic ketones using N-halosuccinimides

A simple and rapid process has been developed for the α-monohalogenation of 1,3-keto-esters with N-halosuccinimides catalyzed by Amberlyst-15^® at room temperature to produce the corresponding 2-halo 1,3-keto-esters in high yields. This protocol also extended to α-halogenation of cyclic ketones.     

The Mukaiyama-Michael addition of a β,β-dimethyl substituted silyl ketene acetal to α,β-unsaturated ketones using tetra-n-butylammonium bibenzoate as a nucleophilic catalyst

The Michael addition of a β,β-dimethyl substituted silyl ketene acetal [Me₂CC(OMe)OSiMe₃] to α,β-unsaturated ketones, namely, 2-cyclopentenone, 2-cyclohexenone, 3-methyl-2-cyclohexenone, isophorone, methyl vinyl ketone and mesityl oxide occurs smoothly in the presence of the nucleophilic catalyst, tetra-n-butyl ammonium bibenzoate (TBABB) in THF giving the corresponding 1,4-adducts in excellent yields.