Theoretical insight into phosphoric acid-catalyzed asymmetric conjugate addition of indolizines to α,β-unsaturated ketones

A theoretical investigation of the mechanism and origin of enantioselectivity for phosphoric acid-catalyzed asymmetric conjugate addition of indolizines to α,β-unsaturated ketones.     

An Efficient One-pot Synthesis of β-Amino/β-Acetamido Carbonyl Compounds via ZrCl4-catalyzed Mannich-type Reaction

Zirconium(IV) chloride catalyzed efficient one-pot synthesis of β-amino/β-acetamido carbonyl compounds at room temperature is described. In the presence of ZrCl4, the three-component Mannich-type reaction via a variety of in situ generated aldimines, with various ketones, aromatic aldehydes and aromatic amines in ethanol, led to the formation of β-amino carbonyl compounds and the four-component Mannich-type reaction of aromatic aldehydes with various ketones, acetonitrile and acetyl chloride resulted in the corresponding β-acetamido carbonyl compounds in high to excellent yields. This methodology has also been applied towards the synthesis of dimeric β-amino/β-acetamido carbonyl compounds.     

Synthesis of Novel Derivatives of （R）-Cysteine and Their Application in Asymmetric Reduction of Prochiral Ketones

ovel chiral β-amino alcohols containing sulfide or sulfonyl groups were synthesized from （R）-cysteine. Their chiral induction in the asymmetric borane reduction of prochiral ketones was investigated. Optically active secondary alcohols with moderate or high e. e. values were obtained, and the causes of different enantioselectivities between these two sulfur-containing chiral β-amino alcohols were researched.     

Lewis Base Organocatalyzed Enantioselective Hydrosilylation of α-Keto Ketimines

A chiral Lewis base organocatalyzed enantioselective hydrosilylation ofa-keto ketimines was investigated.The reactions afforded various enantioenriched a-amino ketones with good yields（up to 95％） in moderate to good enantioselectivities（up to 98％ e.e.）.Furthermore,one of the products was reduced to a chiral 1,2-amino alcohol.Following cyclization of it with triphosgene generated a cannabinoid receptor 1 （CB 1） inhibitor with good diastereoselectivity.     

Synthesis of Cyclohexyl and Isopropyl Ketones from Benzimidazole Methiodide Salt and Grignard Reagents

The reaction of 2-alkyl-l, 3-dimethylbenzimidazolinm salts with Grignard reagents gave addition products which were hy-drelyzed to give ketones. A new method for the preparation of cyclohexyl ketones and isopropyl ketones is provided.     

Reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica chloride under solvent free conditions

<正>A simple and convenient procedure for the preparation of amines from aldehydes and ketones with sodium borohydride activated by silica chloride as a catalyst under solvent-free conditions is described.A variety of aliphatic and aromatic aldehydes,ketones and amines when mixed with NaBH_4/silica chloride at room temperature,afforded excellent yield of the corresponding amines.     

Novel synthetic method for ketones from substituted benzimidazolium salts and Grignard reagents

A new synthetic method of ketones from substituted benzimidazolium salts and Grignard reagents is reported. The influences of the various Grignard reagents on the yield of ketones and the mechanism are discussed.     

Microwave-assisted synthesis of α-hydroxy aromatic ketones from α-bromo aromatic ketones in water

A reaction ofα-bromo aromatic ketones in water with microwave irradiation gave the correspondingα-hydroxy aromatic ketones in good yields.The use of microwaves was found to significantly improve yields and shorten the reaction time.This reaction afforded a very clean,convenient method for the synthesis ofα-hydroxy aromatic ketones.     

Enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via β-elimination/cycloaddition sequence

A mild and efficient enantioselective one-pot synthesis of β-sulfonyl ketones and trisubstituted tetrahydrothiophenes via introducing 1,4-dithiane-2,5-diol to the simple kinetic resolution of β-sulfonyl ketones has been described herein. The one-pot reaction sequence including kinetic resolution and cascade sulfa-Michael/Aldol reaction proceeded successively to afford corresponding sulfonyl ketones and tetrahydrothiophenes with high enantioselectivities (85%–98% ee and 84%–95% ee, respectively).     

SmI_2-promoted imino-Reformatsky reaction for facile synthesis of enantioenriched β-amino acid esters

A facile and efficient method for the stereoselective synthesis of β-amino acid esters via SmI2-promoted imino-Reformatsky reaction is described.Asymmetric addition of tert-butyl bromoacetate to N-tert-butanesulfinyl aldimines afforded β-amino acid esters in moderate to high yields with excellent diastereoselectivities.The synthetic utilities of the tert-butyl β-amino acid esters were expanded by the preparation of β-lactams and 3-aminoindan-1-ones derivatives.     

非晶态介孔 FeAlP 催化剂用于合成 1,5-苯二氮类化合物

 A simple and versatile method for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones in the presence of solvents and under solvent-free conditions that used an amorphous mesoporous iron aluminophosphate as catalyst was developed. High yields with excellent selectivity were obtained with a wide variety of ketones under mild reaction conditions. The catalyst had the advantages of ease of preparation, ease of handling, simple recovery, reusability, non toxicity, and being inexpensive.     

PEG-OSO3H as an efficient and recyclable catalyst for the synthesis of β-amino carbonyl compounds via the Mannich reaction in PEG-H2O

Sulfuric acid-modified polyethylene glycol 6000（PEG-OSO₃H） was applied as an efficient and recyclable catalyst for the synthesis ofβ-amino carbonyl compounds via the Mannich reaction between aldehydes,aromatic ketones and aromatic amines at room temperature using PEG400-H₂O（1:1） as environment-friendly solvents.The reactions were completed in short times and mild reaction conditions with good to excellent yields.     

A novel oxygen-dependent deoximation by nitric oxide

A variety of aldoximes and ketoximes were oxidized to corresponding aldehydes and ketones by nitric oxide in the presence of oxygen.A presumed mechanism was suggested.     

Direct oxidative C(sp3) -H cyanation of secondary benzylic ethers

A practical and efficient oxidative CH cyanation of secondary benzylic ethers with TMSCN in the presence of DDQ is described for the first time. The metal-free process is well tolerated with a wide variety of electronically varied α-monosubstituted isochromans for the synthesis of isochromans bearing α-aryl α-cyano substituent patterns.     

Schiff-base Amino Alcohol-zinc Complex for Enantioselective Addition of Phenylacetylene to Aromatic Ketones

A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%（molar fraction）, an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc.     

A Convenient Synthesis of Conjugated Acetylenic Ketones by Copper(l)-Catalyzed under Microwave Irradiation

Alkynyl ketones are useful precursors and intermediates in synthetic organic chemistry1 and has evoked considerable interest. A number of methods for the synthesis of conjugated acetylenic ketones involve the reaction a metal acetylide with an acyl chlorides or another carboxylic acid derivative have been developed 2. Recently, the synthesis of α, β-conjugated acetylenic ketones catalyzed by Pd(Ⅱ) or by copper(Ⅰ)pd(Ⅱ) reaction of 1-alkynes and acyl chlorides have been described. The acylation of terminal alkynes by acyl chlorides in the presence of catalytic amounts copper(Ⅰ) salts leading to α, β-conjugated acetylenic ketones has also been reported. However, many of these reactions suffer from lack of high pressure (17 atm), long reaction time (30 h)and require low temperatures (-78℃). Our work involves the synthesis of conjugated acetylenic ketones via the reaction of terminal alkynes with aroyl chlorides in the presence of cuprous iodide under microwave irradiation conditions.     

PhIO-mediated Synthesis of Ketones from Alkynes and Alkenes

A facile and efficient method for the preparation of methyl ketones was developed in the reaction of alkynes and alkenes with PhIO-BF3·Et2O.The reaction features mild conditions,short time and metal-free catalyst.The possible mechanism for the formation of methyl ketones was proposed.H2O functions as both a nucleophile and an oxygen source.     

Tributylphosphine-catalyzed reaction of ethanethiol with alkynyl ketones

A stereoselective and effective method for the synthesis of vinyl thioethers has been developed.This method is based on the Michael addition of ethanethiol to various alkynyl ketones using 10 mol%of tributylphosphine as catalyst.Most of alkynyl ketones react with ethanethiol in this system to yield mainly Z-isomer of vinyl thioether adducts,only in one case mainly E-isomer of vinyl thioether adducts was observed.     

A novel,green 1-glycyl-3-methyl imidazolium chloride-copper(Ⅱ) complex catalyzed C-H oxidation of alkyl benzene and cyclohexane

A variety of alkyl-arenes and cyclohexane were converted to the corresponding ketones with NaCIO as the oxidant in the presence of l-glycyl-3-methyl imidazolium chloride-copper(Ⅱ) complex.This method contains simplified product isolation and catalyst recycling,affording benzylic C-H oxidation of alkyl-arenes imparting high yield of ketones.Furthermore,complex could be reused seven times without a significant loss of its catalytic activity.     

Iron-catalyzed ketonization of 2-aryl-1,1-dibromoalkenes with KOAc:Synthesis of α-acetoxy aryl ketones via a Michael-like addition process

A novel and convenient iron-catalyzed ketonization of 2-aryl-1,1-dibromoalkenes with KOAc has been achieved.A series ofα-acetoxy aryl ketones were prepared with moderate yields via 2-carbon position functionalization of 2-aryl-1,1-dibromoalkenes.