Chemoselective Conjugate Reduction Research Articles

In Situ Sulfidation of Pd/C: A Straightforward Method for Chemoselective Conjugate Reduction by Continuous Hydrogenation

A method has been developed for the in situ sulfidation of Pd/C under continuous flow. The approach provides a cheap, sustainable, and operationally convenient method for chemoselective conjugate reduction by continuous hydrogenation. High conversions and excellent selectivities were obtained for olefin reduction in α/β-unsaturated carbonyl compounds in the presence of hydrogenatively sensitive functionalities. The methodology was analyzed with a green metric system to highlight the sustainability features of the process.

A novel transition metal-free conjugate reduction of α,β-unsaturated ketones with tosylhydrazine as a hydrogen source

A novel and efficient method has been developed for the chemoselective conjugate reduction of α,β-unsaturated ketones with tosylhydrazine as a hydrogen source to the corresponding saturated ketones in moderate to good yields. The present protocol does not require the use of transition metal, and is efficient being applicable to a wide range of substrates (25 examples).

ChemInform Abstract: Waste as Catalyst: Tandem Wittig/Conjugate Reduction Sequence to α‐CF3 γ‐Keto Esters that Uses Ph3PO as Catalyst for the Chemoselective Conjugate Reduction.

ChemInform Abstract: Waste as Catalyst: Tandem Wittig/Conjugate Reduction Sequence to α‐CF₃ γ‐Keto Esters that Uses Ph₃PO as Catalyst for the Chemoselective Conjugate Reduction.

Waste as Catalyst: Tandem Wittig/Conjugate Reduction Sequence to α‐CF3 γ‐Keto Esters That Uses Ph3PO as Catalyst for the Chemoselective Conjugate Reduction

Waste as Catalyst: Tandem Wittig/Conjugate Reduction Sequence to α‐CF₃ γ‐Keto Esters That Uses Ph₃PO as Catalyst for the Chemoselective Conjugate Reduction

Replication of biosynthetic reactions enables efficient synthesis of A-factor, a γ-butyrolactone autoinducer from Streptomyces griseus

We report a concise synthesis of A-factor, the prototypical γ-butyrolactone signalling compound of Streptomyces bacteria. In analogy to enzymatic reactions in A-factor biosynthesis, our synthesis features a tandem esterification-Knoevenagel condensation yielding a 2-acyl butenolide and a surprising, chemoselective conjugate reduction of this α,β-unsaturated carbonyl compound using sodium cyanoborohydride.

ChemInform Abstract: An Efficient and Heterogeneous Recyclable Palladium Catalyst for Chemoselective Conjugate Reduction of α,β‐Unsaturated Carbonyls in Aqueous Medium.

AbstractA complete green and convenient strategy for the chemoselective transfer hydrogenation of various α,β‐unsaturated carbonyl compounds using HCOONa as hydrogen source and a polymer‐supported Pd‐NHC catalyst system is given.

An efficient and heterogeneous recyclable palladium catalyst for chemoselective conjugate reduction of α,β-unsaturated carbonyls in aqueous medium

An highly efficient PS-Pd-NHC catalytic system has been developed for chemoselective conjugate reduction of α,β-unsaturated carbonyl compounds providing good to excellent conversion with remarkable chemoselectivity (up to 100%). The developed protocol is more advantageous due to use of HCOONa as hydrogen source, environmentally benign water as solvent and effective catalyst recyclability.

ChemInform Abstract: Chemoselective Conjugate Reduction of α,β-Unsaturated Esters and Lactones Under Mild Conditions.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Chemoselective Conjugate Reduction of α,β‐Unsaturated Ketones Catalyzed by Rhodium Amido Complexes in Aqueous Media.

AbstractIn the presence of HCOONa, Rh2Cl4(C5Me5)2, and the diamine (AMI) α,β‐unsaturated ketones are found to undergo reduction of the C=C double bond with high selectivity.

Chemoselective Conjugate Reduction of α,β-Unsaturated Ketones Catalyzed by Rhodium Amido Complexes in Aqueous Media

Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C=O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C=O to C=C bonds in the transfer hydrogenation of activated alpha,beta-unsaturated ketones. Now we have found that a variety of alpha,beta-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.

Highly Chemoselective Copper-Catalyzed Conjugate Reduction of Stereochemically Labile α,β-Unsaturated Amino Ketones

Highly chemoselective conjugate reduction of chiral alpha,beta-unsaturated amino ketones has been developed by using triisopropyl phosphite ligated copper hydride complex. The highlights of the method are wide substrate compatibility and exceptional chemoselectivity.

A Facile and Chemoselective Conjugate Reduction Using Polymethylhydrosiloxane (PMHS) and Catalytic B(C6F5)3.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

A facile and chemoselective conjugate reduction using polymethylhydrosiloxane (PMHS) and catalytic B(C6F5)3

A highly chemoselective conjugate reduction of electron-deficient Michael acceptors, including alpha,beta-unsaturated ketones, carboxylic esters, nitriles and nitro compounds with PMHS in the presence of catalytic B(C6F5)3 is described.

Synthetic Applications of Stryker’s Reagent

Hexa-m-hydrohexakis(triphenylphosphine) hexacopper, also known as Stryker’s reagent, is a well-characterized copper(I) hydride reagent for chemoselective conjugate reduction of a,b-unsaturated ketones, [1-7] esters, [1] [4] lactones, [8] nitriles, [9] aldehydes, [3] sulfones, and sulfonates. [6] The reaction is highly chemoselective, and isolated alkenes, halogens, and typical oxygenated functionalities are not reduced under the reaction conditions. [1-7] In the presence of several silanes and a catalytic quantity of Stryker’s ­reagent, ketones and aldehydes are reduced to the corresponding alcohols. [10] The conjugated reduction can be performed either stoichiometrically or catalytically in the presence of reducing agents, and the reaction intermediates can be used for further C-C bond formations. [9] [11-14] Stryker’s reagent is commercially available, but various methods have been developed over the years for its preparation. [15-19]

Chemoselective Conjugate Reduction of α,β-Unsaturated Esters and Lactones Under Mild Conditions

Several pyranose-derived α,β-unsaturated lactones and esters undergo chemoselective conjugate reduction by a tandem benzenethiol addition-tributyltin hydride reduction, without isolation of the intermediates, to the corresponding carbonyl compounds in good yield. The method is compatible with the presence of various protecting groups.

Conjugate reduction of polyfunctional α,β-unsaturated carbonyl compounds using [(Ph 3P)CuH] 6. Compatibility with halogen, sulfonate, and γ-oxygen and sulfur substituents

In contrast to organocuprate conjugate addition and standard methods for conjugate reduction, use of the stable copper(I) hydride cluster, [(Ph 3P)CuH] 6, allows chemoselective conjugate reduction of α,β-unsaturated carbonyl compounds substituted at the γ-position with leaving groups. In addition, the compatibility of the conjugate reduction with organic halides and sulfonate groups is demonstrated.

Organo tin nucleophiles IV. Palladium catalyzed conjugate reduction with tin hydride

Highly chemoselective conjugate reduction of α,β-unsaturated carbonyl compounds is now possible by using tributyl tin hydride with Pd(PØ 3) 4; an optimization study puts forth the importance of added radical scavenger and proton source in these reductions.