Copper‐Catalyzed Three‐Component Carboazidation of Alkenes with Acetonitrile and Sodium Azide

A copper‐catalyzed three‐component reaction of alkenes, acetonitrile, and sodium azide afforded γ‐azido alkyl nitriles by formation of one C(sp³)−C(sp³) bond and one C(sp³)−N bond. The transformation allows concomitant introduction of two highly versatile groups (CN and N₃) across the double bond. A sequence involving the copper‐mediated generation of a cyanomethyl radical and its subsequent addition to an alkene, and a C(sp³)−N bond formation accounted for the reaction outcome. The resulting γ‐azido alkyl nitrile can be easily converted into 1,4‐diamines, γ‐amino nitriles, γ‐azido esters, and γ‐lactams of significant synthetic value.     

Stereoselective Michael Addition and Michael-aldol Tandem Reaction of Diorganyl Diselenides or Disulfides with Conjugated Alkynones Mediated by Samarium Diiodide

Stereoselective Michael addition and Michael-aldol tandem reaction of diorganyl diselenides and disulfides with conjugated alkynones mediated by samarium diiodide were studied. The reaction temperature was critical for the stereoselectivity, β-Organylselenoalkenones or β-organylthioalkenones and γ-organylselenoallylic alcohols or γ-organylthioallylic alcohols were prepared in good yields.     

Palladium‐Catalyzed Cascade Annulation To Construct Functionalized β‐ and γ‐Lactones in Ionic Liquids

A highly efficient and mild palladium‐catalyzed, one‐pot, four‐step cascade annulation has been developed to afford functionalized β‐ and γ‐lactones in moderate to good yields with high regio‐ and diastereoselectivities in ionic liquids. The employment of ionic liquids under mild reaction conditions makes this transformation green and practical. Especially, this reaction provided a novel and convenient methodology for the construction of naturally occurring biologically active β‐ and γ‐lactones.     

Oxidative N‐Heterocyclic Carbene‐Catalyzed γ‐Carbon Addition of Enals to Imines: Mechanistic Studies and Access to Antimicrobial Compounds

The reaction mechanism of the γ‐carbon addition of enal to imine under oxidative N‐heterocyclic carbene catalysis is studied experimentally. The oxidation, γ‐carbon deprotonation, and nucleophilic addition of γ‐carbon to imine were found to be facile steps. The results of our study also provide highly enantioselective access to tricyclic sulfonyl amides that exhibit interesting antimicrobial activities against X. oryzae, a bacterium that causes bacterial disease in rice growing.     

Copper‐Catalyzed γ‐Selective and Stereospecific Allylic Cross‐Coupling with Secondary Alkylboranes

The scope of the copper‐catalyzed coupling reactions between organoboron compounds and allylic phosphates is expanded significantly by employing triphenylphosphine as a ligand for copper, allowing the use of secondary alkylboron compounds. The reaction proceeds with complete γ‐E‐selectivity and preferential 1,3‐syn stereoselectivity. The reaction of γ‐silicon‐substituted allylic phosphates affords enantioenriched α‐stereogenic allylsilanes.     

Single‐Flask Multicomponent Palladium‐Catalyzed α,γ‐Coupling of Ketone Enolates: Facile Preparation of Complex Carbon Scaffolds

A three‐component palladium‐catalyzed reaction sequence has been developed in which γ‐substituted α,β‐unsaturated products are obtained in a single flask by an α‐alkenylation with either a subsequent γ‐alkenylation or γ‐arylation of a ketone enolate. Coupling of a variety of electronically and structurally different components was achieved in the presence of a Pd/Q‐Phos catalyst (2 mol %), usually at 22 °C with yields of up to 85 %. Most importantly, access to these products is obtained in one simple operation in place of employing multiple reactions.     

Direct Catalytic Asymmetric Doubly Vinylogous Michael Addition of α,β‐Unsaturated γ‐Butyrolactams to Dienones

An asymmetric doubly vinylogous Michael addition (DVMA) of α,β‐unsaturated γ‐butyrolactams to sterically congested β‐substituted cyclic dienones with high site‐, diastereo‐, and enantioselectivity has been achieved. An unprecedented DVMA/vinylogous Michael addition/isomerization cascade reaction affords chiral fused tricyclic γ‐lactams with four newly formed stereocenters.     

Ligand‐Controlled Direct γ‐C−H Arylation of Aldehydes

The first example of Pd^II‐catalyzed γ‐C(sp³)?H functionalization of aliphatic and benzoheteroaryl aldehydes has been developed using a transient ligand and an external ligand, concurrently. A wide array of γ‐arylated aldehydes were readily accessed without preinstalling internal directing groups. The catalytic mechanism was studied by performing deuterium‐labelling experiments, which indicated that the γ‐C(sp³)?H bond cleavage is the rate‐limiting step during the reaction process. This reaction could be performed on a gram scale, and also demonstrated its potential application in the synthesis of new mechanofluorochromic materials with blue‐shifted mechanochromic properties.     

Effect of Hydrothermal Time,pH, and Alkali on Crystal Phase and Morphology of Manganese Oxides

γ‐MnOOH nanowires and Mn₃O₄ nanoparticles were prepared in the hydrothermal process. The effect of hydrothermal time, pH, and alkali on morphology and composition of manganese oxides was investigated. The results of XRD, TEM, and SEM showed that the γ‐MnOOH prepared in shorter hydrothermal time was a mixture of nanocubes and nanowires, while in longer hydrothermal time was pure nanowires. Interestingly, increasing the pH of the reaction system from 8 to 10, the mixture of γ‐MnOOH nanowires and Mn₃O₄ nanoparticles was obtained. Alkali types also were discussed in directing the reaction and crystallization of manganese oxides. The product was pure γ‐MnOOH when using NaOH in the system, but a mixture of Mn₃O₄ and γ‐MnOOH was obtained when using NH₃ · H₂O.     

Ligand‐Enabled γ‐C(sp3)−H Olefination of Free Carboxylic Acids

We report the ligand‐enabled C?H activation/olefination of free carboxylic acids in the γ‐position. Through an intramolecular Michael addition, δ‐lactones are obtained as products. Two distinct ligand classes are identified that enable the challenging palladium‐catalyzed activation of free carboxylic acids in the γ‐position. The developed protocol features a wide range of acid substrates and olefin reaction partners and is shown to be applicable on a preparatively useful scale. Insights into the underlying reaction mechanism obtained through kinetic studies are reported.     

Direct synthesis of γ‐substituted phthalides via ortho‐aryl benzoic acid mediated benzyl radical cyclization

Direct synthesis of γ‐substituted phthalids from related ortho‐aryl benzoic acids with 48–85% yield are covered. The direct oxidation in the presence of peroxydisulphate‐copper (II) chloride in aqueous medium was applied. The reaction is highly regioselective and leads exclusively to γ‐butyrolactone, through very stable benzylic radical intermediate.     

Intermolecular [2+2+1] Carbonylative Cycloaddition of Aldehydes with Alkynes,and Subsequent Oxidation to γ‐Hydroxybutenolides by a Supported Ruthenium Catalyst

Intermolecular [2+2+1] carbonylative cycloaddition of aldehydes with alkynes and subsequent oxidation to γ‐hydroxybutenolides is achieved using a supported ruthenium catalyst. A ceria‐supported ruthenium catalyst promotes the reaction efficiently, even with an ambient pressure of CO or without external CO, thus giving the corresponding γ‐hydroxybutenolide derivatives in good to high yields. Moreover this catalyst can be reused with no loss of activity.     

Intermolecular [2+2+1] Carbonylative Cycloaddition of Aldehydes with Alkynes,and Subsequent Oxidation to γ‐Hydroxybutenolides by a Supported Ruthenium Catalyst

Intermolecular [2+2+1] carbonylative cycloaddition of aldehydes with alkynes and subsequent oxidation to γ‐hydroxybutenolides is achieved using a supported ruthenium catalyst. A ceria‐supported ruthenium catalyst promotes the reaction efficiently, even with an ambient pressure of CO or without external CO, thus giving the corresponding γ‐hydroxybutenolide derivatives in good to high yields. Moreover this catalyst can be reused with no loss of activity.     

Titanocene(III)‐Catalyzed Three‐Component Reaction of Secondary Amides,Aldehydes, and Electrophilic Alkenes

An umpolung Mannich‐type reaction of secondary amides, aliphatic aldehydes, and electrophilic alkenes has been disclosed. This reaction features the one‐pot formation of C? N and C? C bonds by a titanocene‐catalyzed radical coupling of the condensation products, from secondary amides and aldehydes, with electrophilic alkenes. N‐substituted γ‐amido‐acid derivatives and γ‐amido ketones can be efficiently prepared by the current method. Extension to the reaction between ketoamides and electrophilic alkenes allows rapid assembly of piperidine skeletons with α‐amino quaternary carbon centers. Its synthetic utility has been demonstrated by a facile construction of the tricyclic core of marine alkaloids such as cylindricine C and polycitorol A.     

Titanocene(III)‐Catalyzed Three‐Component Reaction of Secondary Amides,Aldehydes, and Electrophilic Alkenes

An umpolung Mannich‐type reaction of secondary amides, aliphatic aldehydes, and electrophilic alkenes has been disclosed. This reaction features the one‐pot formation of C N and C C bonds by a titanocene‐catalyzed radical coupling of the condensation products, from secondary amides and aldehydes, with electrophilic alkenes. N‐substituted γ‐amido‐acid derivatives and γ‐amido ketones can be efficiently prepared by the current method. Extension to the reaction between ketoamides and electrophilic alkenes allows rapid assembly of piperidine skeletons with α‐amino quaternary carbon centers. Its synthetic utility has been demonstrated by a facile construction of the tricyclic core of marine alkaloids such as cylindricine C and polycitorol A.     

Electrochemical Oxidative C−H/N−H Coupling between γ‐Lactams and Anilines

A mild method for the direct C?H/N?H coupling between γ‐lactams and anilines through electrochemical oxidation has been developed. The protocol proceeded smoothly without metal catalysts at room temperature to afford γ‐substituted γ‐lactams in good yields. It has been revealed that the quasi‐divided cell which provided high current density on the anode was crucial for this reaction.     

Stereoselective Iodolactonization of 4‐Allenoic Acids with Efficient Chirality Transfer: Development of a New Electrophilic Iodination Reagent

A highly stereoselective iodolactonization of 4‐allenoic acids with a new sterically demanding electrophilic iodination reagent to afford optically active γ‐butyrolactones has been developed. The reaction shows high efficiency of axial chirality transfer and excellent Z/E selectivity and has been applied to the synthesis of chiral cis‐β,γ‐disubstituted γ‐butyrolactones to give very high diastereomeric and enantiomeric excess values. The reaction has been successfully utilized in the synthesis of naturally occurring compounds (+)‐cis‐whisky lactone and (+)‐cis‐3‐methyl‐4‐decanolide.     

Efficient conversion of fructose to 5‐hydroxymethylfurfural by functionalized γ‐Al2O3 beads

Millimeter size γ‐Al₂O₃ beads were prepared by alginate assisted sol–gel method and grafting organic groups with propyl sulfonic acid and alkyl groups as functionalized γ‐Al₂O₃ bead catalysts for fructose dehydration to 5‐hydroxymethylfurfural (5‐HMF). Experiment results showed that the porous structure of γ‐Al₂O₃ beads was favorable to the loading and dispersion of active components, and had an obvious effect on the properties of the catalyst. The lower calcination temperature of γ‐Al₂O₃ beads increased the specific surface area, the hydrophobicity and the activity of catalysts. Competition between the reaction of alkyl groups and ‐SH groups with surface hydroxyl during the preparation process of the catalyst influenced greatly the acid site densities, hydrophobic properties and activity of the catalyst. With an increase in the alkyl group chain, the hydrophobicity of catalysts increased obviously and the activity of the catalyst was enhanced. The most hydrophobic catalyst C₁₆‐SO₃H‐γ‐Al₂O₃–650°C exhibited the highest yield of 5‐HMF (84%) under the following reaction conditions: reaction medium of dimethylsulfoxide/H₂O (V/V, 4:1), catalyst amount of 30 mg, temperature of 110°C and reaction time of 4 hr.     

Pd(II)‐Catalyzed Tandem Enantioselective Methylene C(sp3)−H Alkenylation–Aza‐Wacker Cyclization to Access β‐Stereogenic γ‐Lactams

Herein, we describe an unprecedented cascade reaction to β‐stereogenic γ‐lactams involving Pd(II)‐catalyzed enantioselective aliphatic methylene C(sp³)?H alkenylation–aza‐Wacker cyclization through syn‐aminopalladation. Readily available 3,3′‐substituted BINOLs are used as chiral ligands, providing the corresponding γ‐lactams with broad scope and high enantioselectivities (up to 98 % ee).     

Ligand‐Enabled PdII‐Catalyzed Iterative γ‐C(sp3)−H Arylation of Free Aliphatic Acid

C?H functionalization of aliphatic carboxylic acids without attaching exogenous auxiliary has been so far limited at the proximal β‐position. In this work, we demonstrate a ligand enabled palladium catalyzed first regioselective distal γ‐C(sp3)?H functionalization of aliphatic carboxylic acids without incorporating an exogenous directing group. Aryl iodides containing versatile functional groups including complex organic molecules are well tolerated with good to excellent yields during the γ‐C(sp3)?H arylation reaction. Interestingly, weak coordination of carboxylate group can be further extended for sequential hetero di‐arylation. Application of the protocol has been showcased by synthesizing substituted α‐tetralone. Mechanistic investigations have been carried out to shed light on the reaction pathway.