Indium(III)-Catalyzed Knoevenagel Condensation of Aldehydes and Activated Methylenes Using Acetic Anhydride as a Promoter

The combination of a catalytic amount of InCl₃ and acetic anhydride remarkably promotes the Knoevenagel condensation of a variety of aldehydes and activated methylene compounds. This catalytic system accommodates aromatic aldehydes containing a variety of electron-donating and -withdrawing groups, heteroaromatic aldehydes, conjugate aldehydes, and aliphatic aldehydes. Central to successfully driving the condensation series is the formation of a geminal diacetate intermediate, which was generated in situ from an aldehyde and an acid anhydride with the assistance of an indium catalyst

Production of Quaternary α‑Aminonitriles by Means of Indium-Catalyzed Three-Component Reaction of Alkynes, Amines, and Trimethylsilyl Cyanide

A novel synthesis of α-aminonitriles is described via an indium-catalyzed three-component coupling reaction of alkynes, amines, and trimethylsilyl cyanide (Me₃SiCN). Hydroamination of alkynes with a subsequent nucleophilic addition of Me₃SiCN resulted in a novel approach to quaternary α-aminonitrile derivatives

Syntheses of RuHCl(CO)(PAr₃)₃ and RuH₂(CO)(PAr₃)₃ Containing Various Triarylphosphines and Their Use for Arylation of Sterically Congested Aromatic C–H Bonds

A series of ruthenium complexes, RuHCl­(CO)­(PAr₃)₃ and RuH₂(CO)­(PAr₃)₃, containing various triarylphosphines were synthesized. Screening of these complexes as catalysts for direct arylation of sterically congested ortho C–H bonds of aromatic ketones improved the yields of the arylation products

Palladium-Catalyzed Reductive Conversion of Acyl Fluorides via Ligand-Controlled Decarbonylation

Ligand-controlled non-decarbonylative and decarbonylative conversions of acyl fluorides were developed using a Pd­(OAc)₂/Et₃SiH combination. When tricyclohexylphosphine (PCy₃) was used as the ligand, aldehydes were obtained as simple reductive conversion products. The use of 1,2-bis­(dicyclohexylphosphino)­ethane (Cy₂P­(CH₂)₂PCy₂, DCPE) as the ligand, however, favored the formation of hydrocarbons, which are decarbonylative reduction products

Gallium-Catalyzed Reductive Chlorination of Carboxylic Acids with Copper(II) Chloride

Described herein is the direct chlorination of carboxylic acids using copper­(II) chloride via a gallium­(III)-catalyzed reduction in the presence of a hydrosiloxane. During this reductive chlorination, the counteranions of CuCl₂ functioned as a chloride source

Ruthenium-Catalyzed Ortho-Selective C–H Alkenylation of Aromatic Compounds with Alkenyl Esters and Ethers

A direct, regioselective alkenylation of aromatic C–H bonds of aryl- and heteroarylpyridines and related compounds with alkenyl esters was developed using Ru­(cod)­(cot) as a catalyst. Aromatic compounds bearing electronically diverse substituents and various heterocyclic directing groups are reacted with alkenyl acetates bearing mono- and disubstituted alkenyl groups with aliphatic and aromatic substituents to give ortho-alkenylation products in high yields. The results of deuterium-labeling experiments and competition reactions using different ratios of the <i>E</i> and <i>Z</i> isomers of β-styryl acetate suggested that the C–H alkenylation proceeded via a ruthenium–alkene intermediate and the C–O bond of the alkenyl acetate was cleaved by β-acetoxy elimination. Two types of catalytically relevant species were identified, and the reactivities of these species, combined with the results of the kinetic studies, suggest that the rate-limiting step is the exchange of the COD ligand with the alkenyl ester. On the basis of the elucidated mechanism, the first catalytic coupling reaction using aromatic C–H bonds with C–O bonds of ethers was also developed