Hydroalkylation of Alkenes Using Alkyl Iodides and Hantzsch Ester under Palladium/Light System

The hydroalkylation of alkenes using alkyl iodides with Hantzsch ester as a hydrogen source occurred smoothly under a Pd/light system, in a novel, tin-free Giese reaction. A chemoselective reaction at C­(sp³)–I in the presence of a C­(sp²)–X (X = Br or I) bond was attained, which allowed for the stepwise functionalization of two types of C–X bonds in a one-pot procedure

Cyanoborohydride-Promoted Radical Arylation of Benzene

Radical biaryl coupling of iodoarenes and benzene can be effectively promoted by tetrabutylammonium cyanoborohydride with air under photoirradiation conditions using a Xe lamp. The utility of this methodology is highlighted by its functional group tolerance and chemoselectivity

Reductive Bromine Atom-Transfer Reaction

Atom-transfer radical (ATR) reactions of alkenes with R–X usually give products having new C–C and C–X bonds at the adjacent carbons. However, when the reaction was carried out under irradiation using a low-pressure Hg lamp, addition/reduction products were obtained in good yield. Hydrogen bromide, formed by H-abstraction of a bromine radical from alkenes, is likely to play a key role in the reductive ATR reaction

Rhodium-Catalyzed Decarbonylative C–H Arylation of 2‑Aryloxybenzoic Acids Leading to Dibenzofuran Derivatives

Rhodium-catalyzed intramolecular C–H arylation of 2-aryloxybenzoic acids proceeded accompanied by decarbonylation to give dibenzofuran derivatives in high yields. The present reaction is widely applicable to substrates bearing various functionalities

Synthesis of Alkyl Aryl Ketones by Pd/Light Induced Carbonylative Cross-Coupling of Alkyl Iodides and Arylboronic Acids

Alkyl aryl ketones were synthesized by the carbonylative cross-coupling reaction of alkyl iodides and arylboronic acids under combined Pd/light conditions. In this reaction, it is likely that an acylpalladium species would be formed via carbonylation of the alkyl radical, which would then undergo transmetalation of an arylboronic acid to give the corresponding acyl(aryl)palladium species, ready to undergo reductive elimination to yield the alkyl aryl ketone

Flow Update for the Carbonylation of 1‑Silyl-Substituted Organolithiums under CO Pressure

The generation of, and subsequent reactions with, 1-silyl-substituted organolithiums with CO was carried out using serially connected flow microreactors. The flow system proved to be quite useful for the carbonylation of silyl-substituted organolithiums under slightly pressurized conditions of CO, which was created conveniently by the use of a back-pressure regulator. This flow system, coupled with heating, accelerated the carbonylation reaction of 1-silyl-substituted organolithiums and allowed the stable silyl-substituted alkyllithium, 1,3-disilylallyllithium, which was not effective in a batch-flask reaction under a CO atmosphere, to participate in an efficient carbonylation reaction

Bromine Radical-Mediated Sequential Radical Rearrangement and Addition Reaction of Alkylidenecyclopropanes

Bromine radical-mediated cyclopropylcarbinyl-homoallyl rearrangement of alkylidenecyclopropanes was effectively accomplished by C–C bond formation with allylic bromides, which led to the syntheses of 2-bromo-1,6-dienes. A three-component coupling reaction comprising alkylidenecyclopropanes, allylic bromides, and carbon monoxide also proceeded well to give 2-bromo-1,7-dien-5-ones in good yield

RuHCl(CO)(PPh₃)₃‑Catalyzed α‑Alkylation of Ketones with Primary Alcohols

The α-alkylation reaction of ketones with primary alcohols to give α-alkylated ketones was achieved using RuHCl(CO)(PPh₃)₃ as a catalyst in the presence of Cs₂CO₃ as a base. This reaction proceeds via an aldol condensation of ketones with aldehydes, formed via transfer dehydrogenation of alcohols, to give α,β-unsaturated ketones, which then undergo transfer hydrogenation with primary alcohols to give α-alkylated ketones and aldehydes, the latter of which participate in the next catalytic cycle. While the reaction of aliphatic primary alcohols was sluggish compared with that of benzylic alcohols, a catalytic amount of 1,10-phenanthroline was found to promote the alkylation dramatically

Radical Addition of Alkyl Halides to Formaldehyde in the Presence of Cyanoborohydride as a Radical Mediator. A New Protocol for Hydroxymethylation Reaction

Hydroxymethylation of alkyl halides was achieved using paraformaldehyde as a radical C1 synthon in the presence of tetrabutylammonium cyanoborohydride as a hydrogen source. The reaction proceeds via a radical chain mechanism involving an alkyl radical addition to formaldehyde to form an alkoxy radical, which abstracts hydrogen from a hydroborate anion

Synthesis of Fluorenones through Rhodium-Catalyzed Intramolecular Acylation of Biarylcarboxylic Acids

An efficient approach to the synthesis of fluorenones via the rhodium-catalyzed intramolecular acylation of biarylcarboxylic acids was developed. Using this procedure, fluorenones with various substituents can be synthesized in good to high yields. This work marks the first recorded use of catalytic intramolecular acylation to synthesize fluorenones