Fe-Catalyzed Double Cross-Dehydrogenative Coupling of 1,3-Dicarbonyl Compounds and Arylmethanes

Fe-catalyzed tandem cross-dehydrogenative coupling of the methyl group in arylmethanes with 1,3-dicarbonyl compounds has been developed. The reaction affords one new C­(sp³)–C­(sp²) bond and one new C­(sp³)–C­(sp³) bond in a one-pot protocol. Further study suggests that this reaction might start with a Friedel–Crafts-type reaction (cross-dehydrogenative arylation) followed by cross-dehydrogenative coupling with an activated methylene group under mild oxidative conditions

Pd-Catalyzed Regioselective Arylboration of Vinylarenes

A palladium-catalyzed 1,2-arylboration of vinylarenes with aryldiazonium tetrafluoroborates and bis­(pinacolato)­diboron has been disclosed. It is reported for the first time that styrene derivatives can be successfully employed as good substrates for 1,2-arylboration of alkenes. Mechanistic studies suggest that no Pd–H reinsertion occurred under our standard conditions, which is the key for the success of this transformation

Copper-Catalyzed C(sp²)–H Difluoroalkylation of Aldehyde Derived Hydrazones with Diboron as Reductant

An efficient and general method for C­(sp²)–H difluoroalkylation of aldehyde derived hydrazones via a Cu^II/B₂pin₂-catalyzed reaction between difluoroalkyl bromides and hydrazones was developed. In this reaction, both aromatic and aliphatic difluoroalkylated aldehyde derived hydrazones could be achieved in good to excellent yields. For some heteroaromatic aldehyde derived hydrazones, two fluoroacetates could be introduced onto the final products. A preliminary mechanism study manifested that a difluoroalkyl radical via SET pathway was involved in the reaction. In addition, the catalytic diboron reagent plays an indispensable role in this transformation

Palladium-Catalyzed Arylboration of Bicyclic Alkenes

A palladium-catalyzed arylboration of norbornene or norbornadiene with aryl halides and bis­(pina­colato)­diboron has been disclosed. Mechanistic studies suggest that the reaction proceeds under a Catellani-type coupling to render versatile multifunctionalized alkylboranes in good yields. This reaction is complementary to the existing methods and is well tolerable with a variety of functional groups and readily scaled-up to a gram scale without deteriorating the yield

Diboron-Assisted Palladium-Catalyzed Transfer Hydrogenation of <i>N</i>‑Heteroaromatics with Water as Hydrogen Donor and Solvent

A Pd-catalyzed transfer hydrogenation of various <i>N</i>-heteroaromatic compounds with B₂pin₂ as a mediator and environmentally benign water as both solvent and hydrogen donor has been disclosed. This reaction proceeded under ambient temperature with a broad range of <i>N</i>-heteroaromatic compounds among which imidazo­[1,2-<i>a</i>]­pyridine derivatives were for the first time selectively reduced to 5,6,7,8-tetrahydroimidazo­[1,2-<i>a</i>]­pyridines, which are the core structural motifs of an inhibitor of human <i>O</i>-GlcNAcase. Mechanistic studies suggested that the new protons in products are from water and Pd–H might be the key intermediate with B₂pin₂ as the H₂O activator

Copper-Catalyzed Radical Difluoroalkylation and Redox Annulation of Nitroalkynes for the Construction of C2-Tetrasubstituted Indolin‑3-ones

An efficient and convenient method with wide applicability for the synthesis of C2-tetrasubstituted indolin-3-ones via copper-catalyzed redox cycloisomerization of nonprefunctionalized nitroalkynes has been developed. This protocol features simple operation, readily available starting materials, good functional group tolerance, broad scope, and diboron as the reductant

Aldehydes and Ketones Formation: Copper-Catalyzed Aerobic Oxidative Decarboxylation of Phenylacetic Acids and α‑Hydroxyphenylacetic Acids

Aromatic aldehydes or ketones from copper catalyzed aerobic oxidative decarboxylation of phenylacetic acids and α-hydroxyphenylacetic acids have been synthesized. This reaction combined decarboxylation, dioxygen activation, and C–H bond oxidation steps in a one-pot protocol with molecular oxygen as the sole terminal oxidant. This reaction represents a novel decarboxylation of an <i>sp</i>³-hybridized carbon and the use of a benzylic carboxylic acid as a source of carbonyl compounds

Rhodium-Catalyzed Intramolecular Cyclization to Synthesize 2‑Aminobenzofurans via Carbene Metathesis Reactions

Herein, we report a new method of synthesizing of 2-aminobenzofuran 3-enes via the formal C–S insertion reaction of alkyne-tethered diazo compounds. Metal carbene, as a kind of active synthetic intermediate, plays a very important role in organic synthesis. Through the carbene/alkyne metathesis strategy, a new donor carbene is produced in situ as a key intermediate, which has different reactions from the donor receptor carbene

Synthesis of Primary Amides via Copper-Catalyzed Aerobic Decarboxylative Ammoxidation of Phenylacetic Acids and α‑Hydroxyphenylacetic Acids with Ammonia in Water

A Cu₂O-catalyzed aerobic oxidative decarboxylative ammoxidation to primary benzamides from phenylacetic acids and α-hydroxyphenylacetic acids is developed. A variety of primary benzamides could be prepared smoothly, in good to excellent yields, by means of a one-pot domino protocol combining decarboxylation, dioxygen activation, oxidative C–H bond functionalization, and amidation reactions

Copper(I)-Catalyzed Chemoselective Reduction of Benzofuran-2-yl Ketones to Alcohols with B₂pin₂ via a Domino-Borylation-Protodeboronation Strategy

A novel copper­(I)-catalyzed chemoselective reduction of the carbonyls of benzofuran-2-yl ketones over furan rings with B₂pin₂ has been developed. This reaction proceeded under mild conditions. High valuable secondary alcohol derivatives of benzofurans were obtained in good to excellent yields with a broad substrate scope. The mechanistic studies suggested that a domino-borylation-protodeboronation pathway was involved in this reaction