A Pd-catalyzed transfer hydrogenation of various N-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 N-heteroaromatic compounds among which imidazo[1,2-a]pyridine derivatives were for the first time selectively reduced to 5,6,7,8-tetrahydroimidazo[1,2-a]pyridines, which are the core structural motifs of an inhibitor of human O-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.

A practical and highly efficient method for the construction of a variety of sulfonamides mediated by I2 was demonstrated. The reaction proceeds readily at room temperature using a variety of sodium sulfinates and amines or ammonia in water in a metal-, base-, ligand-, or additive-free protocol. Primary, secondary and tertiary sulfonamides were obtained in good to excellent yields with a broad range of substrate tolerability.

Two novel and synthetically useful reaction patterns of organolithium compounds with nitriles are reported to afford pyridine derivatives as the final products. Both 1-lithio-1,3-dienes and 1,4-dilithio-1,3-dienes, which can be easily generated in situ by lithiation of their corresponding iodo compounds, react with nitriles in the presence of HMPA to form substituted pyridines including 2,2'-bipyridines and tetrahydroisoquinolines in high yields.

Halodifluoromethyl and trifluoromethyl-containing compounds can act various roles via selective cleavage modes to access more valuable fluorinated or nonfluorinated molecules.

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 sp(3)-hybridized carbon and the use of a benzylic carboxylic acid as a source of carbonyl compounds.

Photoredox-catalyzed decarboxylative alkylation of silyl enol ethers has been developed. Diverse functionalized aryl alkyl ketones were afforded in modest to good yields using N-(acyloxy)phthalimide as an easy access alkyl radical source under mild and operationally simple conditions. The excellent performance of drug molecules such as fenbufen and indomethacin and naturally occurring carboxylic acids such as stearic acid and dehydrocholic acid further demonstrated the practicability of the reaction.

A synergistic Cu/Fe-catalyzed aerobic oxyphosphorylation of alkynes or alkynyl carboxylic acids with H-phosphonate is disclosed. The useful β-ketophosphonate products were obtained in good yields under oxygen atmosphere in a novel way. This reaction exhibits a wide substrate scope, and the mechanistic experiments indicate that a radical mechanism forms both C-P and C═O bonds simultaneously. This mechanism contrasts existing aerobic difunctionalization of alkynes.

-042Highly Regio-and Stereoselective 1,1-Cycloaddition of Carbon Monoxide with 1,4-Dilithio-1,3-dienes. Novel Synthetic Methods for 3-Cyclopenten-1-one Derivatives.-Dilithio-1,3-dienes, generated in situ from the corresponding diiodo dienes and tBuLi, give with CO cleanly trans-3-cyclopenten-1-ones (III) in excellent yields after final hydrolysis. The subsequent addition of alkyl halogenides or dimethyl sulfate to the carbonylation reaction mixture followed by hydrolysis affords the corresponding 2,5-dialkyl cyclopentenones, also with excellent regio-and diastereoselectivity.