Versatile iridicycle catalysts for highly efficient and chemoselective transfer hydrogenation of carbonyl compounds in water.

Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α-substituted ketones (α-ether, α-halo, α-hydroxy, α-amino, α-nitrile or α-ester), α-keto esters, ß-keto esters and α,ß-unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50 000 at pH 4.5 and required no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of ß-functionalised secondary alcohols, such as ß-hydroxyethers, ß-hydroxyamines and ß-hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis.

Another side of the oxazaphospholidine oxide chiral ortho-directing group.

A new ferrocenyl oxazaphospholidine oxide 3 was synthesized together with its P-epimer 2 in the reaction of ferrocene lithium with phosphoramidite chloride 1. 3 was successfully derivatized into planar chiral 1,2-ferrocenes, including phosphine ligands, via highly diastereoselective ortho-lithiation and subsequent functionalization; these compounds display opposite planar chirality to those obtained from 2. Some of these 1,2-ferrocenes were further lithiated, allowing for the introduction of a free phosphine group at the oxazaphospholidine ring. The X-ray structures of the compounds 2 and 3 as well as those of the new 1,2-ferrocenes 4 and 7 have been determined.

Ruthenium-catalyzed meta sulfonation of 2-phenylpyridines.

A selective catalytic meta sulfonation of 2-phenylpyridines was found to occur in the presence of (arene)ruthenium(II) complexes upon reaction with sulfonyl chlorides. The 2-pyridyl group facilitates the formation of a stable Ru-C(aryl) σ bond that induces a strong para-directing effect. Electrophilic aromatic substitution proceeds with the sulfonyl chloride to furnish a sulfone at the position meta to the chelating group. This new catalytic process offers access to atypical regioselectivity for reactions involving chelation-assisted cyclometalation.

Iridium-catalysed amine alkylation with alcohols in water.

Amines have been directly alkylated with alcohols using 1 mol% [Cp*IrI(2)](2) catalyst in water in the absence of base or other additives.

Synthesis of benzazoles by hydrogen-transfer catalysis.

Transition-metal-catalyzed hydrogen-transfer reactions have been used for the conversion of alcohols into benzimidazoles and aldehydes into benzoxazoles and benzothiazoles.

Regioselective Heck vinylation of electron-rich olefins with vinyl halides: is the neutral pathway in operation?

Highly regioselective vinylation of electron-rich olefins by bromo- as well as chlorostyrenes is effected by palladium catalysis with either mono- or bidentate phosphines in a molecular solvent, with no need for halide scavengers, ionic liquids, or ionic additives. The use of the hemilabile 1,3-bis(diphenylphosphino)propane monoxide (dpppO) as a ligand led to faster reactions of more challenging 2-substituted vinyl ethers and reduced Pd loadings. In contrast to the related arylation reaction, evidence suggests that the vinylation may proceed via the neutral Heck mechanism.

Direct acylation of aryl bromides with aldehydes by palladium catalysis.

A new protocol for the direct acylation of aryl bromides with aldehydes is established. It appears to involve palladium-amine cooperative catalysis, affording synthetically important alkyl aryl ketones in moderate to excellent yields in a straightforward manner, and broadening the scope of metal-catalyzed coupling reactions.