Palladium-Catalyzed Direct Esterification via C-H Bond Activation of Aldehydes.

A concise and highly efficient synthesis method of direct esterification of aldehydes via Pd-catalyzed C-H bond activation of aldehyde group has been developed. The strategy avoids the preoxidation step of aldehyde or use of condensing agents in ester synthesis, which is not only applicable to various alcohols but also suitable for the esterification of phenolics which are usually difficult to be esterified. The methodology has the significant advantages of broad substrate scope, mild reaction conditions, and nonrequirement of additional oxidants.

Palladium-catalyzed and alcohol-enabled transformation to synthesize benzocyclic ketones.

Catalytic carbonyl formation ranks as one of the most important synthetic methodologies. Herein, a highly effective palladium-catalyzed and alcohol-promoted transformation of nitriles to synthesize benzocyclic ketones is described. It provides a straightforward access to potentially valuable indanone compounds in high yields in the presence of alcohol.

Palladium(0)-Catalyzed Methylcyclopropanation of Norbornenes with Vinyl Bromides and Mechanism Study.

An unusual methylcyclopropanation from [2 + 1] cycloadditions of vinyl bromides to norbornenes catalyzed by Pd(OAc)2/PPh3 in the presence of CH3ONa and CH3OH has been established. A methylcyclopropane subunit was installed by a 3-fold domino procedure involving a key protonation course. Preliminary deuterium-labeling studies revealed that the proton came from methyl of CH3OH and also exposed an additional hydrogen/deuterium exchange process.

Palladium-catalyzed [2+1+1] annulation of norbornenes with (Z)-bromostyrenes: synthesis of bismethylenecyclobutanes via twofold C(sp(2))-H bond activation.

The first Pd-catalyzed intermolecular [2+1+1] annulation reaction of (Z)-bromostyrene derivatives and norbornenes has been realized. Bismethylenecyclobutane derivatives were obtained with high yields. The domino coupling reaction involves a double Heck-type coupling process, twofold C(sp(2))-H bond activation and formation of three carbon-carbon bonds.

Palladium(0)-catalyzed methylenecyclopropanation of norbornenes with vinyl bromides.

Highly strained methylenecyclopropane derivatives have been achieved via a novel and efficient Pd(0)-catalyzed domino reaction. The formal [2 + 1] cycloaddition reaction of vinyl bromides to norbornenes involves a Heck-type coupling and a C(sp(2))-H bond activation.

Palladium(0)-catalyzed cyclopropanation of benzyl bromides via C(sp3)-H bond activation.

A novel and highly efficient Pd(0)-catalyzed domino reaction to prepare cyclopropane derivatives has been established. The process involves a Heck-type coupling reaction and a C(sp(3))-H bond activation. Preliminary DFT calculations suggest that a four-membered palladacycle intermediate is involved.