Group Exchange between Ketones and Carboxylic Acids through Directing Group Assisted Rh-Catalyzed Reorganization of Carbon Skeletons.

The Rh(I)-catalyzed direct reorganization of organic frameworks and group exchanges between carboxylic acids and aryl ketones was developed with the assistance of directing group. Biaryls, alkenylarenes, and alkylarenes were produced in high efficiency from aryl ketones and the corresponding carboxylic acids by releasing the other molecule of carboxylic acids and carbon monoxide. A wide range of functional groups were well compatible.

Rh-catalyzed C-C cleavage of benzyl/allylic alcohols to produce benzyl/allylic amines or other alcohols by nucleophilic addition of intermediate rhodacycles to aldehydes and imines.

We report three transformations: 1) direct transformation from biarylmethanols into biarylmethylamines; 2) direct transformation from one biarylmethanol into another biarylmethanol; 3) direct transformation from allylic alcohols into allylic amines. These transformations are based on pyridyl-directed Rh-catalyzed C-C bond cleavage of secondary alcohols and subsequent addition to C=X (X = N or O) double bonds. The reaction conditions are simple and no additive is required.

Reductive cleavage of the Csp2-Csp3 bond of secondary benzyl alcohols: rhodium catalysis directed by N-containing groups.

Cutting loose: 1,1-Biarylmethanol substrates undergo reductive cleavage of the C-C bond in the presence of a cationic Rh(III) catalyst and H(2) (see scheme; DG=directing group). Various functional groups are tolerated in the reaction system. Preliminary studies indicate that a five-membered rhodacycle intermediate, which then converts into a Rh(III) hydride species for the reduction, is involved in the catalytic cycle.

Extrusion of CO from aryl ketones: rhodium(I)-catalyzed C-C bond cleavage directed by a pyridine group.

Snipping tool: the rhodium(I)-catalyzed extrusion of carbon monoxide from biaryl ketones and alkyl/alkenyl aryl ketones was developed to produce biaryls and alkyl/alkenyl arenes, respectively, in high yields. A wide range of functionalities are tolerated. Not only does this method provide an alternative pathway to construct useful scaffolds, but also offers a new strategy for C-C bond activation.