Rhodium-Catalyzed Reactions of Alcohols for Synthesis of Cyclopentenones, Imines, and Esters

Abstract

Transition-metal catalyzed reactions serves as a fundamental tool in organic synthesis. Homogeneous catalysis, in particular, has significant advantages due to the ease of controlling reactivity and chemoselectivity. Modifying the reactivity with specially designed ligand enables catalysis applicable toward so many organic transformations and when combined with clear mechanistic studies, it can broaden current state of the art of organic synthesis. So researches toward homogeneous catalyst is one of the most essential part in synthetic chemistry.

The major aim for this research was the development selective organic reaction that is catalyzed by rhodium. This reaction utilized alcohol as the source for carbon monoxide and hydride. The contents also covered is the switchable reactivity observed depending on two different ligand. In the case of cyclization reaction using DPEphos, alcohol was oxidized to aldehyde followed by loss of carbon monoxide. The reactions with xantphos in lieu of DPEphos, however, stopped at aldehyde and the intermediate could be utilized to synthesize imines or esters. Reactivity dependency of transition metals toward ligand is a common observation.

Keywords: Rhodium, Alcohol, Ligand, Cycloaddition, Carbonylation, Imination, Esterification, Tishchenko-type reaction, Dehydrogenation