Rhodium-catalyzed one pot synthesis of hydroxymethylated triglycerides†
The direct functionalization of the carbon–carbon double bonds of triglycerides is of major interest to access biosourced building blocks with unique molecular and functional properties. In this study, we described the synthesis of trihydroxylated triglycerides via a hydrohydroxymethylation reaction, which consists of two consecutive Rh-catalyzed reactions, namely, a hydroformylation followed by a consecutive reduction of formyl groups. Contrary to two-step procedures described in the literature, no phosphane was used to coordinate Rh-species, thus giving our strategy an industrial potential. Tertiary amines were used as ligands to promote the hydrohydroxymethylation reaction. The Rh/amine-catalyst proved to be active both in hydroformylation of the carbon–carbon double bond and reduction of the resulting aldehyde into alcohol. The proportion of hydroxyl groups grafted onto triglyceride fatty chains was optimized by a careful choice of experimental conditions, especially the nature and the amount of the tertiary amine, the reaction temperature, and the CO/H2 pressure.