Hydroxycarbonylation of Alkenes with Formic Acid Catalyzed by a Rhodium(III) Hydride Diiodide Complex Bearing a Bidentate Phosphine Ligand

Abstract

An improved catalytic system was developed for the Rh complexcatalyzed hydroxycarbonylation of alkenes using formic acid (HCOOH). Ligand screening revealed DPEphos, a bidentate phosphine ligand, to be effective, and the corresponding rhodium(III) hydride diiodide complex, RhHI 2 (CO)(DPEphos) (2), was applied as a catalyst. Complex 2 showed high activity and selectivity in the hydroxycarbonylation of alkenes using HCOOH without any additives and was applicable to a variety of alkene substrates. Analysis of the catalytic cycle using density functional theory calculations was used to elucidate the reaction steps. Initially, an alkyl group was formed by the insertion of an alkene into Rh−H with subsequent acyl group formation via the insertion of a CO ligand, similar to the reaction steps suggested for Rh-catalyzed alkene hydroformylation. The latter part of the catalytic cycle involved the reductive elimination of acyl iodide and subsequent hydrolysis to form a carboxylic acid, analogous to the reaction steps suggested for the synthesis of acetic acid from methanol and CO using a rhodium complex catalyst with hydroiodic acid as an auxiliary catalyst. These results indicate that the iodine atom in complex 2 acts as an auxiliary catalyst during the additive-free hydroxycarbonylation of alkenes using HCOOH.

Direct synthesis of phthalimides via palladium-catalysed double carbonylation of o-dihaloarenes with nitroarenes

“…We therefore investigated the effect of different natural bite angles of the diphosphine ligands varying from 83° to 114°. 21 As we can be seen from Table 1, there was a significant positive correlation between bite angle and reaction yield. Yields improved as the increasing bite angle of the diphosphine ligands increased and nixantphos (114°) gave the desired product in 95% yield (Table 1, entry 19).…”

Direct Access to Carbamates through Palladium‐Catalyzed Carbonylation of Nitroarenes and Siloxanes

“…Moreover, the chelating effect of the diphosphine ligands is crucial to the thermal stability of the palladium intermediate. Therefore, the effect of different natural bite angles of the diphosphine ligands, which ranged from 83° to 114°, [18a] was studied. As shown in Table 1, there is a direct correlation between the bite angle and the yield of the reaction.…”

Pd-Catalyzed Regioselective Hydrocarboxylation of Alkyl Terminal Olefins with Oxalic Acid

“…To circumvent some drawbacks associated with CO gas, efforts have also been made for the development of hydrocarboxylation with nongaseous CO surrogates . For example, we and others , have shown that hydrocarboxylation can be achieved with HCO 2 H under mild conditions assisted with HCO 2 Ar or Ac 2 O. , Readily available oxalic acid could also serve as a potential carbonyl source for the hydrocarboxylation of olefins with a possible distinct reaction mechanism, which could provide new opportunities to regulate the reactivity and selectivity. The hydrocarboxylation of olefins with oxalic acid in the presence of additional CO has been reported …”