HYDROACYLATION · Rhodium-catalyzed alkene and alkyne hydroacylation
FP7 — People (Marie Curie Actions)
- Duration
- 2013-10-15 → 2015-10-14
- EU contribution
- €221,606
- Participants
- 1
- Scheme
- MC-IEF
Lines connect the coordinator with its partners.
Results in brief
Rhodium-catalyzed alkene and alkyne hydroacylation
The hydroacylation reaction (HA) is a potentially powerful transformation in organic synthesis. The transformation of an aldehyde and an unsaturated hydrocarbon into a ketone involves C-H activation with C-C bond formation under atom-economical conditions. The main limitation of this reaction is the possible decarbonylation of one of the reaction intermediates. The most common catalysts for these processes are rhodium diphosphine complexes. The research proposal aimed the control of the undesirable decarbonylation pathway achiving by both attenuating decarbonylation and promoting the (rate limiting) reductive elimination step of the final product. The previous works in the host group demonstrated that hemilable ligands attenuate the decarbonylation and also complexes bearing small bite angle accelerated the main reaction. Combining these two antecedents, we have synthesized a new family of rhodium complexes containing hemilabile small bite-angle diphosphine ligands (4th generation Weller-Willis catalyst). The new rhodium complexes were excellent catalyst for the intermolecular hydroacylation of a wide variety of inactivated alkene with β-substituted aldehydes. They were remarkably resistant to decarbonylation, allowing substrate recharged without loss in conversion. A detailed mechanistic study (rate, order and labelling studies) allowed us to understand the reaction mechanism and the reasons behind the high activity and selectivity of these catalysts. The most used diphosphine ligands were changed by the novel NHCP ligand, both can show small bite angle when they are coordinated to the metal centre. The novel complexes showed to be active and selective for the intermolecular hydroacylation of alkynes with β-substituted aldehydes. Until the date and according to our knowledge there is any study of metal-mediated catalysed reactions employing this class of NHCP complexes.
Data: CORDIS, © European Union
Project objective
The hydroacylation reaction (HA) is a potentially powerful transformation in organic synthesis. The transformation of an aldehyde and an unsaturated hydrocarbon into a ketone involves the formation of a new C-C bond under atom-economical conditions. The main limitation of this reaction is the possible decarbonylation of one of the reaction intermediates. This research proposal aims the control of this undesirable decarbonylation pathway. This will be achieved by both attenuating decarbonylation and promoting the (rate limiting) reductive elimination step of the final product. With this in mind and taking into account the results recently reported by the host laboratory in the HA field (J. Am. Chem. Soc., 2012, 134, 4885), a new generation of Rh(I) complexes containing small bite angle diphosphine ligands will be employed.The preparation of a series of small bite angle PXP ligands (X being C, N or B) would allow the study of the effect of the different steric and electronic parameters on the catalytic performance of the Rh(I) complexes. Metal complexes bearing phosphine ligands with different R groups (iPr, tBu, Cy, Ph, etc.), hemilabile phosphine ligands and ligands with suitable hydrophilic functionalities (water-soluble R groups) will be screened under the standard “challenging” HA conditions.This project will deliver the synthesis of a set general intermolecular HA catalysts that demonstrate high levels of functional group tolerance, stability under catalytic conditions, attractive rates of reaction for demanding substrates, low catalyst loadings with use of minimal and green solvents. By achieving this, we believe that HA will become a general and robust synthetic method for the production of fine and bulk chemicals, new materials and target molecules, rivaling the process of metathesis, hydrogenation, C–C cross coupling and alkene oxidation that are primary disconnections in organic synthetic methodology.
Original text from CORDIS.
Participants
- THE CHANCELLOR, MASTERS AND SCHOLARS OF THE UNIVERSITY OF OXFORD · OxfordCoordinatorUnited Kingdom
Links
Data: CORDIS, © European Union