title: Enantioselective hydroformylation by a Rh-catalyst entrapped in a supramolecular metallocage.
abstract: Regio- and enantioselective hydroformylation of styrenes is attained upon embedding a chiral Rh complex in a nonchiral supramolecular cage formed from coordination-driven self-assembly of macrocyclic dipalladium complexes and tetracarboxylate zinc porphyrins. The resulting supramolecular catalyst converts styrene derivatives into aldehyde products with much higher chiral induction in comparison to the nonencapsulated Rh catalyst. Spectroscopic analysis shows that encapsulation does not change the electronic properties of the catalyst nor its first coordination sphere. Instead, enhanced enantioselectivity is rationalized by the modification of the second coordination sphere occurring upon catalyst inclusion inside the cage, being one of the few examples in achieving an enantioselective outcome via indirect through-space control of the chirality around the catalyst center. This effect resembles those taking place in enzymatic sites, where structural constraints imposed by the enzyme cavity can impart stereoselectivities that cannot be attained in bulk. These results are a showcase for the future development of asymmetric catalysis by using size-tunable supramolecular capsules.
authors: Grup de Química Bioinorgànica i Supramolecular, Institut de Química Computacional i Catàlisi, and Departament de Química, Universitat de Girona. Campus Montilivi , Girona E17071 Catalonia, Spain.
authors: Cristina
authors: C
authors: García-Simón
authors: Rafael
authors: R
authors: Gramage-Doria
authors: Saeed
authors: S
authors: Raoufmoghaddam
authors: Teodor
authors: T
authors: Parella
authors: Miquel
authors: M
authors: Costas
authors: Xavi
authors: X
authors: Ribas
authors: Joost N H
authors: JN
authors: Reek
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000577:Amides / Q000737:chemistry; D002384:Catalysis; D008958:Models, Molecular; D008968:Molecular Conformation; D010756:Phosphoric Acids / Q000737:chemistry; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism; D020058:Styrene / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D000577:Amides; D010756:Phosphoric Acids; D020058:Styrene; C011067:phosphoramidic acid; D012238:Rhodium