title: Turning Cucurbit[8]uril into a Supramolecular Nanoreactor for Asymmetric Catalysis.
abstract: Chiral macromolecules have been widely used as synthetic pockets to mimic natural enzymes and promote asymmetric reactions. An achiral host, cucurbit[8]uril (CB[8]), was used for an asymmetric Lewis acid catalyzed Diels-Alder reaction. We achieved a remarkable increase in enantioselectivity and a large rate acceleration in the presence of the nanoreactor by using an amino acid as the chiral source. Mechanistic and computational studies revealed that both the amino acid-Cu(2+) complex and the dienophile substrate are included inside the macrocyclic host cavity, suggesting that contiguity and conformational constraints are fundamental to the catalytic process and rate enhancement. These results pave the way towards new studies on asymmetric reactions catalyzed in confined achiral cavities.
authors.affiliation: Department of Polymer Chemistry, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands).
authors.forename: Lifei
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Melville Laboratory for Polymer Synthesis, Department of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW (UK).
authors.forename: Silvia
authors.initials: S
authors.lastname: Sonzini
authors.affiliation: Department of Polymer Chemistry, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands).
authors.forename: Masyitha
authors.initials: M
authors.lastname: Ambarwati
authors.affiliation: Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London SE1 1DB (UK).
authors.forename: Edina
authors.initials: E
authors.lastname: Rosta
authors.affiliation: Melville Laboratory for Polymer Synthesis, Department of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW (UK). oas23@cam.ac.uk.
authors.forename: Oren A
authors.initials: OA
authors.lastname: Scherman
authors.affiliation: Department of Polymer Chemistry, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (The Netherlands). a.herrmann@rug.nl.
authors.forename: Andreas
authors.initials: A
authors.lastname: Herrmann
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D001952:Bridged-Ring Compounds / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D015394:Molecular Structure; D049329:Nanostructures / Q000737:chemistry*; D013237:Stereoisomerism; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
chemical_list: D000596:Amino Acids; D001952:Bridged-Ring Compounds; D003300:Copper; D007093:Imidazoles; D046911:Macromolecular Substances; C507198:cucurbit(8)uril; D047028:Macrocyclic Compounds; D000099246:Cucurbit(n)urils
keywords: Diels-Alder reaction; asymmetric catalysis; host-guest systems; macrocycles; supramolecular chemistry