title: Novel chiral (salen)Mn(III) complexes containing a calix[4]arene unit in 1,3-alternate conformation as catalysts for enantioselective epoxidation reactions of (Z)-aryl alkenes.
abstract: Two new chiral calix[4]arene-salen ligands 1a,b, based on calix[4]arene platforms in 1,3-alternate conformation, have been prepared by a new general synthetic pathway. Their Mn(III) complexes, 3a,b have shown fairly good efficiency in the asymmetric epoxidation of styrene and substituted styrenes, whereas excellent catalytic activity and selectivity were observed with rigid bicyclic alkenes, namely 1,2-dihydro-naphthalene and substituted 2,2'-dimethyl-chromene. The higher catalytic properties of 3a may be ascribed to the more rigid and inherently chiral structure as proved by molecular modelling, NMR spectroscopy and X-ray data of the similarly structured UO2 complexes 2a,b.
authors.affiliation: Dipartimento di Scienze Chimiche, Università di Catania, viale A. Doria 6, 95125 Catania, Italy.
authors.forename: Carmela
authors.initials: C
authors.lastname: Bonaccorso
authors.forename: Giovanna
authors.initials: G
authors.lastname: Brancatelli
authors.forename: Francesco P
authors.initials: FP
authors.lastname: Ballistreri
authors.forename: Silvano
authors.initials: S
authors.lastname: Geremia
authors.forename: Andrea
authors.initials: A
authors.lastname: Pappalardo
authors.forename: Gaetano A
authors.initials: GA
authors.lastname: Tomaselli
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Toscano
authors.forename: Domenico
authors.initials: D
authors.lastname: Sciotto
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D047250:Calixarenes / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry; D008345:Manganese / Q000737:chemistry*; D008968:Molecular Conformation; D010636:Phenols / Q000737:chemistry*; D013237:Stereoisomerism; D014961:X-Ray Diffraction
chemical_list: D000475:Alkenes; D056831:Coordination Complexes; D004852:Epoxy Compounds; D010636:Phenols; C121325:calix(4)arene; D047250:Calixarenes; D008345:Manganese