title: Designing 'Totem' C2 -Symmetrical Iron Porphyrin Catalysts for Stereoselective Cyclopropanations.
abstract: The catalytic activity of the iron(III) C2 chiral porphyrin Fe(2)(OMe) in alkene cyclopropanation is herein reported. The catalyst promoted the reaction of differently substituted styrenes with diazo derivatives with trans-diastereoselectivities and enantioselectivities up to 99:1 and 87 %, respectively. In addition, high TON and TOF values (up to 10 000 and 120 000 h(-1) , respectively) were observed indicating good activity and stability of the catalyst in optimized experimental conditions. The study of the cyclopropanation reaction revealed that the porphyrin skeleton is composed of two 'totem' parts which were independently responsible for the observed enantio- and diastereoselectivities. To further our research we also investigated the catalytic role of the methoxy axial ligand coordinated to the iron atom. The molecular structure of Fe(2)(OMe) was optimized by DFT calculations which were also employed to achieve a better understanding of the mechanistic details of the carbene transfer reaction.
authors.affiliation: Department of Chemistry, University of Milan, Via C. Golgi 19, 20133, Milan, Italy.
authors.forename: Daniela Maria
authors.initials: DM
authors.lastname: Carminati
authors.affiliation: Department of Chemistry, University of Milan, Via C. Golgi 19, 20133, Milan, Italy.
authors.forename: Daniela
authors.initials: D
authors.lastname: Intrieri
authors.affiliation: Department of Chemistry, University of Milan, Via C. Golgi 19, 20133, Milan, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Caselli
authors.affiliation: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, 263 avenue du Général Leclerc, 35042, Rennes Cedex, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Le Gac
authors.affiliation: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, 263 avenue du Général Leclerc, 35042, Rennes Cedex, France. bernard.boitrel@univ-rennes1.fr.
authors.forename: Bernard
authors.initials: B
authors.lastname: Boitrel
authors.affiliation: Department of Chemistry, University of Pavia, Via Taramelli 12, 27100, Pavia, Italy. lucio.toma@unipv.it.
authors.forename: Lucio
authors.initials: L
authors.lastname: Toma
authors.affiliation: Department of Chemistry, University of Pavia, Via Taramelli 12, 27100, Pavia, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Legnani
authors.affiliation: Department of Chemistry, University of Milan, Via C. Golgi 19, 20133, Milan, Italy. emma.gallo@unimi.it.
authors.forename: Emma
authors.initials: E
authors.lastname: Gallo
keywords: cyclopropanation; density functional calculations; iron; porphyrins; stereoselective reactions