title: Theoretical study on the mechanism of the [2+1] thermal cycloaddition between alkenes and stable singlet (phosphino)(silyl)carbenes.
abstract: The mechanism and the origins of the stereocontrol observed in the reaction between differently substituted alkenes and stable (phosphino)(silyl)carbenes giving cyclopropanes have been studied computationally. These cyclopropanation reactions proceed via asynchronous concerted mechanisms involving early transition structures with a significant charge transfer from the carbene to the alkene moiety. The geometric features of these transition structures preclude a significant overlap between the orbitals required for secondary orbital interactions between the reactants. The stereoselectivity observed experimentally stems from favorable electrostatic and steric interactions between the reactants leading to the stereoisomers in which the phosphanyl and carbonyl or aryl groups are cis to each other.
authors.affiliation: Farmazi Fakultatea, Kimika Organikoa I Saila, Universidad del País Vasco-Euskal Herriko Unibertsitatea, P. K. 450, 01080 Vitoria-Gasteiz, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Lecea
authors.forename: Mirari
authors.initials: M
authors.lastname: Ayerbe
authors.forename: Ana
authors.initials: A
authors.lastname: Arrieta
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Cossío
authors.forename: Vicenç
authors.initials: V
authors.lastname: Branchadell
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Ortuño
authors.forename: Antoine
authors.initials: A
authors.lastname: Baceiredo
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D003198:Computer Simulation; D003500:Cyclization; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D006838:Hydrocarbons / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008956:Models, Chemical; D015394:Molecular Structure; D017646:Organosilicon Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D000475:Alkenes; D003521:Cyclopropanes; D006838:Hydrocarbons; D017646:Organosilicon Compounds; C030011:carbene; D008697:Methane