title: Efficient synthesis of enantiomerically pure alpha-alkyl cyclopropanecarbonitrile derivatives from pyrazolines.
abstract: [reaction: see text] Thermolysis of enantiopure sulfonyl pyrazolines 4 and 5, easily obtained from (Z)-3-p-tolylsulfinylacrylonitriles (1), afforded sulfonyl cyclopropanes (6, 7) in a completely stereoselective manner in almost quantitative yields. Both cyclopropanes and alkylidenecyclopropanes, containing one or two chiral carbon atoms, one of them being quaternary, were obtained by hydrogenolysis of the C-S bonding and under the conditions reported by Julia, respectively. The highly stereoselective extrusion of nitrogen suggests a concerted mechanism.
authors.affiliation: Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049-Madrid, Spain. joseluis.garcia.ruano@uam.es
authors.forename: José L
authors.initials: JL
authors.lastname: García Ruano
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Alonso de Diego
authors.forename: M Rosario
authors.initials: MR
authors.lastname: Martín
authors.forename: Esther
authors.initials: E
authors.lastname: Torrente
authors.forename: Ana M
authors.initials: AM
authors.lastname: Martín Castro
mesh_terms: D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D009570:Nitriles / Q000138:chemical synthesis* / Q000737:chemistry; D011720:Pyrazoles / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D003521:Cyclopropanes; D009570:Nitriles; D011720:Pyrazoles; C510307:cyclopropanecarbonitrile