title: Stereospecific cyclopropanation of highly substituted C-C double bonds promoted by CrCl2. Stereoselective synthesis of cyclopropanecarboxamides and cyclopropyl ketones.
abstract: We describe herein a CrCl(2)-promoted cyclopropanation of alpha,beta-unsaturated amides. This reaction can be carried out on (E)- or (Z)-alpha,beta-enamides in which the C-C double bond is di-, tri-, or tetrasubstituted. In all cases the process is completely stereospecific and only a single diastereoisomer is obtained. In addition, cyclopropyl ketones were readily prepared by reaction of the cyclopropanecarboxamides (derived from morpholine) obtained with a range of organolithium compounds. A mechanism has been proposed to explain the cyclopropanation reaction.
authors.affiliation: Departamento de Química OrgAnica e InorgAnica, Facultad de Química, Universidad de Oviedo, JuliAn Clavería 8, 33071 Oviedo, Spain. jmcg@uniovi.es
authors.forename: José M
authors.initials: JM
authors.lastname: Concellón
authors.forename: Humberto
authors.initials: H
authors.lastname: Rodríguez-Solla
authors.forename: Carmen
authors.initials: C
authors.lastname: Méjica
authors.forename: Elena G
authors.initials: EG
authors.lastname: Blanco
mesh_terms: D000577:Amides / Q000138:chemical synthesis*; D002384:Catalysis; D002712:Chlorides / Q000737:chemistry*; D017608:Chromium Compounds / Q000737:chemistry*; D020650:Combinatorial Chemistry Techniques; D003500:Cyclization; D003521:Cyclopropanes / Q000737:chemistry*; D007659:Ketones / Q000138:chemical synthesis*; D015394:Molecular Structure; D009025:Morpholines / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000577:Amides; D002712:Chlorides; D017608:Chromium Compounds; D003521:Cyclopropanes; D007659:Ketones; D009025:Morpholines; C017133:chromous chloride