Stereospecific cyclopropanation of highly substituted C-C double bonds promoted by CrCl2. Stereoselective synthesis of cyclopropanecarboxamides and cyclopropyl ketones.
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.
Concellón
José M
JM
Departamento de Química OrgAnica e InorgAnica, Facultad de Química, Universidad de Oviedo, JuliAn Clavería 8, 33071 Oviedo, Spain. jmcg@uniovi.es
Rodríguez-Solla
Humberto
H
Méjica
Carmen
C
Blanco
Elena G
EG
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
D000577:Amides; D002712:Chlorides; D017608:Chromium Compounds; D003521:Cyclopropanes; D007659:Ketones; D009025:Morpholines; C017133:chromous chloride