CrCl2-promoted stereospecific and stereoselective alkyl- and silylcyclopropanation of alpha,beta-unsaturated amides.
An efficient chromium-promoted alkyl- or silylcyclopropanation of alpha,beta-unsaturated amides is described. These reactions can be carried out on (E)- or (Z)-alpha,beta-enamides in which the C-C double bond is di-, or trisubstituted. This process takes place with total stereospecificity and the new stereogenic center is generated with high or total stereoselectivity. Some synthetic applications of the obtained silylcyclopropyl amides are also reported. Two mechanisms based on the generation of carbenoid or carbene complexes have been proposed to explain this cyclopropanation reaction.
Concellón
José M
JM
Universidad de Oviedo, Departamento de Química Orgánica e Inorgánica, Oviedo, Spain. jmcg@uniovi.es
Rodríguez-Solla
Humberto
H
Méjica
Carmen
C
Blanco
Elena G
EG
García-Granda
Santiago
S
Rosario Díaz
M
M
D000577:Amides / Q000138:chemical synthesis / Q000737:chemistry*; D002712:Chlorides / Q000737:chemistry*; D017608:Chromium Compounds / Q000737:chemistry*; D003500:Cyclization; D003521:Cyclopropanes / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D012821:Silanes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D000577:Amides; D002712:Chlorides; D017608:Chromium Compounds; D003521:Cyclopropanes; D012821:Silanes; C017133:chromous chloride