One-carbon bridge stereocontrol in robinson annulations leading to bicyclo[3.3.1]nonanes.
The one-carbon bridge stereochemistry of bicyclo[3.3.1]nonane products formed in the Robinson annulation reactions of 2-substituted cyclohex-2-enones was investigated. In contrast to previous reports, it was found that the major diastereomer formed places the one-carbon bridge substituent anti to the beta-keto ester/amide unit introduced in the Robinson annulation. This stereoselectivity appears to be kinetically controlled. In the case of a beta-keto amide product derived from carvone, it was demonstrated, through base-catalyzed epimerization, that thermodynamic control favors the syn isomer.
Wang
Dong
D
Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
Crowe
William E
WE
D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D003512:Cyclohexanones / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
D001643:Bridged Bicyclo Compounds; D003512:Cyclohexanones; C458301:bicyclo(3.3.1)nonane; D002244:Carbon