Synthesis of substituted tricyclo[5.3.1.04,9]undecan-2,6-diones

The morpholine enamines of 4-acetyl-4-phenylcyclohexanone 3a, 4-acetyl-4-isopropenylcyclohexanone 3b, 4-acetyl-4-methylcyclohexanone 3c react with acryloyl chloride to give 1-phenyl-4(N-morpholino)tricyclo[5.3.1.04,9]undecan-2,6-dione 9a, 1-isopropenyl-4(N-morpholino)tricyclo[5.3.1.04,9]undecan-2,6-dione 9b, and 1-methyl-4(N-morpholino)tricyclo[5.3.1.04,9]undecan-2,6-dione 9c, respectively, along with the corresponding substituted adamantane-2,4-diones. The morpholine enamine of 4-acetyl-4-benzylcyclohexa-none 3d and pyrrolidine enamine of 4-acetyl-4-phenylcyclohexanone 3a yield the corresponding 1-benzyl-4(N-morpholino)tricyclo[5.3.1.04,9]undecan-2,6-dione 9d and 8(R)-methyl-1-phenyl-4(N-pyrrolidinyl)tricyclo[5.3.1.04,9]undecan-2,6-dione 9e. No substituted adamantane-2,4-diones were formed in any of the latter two reactions.