Preparations and Stereochemistries of Ethyl 3α- and 3β-Methyl-9-oxobicyclo (3, 3, 1) nonane-1-carboxylates and Related Compounds

抄録

The Michael condensation of ethyl 2-oxo-5-methylcyclohexanecarboxylate with acrolein proceeded stereospecifically to afford, upon intramolecular Aldol-type cyclization followed by dehydration, ethyl 3β-methyl-9-oxobicyclo (3, 3, 1) non-6-ene-1-carboxylate (IV), which was hydrogenated to 3β-methyl-9-oxobicyclo (3, 3, 1) nonane-1-carboxylate (V). The corresponding 3α-methyl derivative (XIX) was obtained from the Michael adduct of ethyl 2-oxocyclohexanecarboxylate with methacrolein. Configurations and conformations of the compounds prepared were established from the consideration of chemical and NMR evidences.