Assymetric syntheses of the ladybug alkaloid adaline and 1-methyl-9-azabicyclo [3.3.1]nonan-3-one

The double Michael addition of benzylamine to 3-alkyl-2,7-cyclooctadienones, followed by hydrogenolysis, affords bridgehead substituted 9-azabicyclo3.3.1]nonan-3-ones. Use of (+)-α-methylbenzylamine in the addition leads to mixtures of diastereomeric adducts in unequal amounts. Although the degree of asymmetric induction is low (10–20% ee), the diastereonomers can be easily separated, affording pure enantiomeric forms of the ladybug alkaloid adaline 1 and the Euphorbia alkaloid 3.