Enantioselective synthesis of substituted octalones

Asymmetric synthesis of 3β-angeloyloxy-4β-hydroxyeudesman-8-one, purported sesquiterpene from Pluchea quitoc †

“…A stirred solution of 2-methyl-4-ethylenedioxycyclohexanone 29 (5.40 g, 31.7 mmol), R-(ϩ)-α-methylbenzylamine (15.80 cm 3 , 14.85 g, 122.6 mmol), and toluene-p-sulfonic acid monohydrate (0.089 g, 0.47 mmol) in toluene (100 cm 3 ) was refluxed with removal of water for 3 h, whereupon the solvent and excess amine were removed by distillation under reduced pressure. The residue was dissolved in anhydrous THF (90 cm 3 ) and ethyl vinyl ketone (57.0 cm 3 , 48.2 g, 57.3 mmol) was added.…”