Apoverbenone (6,6-dimethylnorpin-3-en-2-one). An investigation into its preparation by dehydrobromination of a sterically hindered bromo-ketone
Abstract
The dehydrobromination of 3-bromo-6,6-dimethylbicyclo[3,1,1]heptan-2-one has been studied. Treatment with lithium bromide and lithium carbonate in dimethyl sulphoxide gave 6,6-dimethylnorpin-3-en-2-one (apoverbenone) in good yield. From (–)-pin-2(10)-ene, optical purity 91%, we obtained (+)-apoverbenone, [α]D+ 319°(c 2.4% in CHCl3).