The seven-membered cyclic borane obtained from the reaction of linalyl acetate and thexylborane loses 2,3-dimethylbut-2-ene, and the resulting dialkylborane gives an alcohol on treatment with sodium cyanide, followed by trifluoroacetic anhydride and oxidation. The structure is confirmed by synthesis. The generality of this reaction was investigated but, of the dialkylboranes examined, only 9-borabicyclononane participated in the cyanidation procedure. A simple synthesis of menthone is presented.