Ritter reaction on terpenoids. III. Stereospecific preparation of bicyclic [3.3.1] substituted piperidines☆

Abstract Treatment of chiral monoterpenes with different nitrile compounds in the presence of perchloric acid affords (1S,5R,8R) 8-alkyl(aryl)-2-alkyl(aryl)-2,4,4,8-tetramethyl-3-azabicyclo[3.3.1]non-2-ene or the corresponding (1R,5S,8S) enantiomer. The respective free imines yield optically pure piperidine derivatives when treated with reducing agents (NaBH 4 , NaCNBH 3 ).