2-Azapinanes: Aza Analogues of the Enantiomeric Pinyl Carbocation Intermediates in Pinene Biosynthesis

The enantiomeric 2-azapinanes, aza analogues of the pinyl carbocation intermediates in pinene biosynthesis, were synthesized from (-)- and (+)-cis-pinonic acids. The individual reactions in the 5-step sequence were Beckmann rearrangement of the pinonic acid oximes(1) cyclization to the N-acetyl lactams, hydrolysis to the NH-lactams, N-methylations, and LiAIH(4) reductions. The anti stereochemistry of the N-methyl groups in the salts with respect to the gem-dimethyl bridge was established by NOE measurements and by X-ray diffraction analysis.