Abstract
Quaternization of 9a-cyanomethyl- and 9a-ethoxycarbonylmethyl-octahydroquinolizine (VI and XI) with methyl iodide afforded cis (VIIa and XIIa) and trans methiodides (VIIb and XIIb), respectively. On treatment with lithium in liquid ammonia, the methiodides (VIIa, XIIa, and XXIV) gave the ten-membered ring amines (VIII, XIII, and XXV), respectively, in moderate yields, however, the methiodide (XXIX) gave only the demethylated product (XXVIII). And the methiodide (VIIa) yielded also the decyanated amines (IX and X) as the by-products. The formation of the ten-membered ring amines (VIII, XIII, and XXV) was proved to proceed as shown in Chart 5 via the unsaturated ten-membered ring amines (XVII, XVIII, and XXX), which were actually derived from the methiodides (VIIa, XIIa, and XXIV), respectively. On the other hand, treatment of VIIa and XIIa with sodium ethoxide afforded the endocyclic olefinic ring amines (XV and XVI), which were shown to be obtained by isomerization of the initially formed exocyclic olefinic ring amines (XVII and XVIII), respectively.
