Synthesis of Quinolizine Derivatives. V. Studies on Diastereoisomer of Ethyl 3-Quinolizidinecarboxylate.

Abstract

Steric configuration of the two diastereoisomers of ethyl 3-quinolizidinecarboxylate (I) was examined and it was proved from following facts that (Ia) (picrate, m.p. 160∼161°) has the A-type and (Ib) (picrate, m.p. 144∼146°) has the B-type orientation. It was shown that (i) quinolizidine ring is in trans type ; (ii) basic isomerization of (I) and (Ia) afforded a fair amount of (Ib) ; and that (iii) reduction of (Ia) and (Ib) with lithium aluminum hydride resulted in their derivation to 3-lupinine (IIa) and 3-epi-lupinine (IIb), respctively. The steric configuration of (IIa) and (IIb) had previously been approximately determined from measurement of their infrared spectra and dipole moment. It was confirmed through preparation of the tosylates of (IIa) and (IIb), and comparison of their chemical properties that (IIa) had an axial -CH₂OH group and (IIb), the equatorial-CH₂OH.