Quinolizidines. XXI. Syntheses of (.+-.)- and (-)-alancines.

The first total synthesis of the Alangium alkaloid alancine (10) has been achieved in the form of a racemic modification by means of catalytic hydrogenolysis of the tricyclic amino acid (±) -9. Treatment of (±) -10 with aqueous HCl afforded the hydrochloride salt (±) -11. A parallel synthesis starting with (-) -9 gave (-) -alancine [(-) -10] as well as its hydrochloride [(-) -11] in good yields. The synthetic hydrochloride (-) -11 was found to be identical with a sample isolated from Alangium lamarckii THW., indicating that the natural sample, previously considered to be in the free base form [(-) -10], was actually in the hydrochloride form [(-) -11].