H. Niwa et al., AN EFFICIENT SYNTHESIS OF RACEMIC NECINE BASES FROM A COMMON INTERMEDIATE, Bulletin of the Chemical Society of Japan, 70(10), 1997, pp. 2541-2543
Necine bases of pyrrolizidine alkaloids, turneforcidine, hastanecine,
and platynecine are synthesized from ethyl xy-2,3,5,6-tetrahydro-1H-py
rrolizine-7-carboxylate in racemic form.