piperidines and cryptopleurine

The asymmetric total syntheses of the representative phenanthroindolizidine and phenanthroquinolizidine alkaloids, (-)-antofine and (-)-cryptopleurine, are described. An efficient synthetic pathway to the key intermediate 12, in enantiomerically pure form, was achieved by using a chiral building block (R)-9 and the Overman rearrangement with a total transfer of chirality. The problem of constructing the pyrrolidine and piperidine rings was successfully addressed, primarily by using a ring-closing metathesis reaction and a cross-metathesis reaction, respectively.

Topics: Alkaloids; Alkylation; Animals; Butanols; Cyclization; Indoles; Molecular Structure; Organotin Compounds; Phenanthrolines; Piperidines; Pyrrolidines; Quinolizines; Stereoisomerism