Abstract The first total synthesis of the 3, 5-disubstituted indolizidine toad alkaloid 239Q from the known pyrrolidine 1 has been achieved, in seven steps with a 35% overall yield. The relative stereochemistry of natural 239Q was determined unambiguously by comparison of GC-FTIR spectra of synthetic material with the skin extracts of the toad Melanophryniscus cupreuscapularis. The C7 congeners at the 5-position (12 and 13) showed strong ...