Synthesis of all isomers of pulcherrimine, a bitter principle in the sea urchin ovary

All eight isomers of pulcherrimine, a bitter principle of the sea urchin (Hemicentrotus pulcherrimus) ovary have been synthesized, which led to revision of the absolute stereochemistry of pulcherrimine. The synthetic pulcherrimine and the 2S isomer were highly bitter at a concentration of 1.0 mM.