Total synthesis of enantiopure phalarine via a stereospecific Pictet-Spengler reaction: traceless transfer of chirality from L-tryptophan

An appropriately constructed 2-substituted derivative of L-tryptophane undergoes conversion, in a single step, to a prephalarine structure. The reaction occurs in a diastereoselective fashion, leading shortly thereafter to the naturally occurring version of the alkaloid, phalarine.