Application of 1,2,4-triazoline-3,5-diones in the synthesis of the piperazic acids (hexahydropyridazine-3-carboxylic acids)

Abstract

Diels–Alder reactions between penta-2,4-dienoic acid (and substituted analogues) and 4-phenyl-1,2,4-triazoline-3,5-dione (or 1,2,4-triazoline-3,5-dione) give adducts which, after hydrogenation and hydrolysis, yield the piperazic acid residues identified in the hydrolysates of the monamycin series of cyclohexadepsipeptide antibiotics.