252. Synthesis and reactions of droso- and isodrosopterin. Pteridines. LIV

The synthesis of the Drosophila pigments droso- and isodrosopterin ( 7 ) from 7.8-dihydropterin ( 3 ) and 2-hydroxy-3-oxobutyric acid ( 4 ) is described. A reaction mechanism is discussed and proven by isotope experiments. Droso- and isodrosopterin form in weak acidic medium in the presence of NH ions two red reaction products each one of which seems to be identical with neodrosopterin.