Pteridines. Part C. Structure and nonenzymatic synthesis of aurodrosopterin

Abstract

Abstract The nonenzymatic synthesis of aurodrosopterin ( 5 ) from 6‐acetyl‐2‐amino‐3, 7, 8, 9‐tetrahydro‐4 H ‐pyrimido‐[4,5‐ b ][1,4]diazepin‐4‐one ( 3 ) and 7,8‐dihydrolumazine ( 4 ) at pH 3 (HCl) was performed. The identity of the synthesized compound with the natural eye pigment isolated from drosophila heads was confirmed by thin‐layer chromatography on cellulose and by comparisons of the 1 H‐NMR and UV/VIS spectra. The nonenzymatic synthesis of a neodrosopterin‐like red pigment from 3 and 2,4‐diamino‐7,8‐dihydropteridine was also carried out, but its identity could not be established. This pigment, called aminodrosopterin, has an absorption peak at 489 nm, which is very close to that of neodrosopterin.