Über Pterinchemie. 49. Mitteilung. Eine neue Synthese von 5‐Formyl‐6, 7‐dimethyl‐5,6,7,8‐tetrahydropterin und 5,6,7‐Trimethyl‐5,6,7,8‐tetrahydropterin

Starting with 5‐formyl‐6,7‐dimethyl‐5,6,7,8‐tetrahydropterine (II), a new synthesis of 5,6,7‐trimethyl‐5,6,7,8‐tetrahydropterine (III) is described. Thereby the chemical behaviour of the 5‐formyl group in II is investigated, in order to enable the unequivocal differentiation between formylation at position 5 and at position 10 in folic and tetrahydrofolic acid derivatives. 13C‐NMR. spectra of II and III are discussed.