Über Pterinchemie 67. Mitteilung Zum Verlauf der katalytischen Reduktion von 6, 7‐Diphenylpterin

On the pathway of the catalytic reduction of 6,7‐diphenylpterin The pathway of the hydrogen addition to the pyrazine ring of 6, 7‐diphenylpterin ( 1a ) during acid‐catalyzed reduction was elucidated. Initial hydrogenation of the 5, 6‐double bond produces 6, 7‐diphenyl‐5, 6‐dihydropterin ( 2a ); this then undergoes a [1, 2]‐H‐rearrangement, which yields the thermodynamically more stable 6, 7‐diphenyl‐7, 8‐dihydropterin ( 3a ). Subsequent reduction of 3a gives 4 .