Über Pterinchemie. 61. Mitteilung. Die Kristallstruktur von 5‐Formyl‐6,7‐dimethyl‐5,6,7,8‐tetrahydropterin

The crystal structure of 5-formyl-6,7-dimethyl-5,6,7,8-tetrahydropterine The crystal structure of the title compound, a tetrahydropterine, has been determined by X-ray analysis (direct method) and refined with 1579 structure amplitudes to R = 0.054. The crystal system is triclinic, space group P1, with unit cell dimensions a = 7.171, b = 7.255, c = 12.369 A, α = 100.64, β = 93.32, γ = 98.27°. The tetrahydropyrazine ring exists in a distinctly flattened conformation. The C(13)- and C(14)-CH3-groups possess a cis-configuration with axial position for C(13)-CH3 and equatorial for C(14)-CH3. The carbonyl-group of the N-formyl function has an (E)-configuration.