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 P 1 , with unit cell dimensions a = 7.171, b = 7.255, c = 12.369 Å, α = 100.64, β = 93.32, γ = 98.27°. The tetrahydropyrazine ring exists in a distinctly flattened conformation. The C(13)‐ and C(14)‐CH 3 ‐groups possess a cis ‐configuration with axial position for C(13)‐CH 3 and equatorial for C(14)‐CH 3 . The carbonyl‐group of the N‐formyl function has an ( E )‐configuration.