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Über Pterinchemie. 77. Mitteilung )Das (6 R,S )‐5‐Formyl‐6‐methyl‐5,6,7,8‐tetrahydropterin: Synthese, chemische und physikalisch‐chemische Eigenschaften
Author(s) -
Ganguly Abhoy N.,
Bieri Jost H.,
Viscontini M.
Publication year - 1981
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19810640138
Subject(s) - chemistry , conformational isomerism , dihedral angle , stereochemistry , chemical shift , formylation , methyl group , coupling constant , crystallography , group (periodic table) , hydrogen bond , molecule , organic chemistry , physics , particle physics , catalysis
(6 R,S )‐5‐Formyl‐6‐methyl‐5,6,7,8‐tetrahydropterine: Synthesis, Chemical and Physico‐chemical Properties (6 R, S )‐5‐Formyl‐6‐methyl‐5,6,7,8‐tetrahydropterine ( III ), a model substance for the biologically important 6‐substituted 5‐formyl‐5,6,7,8‐tetrahydropterines, was obtained for the first time by formylation of the corresponding tetrahydropterine with formic acid. Compound III , analogously to the other known 5‐acyltetrahydropterines, exists in solution (except in DMSO) as a mixture of two rotamers IIIa and IIIb . The two H‐C(7) in III have the same chemical shift and the same coupling constant to H‐C(6), giving rise to a A,A',X,C‐system. Conformational analysis of III , based on its 1 H‐NMR,‐spectrum, shows that the methyl group is pseudo‐axial and the formyl group pseudo‐equatorial. Moreover, the H(X)‐C(6) bond lies nearly in the plane bisecting the C(6)‐C(7)‐H(A), C(6)‐C(7)‐H(A') dihedral angle; the C(6) and C(7) lie outside the N(5)‐C(4a)‐C(8a) plane and the tetrahydropyrazine cycle must be extremely strained, according to Dreiding models.