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Über Pterinchemie. 69 Mitteilung [1]. Konformationsanalyse von 5,6,7,8‐Tetrahydropteroinsäure und 5,6,7,8‐Tetrahydro‐ L ‐folsäure
Author(s) -
Furrer HansJürg,
Bieri Jost H.,
Viscontini Max
Publication year - 1978
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.19780610743
Subject(s) - diastereomer , chemistry , folic acid , vicinal , stereochemistry , ring (chemistry) , coupling constant , organic chemistry , medicine , physics , particle physics
Conformational analysis of 5,6,7,8‐tetrahydropteroic acid and 5,6,7,8‐tetrahydro‐ L ‐folic acid In the 360‐MHz‐ 1 H‐NMR.‐spectrum of (6 R , S )‐9,9‐dideuterio‐5, 6, 7, 8‐tetrahydropteroic acid (racemic) (XIII) ( AMX ‐System, Fig. 4 ) and (6 R , S )‐9,9‐dideuterio‐5, 6, 7, 8‐tetrahydro‐ L ‐folic acid (diastereomeric) (XVI) the H a –C(6) and H a –C(7) show a vicinal coupling constant of 6,7 Hz and the H a –C(6) and H e –C(7) one of 3,2 Hz. The first coupling constant provides evidence for an approximate trans ‐diaxal arrangement of H a –C(6) and H a –C(7), and the second for a gauche conformation of H a –C(6) and H e –C(7). The tetrahydropyrazine ring in the racemic 5, 6, 7, 8‐tetrahydropteroic acid (III) and in the diastereomeric 5, 6, 7, 8‐tetrahydro‐ L ‐folic acid (XVII) exists therefore in a half‐chair conformation with a pseudoequatorial position of the side chain at C(6) (Fig.5) .