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Application of 1 H NMR selective and biselective relaxation times. III —conformational analysis of quinidine in solution
Author(s) -
Sai Torei,
Takao Narao,
Sugiura Makiko
Publication year - 1992
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260301103
Subject(s) - chemistry , dihedral angle , quinidine , relaxation (psychology) , crystallography , crystal structure , stereochemistry , molecule , hydrogen bond , organic chemistry , medicine , psychology , social psychology , pharmacology
A relaxation method was applied to quinidine (1) where cross‐relaxations (σ ij ) were obtained by 1 H selective and biselective T 1 measurements and correlation times for molecular reorientation (τ c ) were evaluated from the frequency dependence of the non‐selective T 1. The interproton distances ( r ij ) were estimated using these σ ij and τ c values, and the conformation of 1 was determined by comparing the estimated r ij values with those calculated from the molecular model. The resulting proposed conformation had the following dihedral angles: ∠ C ‐11C‐10C‐3–C‐4 = 150°, ∠ C‐4′C‐9C‐8C‐7 = 50° and ∠ C‐9′C‐4′C‐9C‐8 = 70°. The conformation of the side‐chain (∠ C‐11C‐10C‐3C‐4) is different from the results for the crystal by x‐ray analyses.