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Applications of 1H NMR selective and biselective relaxation times to elucidate the configurations and conformations of guinesines in solution

✍ Scribed by Makiko Sugiura; Torei Sai; Momoyo Ichimaru; Atsushi Kato; Narao Takao

Publisher
John Wiley and Sons
Year
1991
Tongue
English
Weight
295 KB
Volume
29
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Both selective (T~1~^S^) and biselective relaxation times (T~1~^BS^) were measured for the sulphur containing alkaloids, guinesine‐A, ‐B and ‐C (Ia, Ib and Ic). Their configurations and conformations were determined using the interproton distances (r~ij~) derived from the cross‐relaxation times (σ~ij~), which were obtained from the observed T~1~^S^ and T~1~^BS^ values. Their configurations are concluded to be 3′,4′‐cis‐2,3′‐erythro (Ia), 3′,4′‐cis‐2,3′‐threo (Ib) and 3′,4′‐trans‐2,3′‐erythro (Ic), which are consistent with the results from x‐ray analyses and ^1^H NOE experiments. The preferred conformations in CDCl~3~ solution are also proposed for these alkaloids.

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