Conformational insights into furo- and thieno[2,3-b]indolines derived from coupling constants and molecular modeling
✍ Scribed by Martha S. Morales-Ríos; Norma F. Santos-Sánchez; Nadia A. Pérez-Rojas; Pedro Joseph-Nathan
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 129 KB
- Volume
- 42
- Category
- Article
- ISSN
- 0749-1581
- DOI
- 10.1002/mrc.1479
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✦ Synopsis
Abstract
The extent to which conformational preferences of fused heterocyclic five‐membered rings change with the nature of the heteroatom (O and S) was investigated in furo‐ (1, 2) and thieno[2,3‐b]indolines (3, 4) by the combined use of ^1^H NMR spectroscopy and density functional theory (DFT) calculations. In contrast to the behavior observed for pyrroloindolines, the furo‐ and thienoindolines exist in solution in only one conformer, with structures in the ^2^E–^2^T~3~ (1,2) and ^2^T~3~–E (3,4) North/West region of the pseudorotational wheel, and with pseudorotation phase angles (P) of 315.8, 311.6, 337.2 and 331.6°, respectively. Copyright © 2004 John Wiley & Sons, Ltd.