Premium
Conformational behavior on 2,2,3‐trisubstituted 1,2,3,4‐tetrahydroquinoline alkaloids, virantmycin, benzastatins, and their congeners, evaluated by semi‐empirical molecular orbital calculations
Author(s) -
Morimoto Yoshiki
Publication year - 1998
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570350203
Subject(s) - conformational isomerism , chemistry , ring flip , ring (chemistry) , molecular orbital , computational chemistry , coupling constant , stereochemistry , molecule , organic chemistry , physics , particle physics
The conformational behaviors on ring inversion between two half‐chair conformers a and b in physiologically active 2,2,3‐trisubstituted 1,2,3,4‐tetrahydroquinoline alkaloids, virantmycin ( 1 ), benzastatin C ( 6 ), benzastatin D ( 7 ), and their congeners 2–5 , which were revealed by their nmr studies have been quantitatively evaluated by semi‐empirical molecular orbital calculations (PM3). The geometries of respective half‐chair conformers a and b in compounds 1–7 were optimized and it was found that their thermodynamic distributions are approximately valid in comparison with the coupling constants observed in their nmr experiments. Furthermore, these calculations estimated the energy barriers for ring inversion in compounds 1–7 in the range of ca . 4.86–11.13 kcal/mol, which were compatible with rapid interconversions between a and b at room temperature.