GIAO-HF/DFT calculation of 13C and 15N chemical shifts for studying tautomerism and intramolecular hydrogen bonding in 2,3-disubstituted quinoxalines

✍ Scribed by E. Kleinpeter; L. Hilfert; A. Koch

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 285 KB
• Volume: 13
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/1099-1395(200008)13:8<473::aid-poc260>3.0.co;2-e

✦ Synopsis

Both the 13 C and 15 N chemical shifts of a number of quinoxalines substituted in position 2 with the pelectron excess 2'-benzo [b]furanyl substituent which has in position 3' a hydroxy or amino group could be satisfactorily calculated by the GIAO method on the basis of HF and DFT ab initio structures. Thereby both the presence of the intramolecular hydrogen bond -C2=NÁÁÁH-O-C3'and -C2=NÁÁÁH-NH-C3'-, respectively, strongly dominating the common plane of resonance of the two heterocyclic moieties, and the preferred enol tautomer could be studied in detail.