Nitrogen lone-pair delocalization into aromatic rings has been studied for phenothiazine, N-acetylphenothiazine, and related tricyclic systems with a ‘butterfly’ conformation, by using 13C n.m.r. spectroscopy. Pyridazo[4,5-d][1,4]benzothiazines, phenoxazines, acridane, and simple model compounds such as diphenylamine, 2-methylthioaniline, and their corresponding N-acetyl derivatives were examined. The preferred configuration of the N-acetyl group has been determined for CDCl3 and Me2SO solutions. Nitrogen lone-pair delocalization of the N-acetyl group into the aromatic system is strongly hindered for all tricyclic compounds, and greatly reduced for N-acetyldiphenylamine and also for 2-methylthioacetanilide in Me2SO. For this last compound, the decrease of conjugation is due to a solvent-induced change of conformation; for tricyclic systems it is a consequence of the preferred extra-configuration of the N-acetyl group.
13C nuclear magnetic resonance spectroscopy of nitrogen heterocycles. Part 4. intra-extra Configuration of the N-acetyl group in phenothiazine and related systems with a "butterfly" shape / E. Ragg, G. Fronza, R. Mondelli, G. Scapini. - In: JOURNAL OF THE CHEMICAL SOCIETY. PERKIN TRANSACTIONS 2. - ISSN 1472-779X. - :9(1983), pp. 1289-1292.
|Titolo:||13C nuclear magnetic resonance spectroscopy of nitrogen heterocycles. Part 4. intra-extra Configuration of the N-acetyl group in phenothiazine and related systems with a "butterfly" shape|
RAGG, ENZIO MARIA (Primo)
MONDELLI, ROSANNA (Penultimo)
|Parole Chiave:||phenothiazine ;, 13C-NMR ; conformational analysis|
|Settore Scientifico Disciplinare:||Settore CHIM/06 - Chimica Organica|
|Data di pubblicazione:||1983|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1039/p29830001289|
|Appare nelle tipologie:||01 - Articolo su periodico|