1H, 13C and 19F NMR Studies of the Diels-Alder Adduct of p-Fluoranil with Phencyclone. II. Hindered Phenyl Rotations and Anisotropic Effects in a Model Compound for Drugs |
| |
Authors: | Kevin Bynum Robert Rothchild Navroz Shariff |
| |
Affiliation: | 1. The City University of New York, John Jay College of Criminal Justice, Science Department , 445 West 59th Street, New York, NY, 10019-1128;2. The Doctoral Faculty, The Graduate School and University Center , City University of New York |
| |
Abstract: | Abstract The Diels-Alder adduct of phencyclone, compound 1, with p-fluoranil, compound 3, has been prepared in refluxing toluene. The adduct, compound 2, has been examined by 1H, 13C and 19F NMR spectroscopy at 300, 75 and 282 MHz, respectively. At ambient temperature, the unsubstituted bridgehead phenyl groups in adduct 2 are found to exhibit hindered rotation, resulting in slow exchange limit (SEL) 1H NMR spectra. Full aryl proton assignments are made based on 1D and 2D (COSY45) NMR. The 19F NMR (proton coupled) reveals one of the two 19F signals to be a triplet. This resonance collapses to a singlet in the proton decoupled 19F spectrum, implying an unexpected long range 1H-19F coupling. For the 13C NMR spectrum, tentative assignments are presented. Data for compound 2 as a model compound for drugs are discussed in terms of the hindered aryl rotation and evidence of magnetic anisotrppic effects. |
| |
Keywords: | One- and two-dimensional NMR COSY Tetrafluoro-1 4-benzoquinone Stereochemistry Conformations Pharmaceuticals |
|
|