Unusual open chain quinolinyl peroxol and its alcohol counterpart obtained through a modified Skraup Doebner Von Miller quinoline synthesis: theoretical studies and complete 1H and 13C NMR assignments
Because of their extreme instability, it is generally difficult to synthesize and fully characterize open chain peroxides, also known as peroxols. In our attempt to investigate the mechanism of the Skraup Doebner Von Miller quinoline synthesis, we were able to obtain an unusual open chain peroxy quinoline, namely, 4 (8 ethoxy 2,3 dihydro 1H cyclopenta[c]quinolin 4 yl)butane 1 peroxol (1) and its alcohol counterpart, namely 4 (8 ethoxy 2,3 dihydro 1H cyclopenta[c]quinolin 4 yl)butan 1 ol (2) obtained as a side product during the same reaction. Although structurally similar, these two compounds appeared to display some very distinct physical and spectroscopic characteristics. This work reports detailed NMR studies and full 1H and 13 C NMR assignments for these two compounds. These assignments are based upon the analysis of the NMR spectra of these compounds including 1H, 13 C, COSY, gHSQC and gHMBC. The effect of the peroxide functional group on the chemical shift of neighboring carbons and protons was also investigated by comparing the NMR data of these two compounds. Furthermore, the effects of potential hydrogen bondings in 1, 2, and possible 1 1 dimer, 2 2 dimer and in prototypical model systems, as well as the stability of these compounds, were investigated computationally. The computed dissociation energies and NMR data support the interpretation of the experimental data. Copyright (c) 2012 John Wiley Sons, Ltd.
Magnetic resonance in chemistry MRC