K. Itoh, S. Kishimoto, K. Sagi
Jun 2, 2009
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0
Influential Citations
3
Citations
Journal
Canadian Journal of Chemistry
Abstract
2-Methoxyfuran reacts with β-nitrostyrenes to give Michael adducts. Interestingly, isoxazoline N-oxides were obtained in the reactions with β-nitrostyrenes possessing additional electron-withdrawing groups [COPh (2f) and CO2Et (2g)]. (Z)-Nitrostyrene (2g) gives trans-isoxazoline (4g) and (E)-nitrostyrene (2f) leads to the cis-form product 4f. We have used theoretical methods to investigate the mechanism and to probe the regio- and stereo-selectivity observed in the rearrangement and the Michael reactions. To account for the selectivity observed in these reactions, we examined the Fukui functions and located the transition states (TS) using density functional theory (DFT) calculations at the B3LYP/6–31G* level. The first step involves a nucleophilic attack by the α-carbon atom (C4) of the furan ring on the vinyl C-atom (C5) of the nitrostyrene part to give a zwitterionic intermediate (IN1). Fission of the C–O bond of the furan ring in the intermediate and ring closure via the oxygen atom (endo-O atom) of t...