Electronic structure and reactivity of 3-acetyl-2-methylbenzo[ b]thiophene: a quantum chemical study.

The electronic structures of 3-acetyl-2-methylbenzothiophene, the cations resulting from its C-protonation at positions 4-7 and O-protonation, and the dications formed upon protonation at positions 4-7 of the O-protonation product were studied by the MNDO, HF/3-21G, and B3LYP/3-21G methods. Analysis of the relative energies of these cations and dications is in line with the earlier authors' data on the predominant reactivity of positions 4 and 6 of the 3-acetyl-2-methylbenzothiophene molecule toward acylation. [ABSTRACT FROM AUTHOR]