The cyclization of cyclohexane-1,3-diones with various substituted pyridinium salts afforded functionalized 8-oxa-10-aza-tricyclo[188.8.131.52 2,7]trideca-2(7),11-dienes. The reaction proceeds by regioselective attack of the central carbon atom of the 1,3-dicar-bonyl unit to 4-position of the pyridinium salt and subsequent cyclization by base-assisted proton migration and nucleophilic addition of the oxygen atom to the 2-position, as was elucidated by DFT computations. Fairly extensive screening of bases and additives revealed that the presence of potassium cations is essential for formation of the product. © 2013 Kiamehr et al; licensee Beilstein-Institut.
Kiamehr, M., Moghaddam, F. M., Mkrtchyan, S., Semeniuchenko, V., Supe, L., Villinger, A., … Laroshenko, V. O. (2013). Tandem dinucleophilic cyclization of cyclohexane-1,3-diones with pyridinium salts. Beilstein Journal of Organic Chemistry, 9, 1119–1126. https://doi.org/10.3762/bjoc.9.124