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Bull."},{"key":"ref19\/cit19c","doi-asserted-by":"crossref","first-page":"8636","DOI":"10.1016\/j.tet.2012.07.074","volume":"68","author":"Bianchini R.","year":"2012","journal-title":"Tetrahedron"},{"unstructured":"aThe Michael adducts3a\u2013jcan exist in several tautomeric forms in solution. Because of this, broadening of peaks in the1H NMR spectra and disappearance of some carbon signals in the13C NMR spectra were observedfor some of the compounds.","key":"ref20\/cit20a"},{"unstructured":"bThe1H NMR and13C NMR spectra for compound3din CDCl3without DABCO are shown on p S5 in theSupporting Information).","key":"ref20\/cit20b"},{"unstructured":"cCompound3hafter column purification showed a complex1H NMR spectrum, but when the exact ratio of DABCO was added to the same NMR tube, the spectrum was simplified and was easy to interpret. The1H NMR spectrum without DABCO is shown on p S13 in theSupporting Information.","key":"ref20\/cit20c"},{"unstructured":"dThe spectra for the Michael adducts3a\u2013jrecorded in CDCl3in the presence of DABCO (the peaks at 2.6 ppm in the1H NMR spectrum and \u03b4 45\u201346 ppm in the13C NMR spectrum correspond to DABCO) showed good splitting in1H NMR spectrum and distinct13C signals.","key":"ref20\/cit20d"},{"unstructured":"aCompounds4a\u2013jhad very low solubility in DCM and EtOAc, so their spectra were recorded in either DMSO-d6or MeOD.","key":"ref21\/cit21a"},{"unstructured":"bTautomerism is also possible in the fused heterocycles (4a\u2013h,4j,6). 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