New synthetic route towards 2,2-dimethylchromene and synthesis of substituted 7-(dimethylpropargyl)chromene

Article abstract of DOI:10.1002/jhet.5570450340

(Chemical Equation Presented) Trifluoromethansufonic acid (TFA) was found a proper reagent for regioselectively ring closure of resorcinol to afford 7-hydroxy-2,2-dimethyl-2,3-dihydrochromen-4-one 3. The propargylation of 3 gave rise to 2,2-dimethyl-7-(2-methylbut-3-yn-2-yloxy)-2,3-dihydrochromen-4-one 4. Condensation of 4 with substituted phenyl or benzyl Grignard reagents afforded substituted phenyl or benzylidene chromenes 6a-d and 4-(substitutedbenzylidene)- 3,4-dihydro chromenes 8a-e, respectively.