Synthesis of pyrano[2,3-: F] chromen-2-ones vs. pyrano[3,2-g] chromen-2-ones through site controlled gold-catalyzed annulations
Regioselective access to 10-substituted-2H,8H-pyrano[2,3-f]chromen-2-ones through the gold-catalyzed intramolecular hydroarylation of readily available 7-(prop-2-yn-1-yloxy)-2H-chromen-2-one derivatives at their C-8 congested position was investigated by tuning the electronic and steric properties of the ligand on the gold complex.