Stereocontrolled construction of 3H-furo[3,4-b]chromen-1(9H)-one scaffolds via organocatalyzed Michael addition and the following intramolecular dehydration

An efficient approach for the stereocontrolled construction of 3 H -furo[3,4- b ]chromen-1(9 H )-one skeleton has been successfully developed through a sequential Michael addition/intramolecular dehydration strategy. The Michael addition of tetronic acid to 2-(( E )-2-nitrovinyl)phenols catalyzed by a bifunctional squaramide derived from l - tert -leucine, and the subsequent intramolecular dehydration promoted by concentrated sulfuric acid, proceed smoothly to give the corresponding pharmaceutically valuable 3 H -furo[3,4- b ]chromen-1(9 H )-ones in acceptable yields with 79–97% ee.