One-pot synthesis of furocoumarins via sequential Pd/Cu-catalyzed alkynylation and intramolecular hydroalkoxylation

A novel and rapid assembly of an interesting class of furocoumarins-4H-furo[3,2-c]chromen-4-ones has been successfully achieved using one-pot sequential coupling/cyclization strategy with easily available starting materials 3-bromo-4-acetoxycoumarins and terminal alkynes. The key synthesis involves Pd/Cu-catalyzed alkynylation with in situ prepared dialkynylzincs followed by intramolecular hydroalkoxylation.