Graduate School of Science and Technology,a and Faculty of Engineering,b ... Niigata University, 8050, 2 no-cho, Ikarashi, Niigata 950-2181, Japan ... Abstract–Methylenebis(4-hydroxy -2-pyrone) or methylenebis(4-hydroxy- coumarin) derivatives (5) have been synthesized from 4-hydroxy-2-pyrones or 4- hydroxycoumarin (3) with aldehydes (4) by organic solid state reaction. ... The methylene bridged biscoumarins namely dicoumarol (1) and coumetarol ...