1: Dipartimento di Scienza e Tecnologia del Farmaco, Via Giuria 9, 10125 Torino, Italy. 2: Dipartimento di Chimica Organica e Industriale, Via Venezian 21, 20133 Milano, Italy ... ABSTRACT. In the presence of one-electron metal oxidants (CAN, MAH), 4- hydroxycoumarin (1) adds to alkenes to give 2,3-dihydro-4H-fbro[3,2- c][ l]benzopyran-4-ones. ... Over the past few years, considerable attention has been given to the oxidative ... (IV) ammonium nitrate (CAN)4 or ...