New DBU (1,8-Diazabicyclo[5.4.0]undec-7-ene) Assisted One-Pot Synthesis of 2,8-Disubstituted 4H-1-Benzopyran-4-ones - Riva, Carlo; De Toma, Carlo; Donadel, Leandro; Boi, Carlo; Pennini, Renzo; Motta, Gianni; Leonardi, Amedeo (Synthesis, 1997)