2-Propenoic acid, 3-(4-hydroxy-5-benzofuranyl)-, .delta.-lactone 2H-Furo[2,3-h]-1-benzopyran-2-one 523-50-2 Angecin Angelicin Angelicin (coumarin derivative) Furo[5',4':7,8]coumarin Isopsoralen NSC404563