Naturally occurring benzofuran: isolation, structure elucidation and total synthesis of 5-(3-hydroxypropyl)-7-methoxy-2-(3′-methoxy-4′-hydroxyphenyl)-3-benzofurancarbaldehyde, a novel adenosine A1 receptor ligand isolated from Salvia miltiorrhiza Bunge (Danshen) - Yang,Z.; Hon,P.M.; Chui,K.Y.; Xu,Z.L.; Chang,H.M.; Lee,C.M.; Cui,Y.X.; Wong,H.NC.; Poon,C.D.; Fung,B.M. (Tetrahedron Letters, 1991)