Diels–Alder reaction of furanoeremophilan-6β-ol (petasalbin) and its synthetic analogue, 4- hydroxy-4, 5, 6, 7-tetrahydrobenzofuran, was studied using N-ethyl-and N- phenylmaleimides as the dienophiles, affording corresponding adducts as mixtures of stereoisomers. The adduct of petasalbin and maleimide was also obtained when the latter compound was added to a crude extracted solution of Petasites japonicus var. giganteus. ...
