Abstract (−)-Dehydrogriseofulvin (I) is converted to the diphenylether derivatives IV or VIII, respectively, by action of a base or an acid. The mechanism of the basic ring opening reaction has been established by use of 14 C labelled methanol. In the case of the epimerisation of griseofulvin (II) under the influence of methylate, however, it is shown that a more complicated mechanism is involved.
