α-Diceroptene: A New Dimeric Structure for Isoceroptene

Prolonged UV irradiation of ceroptene yielded substantial quantities of a compound identical with the previously described isoceroptene, a trace constituent isolated from the farinose exudate of Pityrogramma triangularis. The improved MS, ¹H NMR and ¹³C NMR analyses, together with X-ray diffraction, made possible by the availability of synthetic isoceroptene has led to a revision of the originally proposed structure. Isoceroptene is shown to be a novel, centrosymmetrical dimer of ceroptene, and accordingly the more appropriate name, α-diceroptene, is suggested to replace that of isoceroptene. An improved method for the synthesis of ceroptene is also described.