November, 1971] BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN, VOL. 44, 3165 3167(1971) 3165 The Structure of Petasitolone, a New Constituent of Petasites japonicus Maxim11 Keizo Naya, Fumio Yoshimura, and Ichiro Takagi Department of Chemistry, Faculty of Science, Kwansei Gakuin University, Uegahara, Nishinomiya, Hyogo (Received May 29, 1971) Petasitolone(I), a new sesquiterpene isolated from Petasites japonicus Maxim, has ...