Synthesis of the lactone of (f) - a- (2-hydroxy-4-rnethyl-5-oxocycloheptyl) propionic acid is described, and its identity with one of the degradation products from xanthurnin has been established. ... Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Calcutta-32, India ... IMPORTANT structural variations, well known from the biogenetic standpoint ,3 of the sesquit erpenoid skeleton and particularly of the five-membered ring ...