The cybrodins, a new class of sesquiterpenes

Abstract

The isolation and structure determination of the "cybrodins", a new group of sesquiterpenoids produced by a new strain of the bird's nest fungus Cyathus bulleri, is reported. Cybrodol (3), isocybrodol (4), cybrodal (5), trisnorcybrodolide (6), and cybrodic acid (7) may be classified as seco-illudalane sesquiterpenes. The evidence leading to the structural assignments is presented, along with chemical correlations among the cybrodins. The possible mode of biogenesis is discussed. Pterosin-C (13), a known norsesquiterpene, and 3-methyllumichrome (17) were also isolated. Small quantities of a new sesquiterpenoid, broderol, believed to possess structure 21, were obtained on two occasions.