Eremophilane sesquiterpenes from Senecio aureus

Three eremophilane sesquiterpenes have been isolated from Senecio aureus. trans-9-Oxofuranoeremophilane (1) has been previously isolated as a minor constituent of Petasites hybridus, while 8α-ethoxy-10αH-eremophilenolide (5) has not been previously reported. The structure of 3α-angeloyloxy-9-oxo-10αH-furanoeremophilane (7) was firmly established by a single crystal X-ray analysis and its spectral properties are consistent with the assigned structure. The previously reported spectral properties of 3α-angeloyloxy-9-oxo-10αH-furanoeremophilane are inconsistent with its structure.