Abstract Bakkenolide A 1 is the simplest member of a new class of eremophilane sesquiterpenes isolated a few years ago from Petasites japonicus. 2 A recent synthesis of 1 3 prompts us to disclose our preliminary results which, in a model system, provide an alternative approach to the construction of the novel β-methylene-γ-spirolactone system present in the bakkenolide series.
