The structure 3,4-dihydroxy-2,4,6,8-tetramethyldec-8-enolide (1) was assigned to a metabolite of Botrytis cinerea, but the spectra of several synthetic analogues had significant differences from that of 1. Examination of the constituents of a B. cinerea mutant that overproduces polyketides gave sufficient quantities of 1, now named cinbotolide, for chemical transformations. These led to a revised γ-butyrolactone structure for the metabolite. This structure has been confirmed by an asymmetric total synthesis, which also established its absolute configuration.