In 2000, Namikoshi et al. reported the isolation and structural elucidation of a novel [5, 6]- bisbenzannulated spiroacetal [1] from the marine fungus Paecilomyces sp.[2] This unique spiro [chroman-2, 1'(3'H)-isobenzofuran] derivative was identified as a potential antimitotic agent (20% inhibition at 50 μm) using an assay screening for microtubule assembly inhibitors and was subsequently named paecilospirone (1).[3]
