AbstractThe long‐known furanoterpenes furospongin‐1 and dihydrofurospongin‐2 were synthesized for the first time using a chiral‐pool‐based route in an effort to secure the previous configurational assignments. The key C‐11 stereogenic centre was taken from D‐mannose, and the C‐13 alkyl centre was installed exploiting the chirality of mannose. Due to deprotonation and/or enolization of the building blocks used, introduction of the furan moieties was problematic, and so some reactions had to be avoided. The trisubstituted alkene was most satisfactorily constructed using a Julia–Kocienski olefination in 1,2‐dimethoxyethane, with the best (E)/(Z) ratio achieved using a secondary sulfone. The synthetic samples not only provided the first unequivocal piece of evidence for the C‐13 configuration of both natural products, but also confirmed the absolute configuration at C‐11 of furospongin‐1.