2,5-Disubstituted
tetrahydrofurans constitute the core skeleton of several natural products and are pivotal synthetic analogues of medicinal importance that exhibit remarkable bioactivities. Oxasqualenoid natural products are implicated as potent biologically active molecules, particularly with regard to demonstrating significant cytotoxicity. Characteristic features of oxasqualenoids containing
tetrahydrofuran fragments include the presence of a cis- and/or trans-2,5-disubstituted pattern in
tetrahydrofuran moieties, and molecular symmetry is often noticed as well. Given their unique structural features combined with their bioactivity, two representative examples from this class of natural products,
eurylene and
teurilene, have been briefly reviewed.
Eurylene, with reported cytotoxicity against
lymphocytic leukemia, contains two non-adjacent linked cis- and trans-2,5-disubstituted
tetrahydrofuran rings and a combined total of eight stereogenic centres. It is a chiral molecule due to the lack of a C2 axis of symmetry.
Teurilene shows a prominent cytotoxicity on KB cells and has three adjacently linked 2,5-disubstituted
tetrahydrofurans. A distinctive achiral facet is observed in
teurilene, despite having eight stereocentres, due to the presence of meso symmetry (Cs). The prime objective of this account is to describe a precise mechanistic insight for both cis- and trans-2,5-disubstituted
tetrahydrofurans present in these natural products and to highlight the exciting challenges encountered during the installation of functionalities or structural motifs en route to their synthetic approaches.