An approach to lauroxanes by iterative use of Co(2)(CO)(6)-acetylenic complexes. a formal synthesis of (+)-laurencin.

A new approach to lauroxanes by a powerful and highly convergent methodology based on iterative use of Co(2)(CO)(6)-acetylenic complexes is described. The strategy employs an intermolecular Nicholas reaction to form unsaturated branched linear ethers, a ring closing metathesis to obtain the cobalt complex cyclic ethers, and an isomerization promoted by montmorillonite K-10. A short synthesis of cyclic ethers of seven-, eight-, and nine-membered rings is described. Additionally, the methodology is exemplified by the formal synthesis of (+)-laurencin, a red algae metabolite.