Ring-Closing Alkyne Metathesis (RCAM)

Alkyne metathesis has been a useful tool for C–C bond formation since the discovery of structurally well-defined metal alkylidynes by Schrock and coworkers.³ These complexes have found use in the synthesis of complex natural products and in material science.⁴ The limitations of these catalysts include air- and moisture-sensitivity as well as incompatibilities with substrates that contain donor sites. Fürstner and co-workers have recently developed an air-stable molybdenum catalyst for alkyne metathesis, which proved versatile and compatible with substrates containing donor sites.⁴ The authors also examined the use of this catalyst in the ring-closing cross metathesis (RCAM) of a variety of alkynes in generating various macrocycles in good yields (Scheme 1).