An Alkyne-Metathesis-Based Approach to the Synthesis of the Anti-Malarial Macrodiolide Samroiyotmycin†A.

We report the first total synthesis of samroiyotmycin A (1), a C2 -symmetric 20-membered anti-malarial macrodiolide isolated from Streptomyces sp. The convergent synthetic strategy orchestrates bisalkyne fragment-assembly using an unprecedented Schöllkopf-type condensation on a substituted ß-lactone and an ambitious late-stage one-pot alkyne cross metathesis-ring-closing metathesis (ACM-RCAM) reaction. The demanding alkyne metathesis sequence is achieved using the latest generation of molybdenum alkylidynes endowed with a tripodal silanolate ligand framework. Subsequent conversion to the required E-alkenes uses contemporary hydrometallation chemistry catalysed by tetrameric cluster [{Cp*RuCl}4 ].