Preparation of Macrocyclic Z‑Enoates and (E,Z)- or (Z,E)‑Dienoates through Catalytic Stereoselective Ring-Closing Metathesis

The first examples of c​atalyst-controlled stereo­selective macrocyclic ring-closing metathesis reactions that generate Z-enoates as well as (E,Z)- or (Z,E)-dienoates are disclosed. Reactions promoted by 3.0–10 mol % of a Mo-based mono­aryl­oxide pyrrolide complex proceed to completion within 2–6 h at room temperature. The desired macrocycles are formed in 79:21 to >98:2 Z/E selectivity; stereo­isomerically pure products can be obtained in 43–75% yield after chromatography. Utility is demonstrated by application to a concise formal synthesis of the natural product (+)-aspicilin.