Journal of the American Chemical Society, Vol.136, No.47, 16493-16496, 2014
Preparation of Macrocyclic Z-Enoates and (E,Z)- or (Z,E)-Dienoates through Catalytic Stereoselective Ring-Closing Metathesis
The first examples of catalyst-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 3.010 mol % of a Mo-based monoaryloxide pyrrolide complex proceed to completion within 26 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.