Molybdenum-based complexes with two aryloxides and a pentafluoroimido ligand: catalysts for efficient Z-selective synthesis of a macrocyclic trisubstituted alkene by ring-closing metathesis.

Abstract

Macrocyclic ring-closing metathesis (RCM) has had an enormous impact on organic chemistry;[i,ii] such influence has been in spite of the absence of reliable stereoselective catalyst-controlled protocols. High stereoselectivity is crucial to applications in complex molecule synthesis: a non-discriminating RCM, often performed late stage in a multi-step route, can be costly (overall yield reduction by ≥50%). We have reported that with Mo- or W-based mono-aryloxide pyrrolide (MAP) complexes, macrocyclic disubstituted Z olefins can be obtained efficiently and stereoselectively.[iii] Another problem, more challenging and strategically distinct, relates to synthesis of macrocyclic trisubstituted alkenes;[ii] re-routing through diyne RCM[iv]/alkyne functionalization is not an attractive option in such instances.