Organic Letters 2007-04-12

Highly efficient ruthenium catalysts for the formation of tetrasubstituted olefins via ring-closing metathesis.

Ian C Stewart, Thay Ung, Alexandre A Pletnev, Jacob M Berlin, Robert H Grubbs, Yann Schrodi

Index: Org. Lett. 9 , 1589, (2007)

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Abstract

[reaction: see text] A series of ruthenium-based metathesis catalysts with N-heterocyclic carbene (NHC) ligands have been prepared in which the N-aryl groups have been changed from mesityl to mono-ortho-substituted phenyl (e.g., tolyl). These new catalysts offer an exceptional increase in activity for the formation of tetrasubstituted olefins via ring-closing metathesis (RCM), while maintaining high levels of activity in ring-closing metathesis (RCM) reactions that generate di- and trisubstituted olefins.