Molybdenum imido alkylidene metathesis catalysts that contain electron-withdrawing biphenolates or binaphtholates

摘要

We have prepared new Mo(NR)(CHCMe2Ph)(diolate) complexes (R = 2,6-i-Pr2C6H3, 2,6-Me2C6H3, 1-adamantyl, or 2-CF3C6H4) that contain relatively electron-withdrawing binaphtholate (3,3'-bis(9-anthracenyl), 3,3'-bispentafluorophenyl, or 3,3'-bis(3,5-bis(trifluoromethyl)phenyl)) or biphenolate (3,3'-di-tert-butyl-5,5'-bistrifluoromethyl-6,6'-dimethyl-1,1'-biphenyl-2,2'-diolate) ligands. We also have prepared new monomeric Mo(NR)(CHCMe2Ph)(2,5-dimethylpyrrolide)(2) complexes and have treated them with biphenols or binaphthols in order to prepare several Mo(NR)(CHCMe2Ph)(diolate) species. In one case the new Mo(NR)(CHCMe2Ph)(diolate) complexes could be prepared only through reaction of a binaphthol [3,3'-bis(pentafluorophenyl)binaphthol] with a bis(2,5-dimethylpyrrolide) complex. The pyrrolide approach can be employed either to isolate catalysts on a preparative scale or to generate catalysts in situ. Several simple preliminary ring-closing metathesis reactions show that the new complexes are catalytically competent.