New Chiral Molybdenum Catalysts for Asymmetric Olefin Metathesis that Contain 3,3‘-Disubstituted Octahydrobinaphtholate or 2,6-Dichlorophenylimido Ligands

Optically pure ( R )-5,5‘,6,6‘,7,7‘,8,8‘-octahydro-1,1‘-bi-2-naphthol was derivatized with mesityl and benzhydryl groups in the 3 and 3‘ positions to give R-H 2 Mes 2 Bitet and R-H 2 Benz 2 Bitet, respectively. Addition of R-K 2 Benz 2 Bitet to Mo(NAr)(CHCMe 2 Ph)(OTf) 2 (dme) yielded Mo(NAr)(CHCMe 2 Ph)(R-Benz 2 Bitet)(THF) ( 7 ), while addition of R-K 2 Mes 2 Bitet to Mo(NAr)(CHCMe 2 Ph)(OTf) 2 (dme) in THF gave Mo(NAr)(CHCMe 2 Ph)(R-Mes 2 Bitet)(THF) ( 8 ). Four complexes that contained the 2,6-dichlorophenylimido ligand were prepared by similar procedures, namely, Mo(NAr Cl )(CHCMe 3 )(S-Biphen)(THF) ( 9 ), Mo(NAr Cl )(CHCMe 3 )(R-Trip 2 BINO)(THF) ( 10 ), Mo(NAr Cl )(CHCMe 3 )(R-Mes 2 Bitet)(THF) ( 11 ), and Mo(NAr Cl )(CHCMe 3 )(R-Benz 2 Bitet)(THF) ( 12 ). X-ray studies of 8, 9, and 12 revealed them to be typical distorted trigonal bipyramids with THF and one biphenolate oxygen occupying axial positions. In 9 and 12 the alkylidene orientation was found to be syn, while in 8 the alkylidene orientation was found to be anti . Catalysts 7, 8, 9, 10, 11, and 12 were all efficient in terms of both conversion and % ee for two standard desymmetrization reactions to form dihydrofurans.