Stereoselective Olefin Ring‐Opening Cross Metathesis Catalyzed by Molybdenum Imido Alkylidene N‐Heterocyclic Carbene Complexes

摘要: The influence of the structure cationic molybdenum imido alkylidene N-heterocyclic carbene (NHC) catalysts, i. e. [Mo(N-2-tert-butyl-C6H4) (CHCMe2Ph)(NHC)X+ B(ArF)4 ] (NHC=1,3-di(2-Pr) imidazol-2-ylidene (iPr), 1,3-dimesitylimidazol-2-ylidene (IMes); X=pyrrolide, OCH(CF3)2, = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) and [Mo(N-3,5-Me2-C6H3)(CHCMe2Ph)(NHC)(CH3CN)X+ (NHC=1,3-dimesitylimidazol-2-ylidene, 1,3-dimesitylimidazolin-2-ylidene (IMesH2); X=CF3SO3, OCPh(CF3)2) on E/Z-selectivity in ring-opening cross-metathesis (ROCM) endo, endo-2,3- dicarbomethoxynorborn-5-ene (endo, endo-DCMNBE), exo, exo-2,3-dicarbomethoxynorborn-5-ene (exo, exo- DCMNBE), ((+) DCMNBE) 2,3-exo,exo-bis(acetoxymethyl)- 7-oxabicyclo[2.2.l]hept-5-ene (7-oxa-NBE) with 1-pentene, styrene, allyltrimethylsilane, allyl benzyl ether, phenyl ether ethyl has been studied. With exception ROCM reaction endo-DCMNBE all other reactions proceeded under thermodynamic control without any post-metathesis isomerization full retention configuration newly formed 1,2-disubstituted double bond as confirmed by kinetic studies. Similar accounts for selected homometathesis reactions. Catalyst structure-selectivity correlations based buried volume, Vbur, N-imido ligand are presented. All primary data files processed journal article from Buchmeiser group.