title: Endo-selective enyne ring-closing metathesis promoted by stereogenic-at-Mo monoalkoxide and monoaryloxide complexes. Efficient synthesis of cyclic dienes not accessible through reactions with Ru carbenes.
abstract: Stereogenic-at-Mo monoalkoxide and monoaryloxide complexes promote enyne ring-closing metathesis (RCM) reactions, affording the corresponding endo products with high selectivity (typically >98:<2 endo:exo). All catalysts can be prepared and used in situ. Five-, six-, and seven-membered rings are obtained through reactions with enyne substrates that bear all-carbon tethers as well as those that contain heteroatom substituents. The newly developed catalytic protocols complement the related exo-selective Ru-catalyzed processes. In cases where Ru-based complexes deliver exo and endo products nondiscriminately, such as when tetrasubstituted cyclic alkenes are generated, Mo-catalyzed reactions afford the endo product exclusively. The efficiency of synthesis of N- and O-containing endo diene heterocycles can be improved significantly through structural modification of Mo catalysts. The modularity of Mo-based monopyrrolides is thus exploited in the identification of the most effective catalyst variants. Through alteration of O-based monodentate ligands, catalysts have been identified that promote enyne RCM with improved efficiency. The structural attributes of three Mo complexes are elucidated through X-ray crystallography. The first examples of catalytic enantioselective enyne RCM reactions are reported (up to 98:2 enantiomer ratio and >98% endo).
authors: Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
authors: Yeon-Ju
authors: YJ
authors: Lee
authors: Richard R
authors: RR
authors: Schrock
authors: Amir H
authors: AH
authors: Hoveyda
mesh_terms: D000438:Alcohols / Q000737:chemistry*; D000577:Amides / Q000737:chemistry; D002384:Catalysis; D003516:Cycloparaffins / Q000138:chemical synthesis* / Q000737:chemistry; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011758:Pyrroles / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D000438:Alcohols; D000577:Amides; D003516:Cycloparaffins; D009942:Organometallic Compounds; D011108:Polymers; D011758:Pyrroles; D012997:Solvents; C030011:carbene; D012428:Ruthenium; D008982:Molybdenum; D008697:Methane