Ring-closing metathesis enantioselective

Negishi E, Tan Z (2005) Diastereoselective, Enantioselective, and Regioselective Carbo-alumination Reactions Catalyzed by Zirconocene Derivatives. 8 139-176 Netherton M, Fu GC (2005)Pa]ladium-catalyzed Cross-Coupling Reactions of Unactivated Alkyl Electrophiles with Organometallic Compounds. 14 85-108 Nicolaou KC, King NP, He Y (1998) Ring-Closing Metathesis in the Synthesis of EpothUones and Polyether Natmal Products. 1 73-104 Nishiyama H (2004) Cyclopropanation with Ruthenium Catalysts. 11 81-92 Noels A, Demonceau A, Delaude L (2004) Ruthenium Promoted Catalysed Radical Processes toward Fine Chemistry. 11 155-171... 

Scheme 6/4.29. Enantioselective domino ring-opening/ring-closing metathesis with a Mo-catalyst.

Catalytic Ring-Closing Metathesis and the Development of Enantioselective Processes... 

Catalytic ring-closing metathesis makes available a wide range of cyclic alkenes, thus rendering a number of stereoselective olefin functionalizations practical. The availability of effective metathesis catalysts has also spawned the development of a variety of methods that prepare specially-outfitted diene substrates that can undergo catalytic ring closure. The new metathesis catalysts have already played a pivotal role in a number of enantioselective total syntheses. 

Catalytic olefin metathesis, in only a few years, has risen to be one of the most important and reliable processes in organic synthesis. Recently, several reports by Schrock and Hoveydallsbbond forming transformations efficiently and enan-tioselectively. A recent concise and enantioselective synthesis of exo-brevicomin by Burke utilizes chiral catalyst 91 (Scheme 13) to effect the desymmetriza-tion of 90 through a ring-closing metathesis.11531... 

Hoppe D, Marr F, Bruggemann M (2003) Enantioselective Synthesis by Lithiation Adjacent to Oxygen and Electrophile Incorporation. 5 61-138 Hou Z, Wakatsuki Y (1999) Reactions of Ketones with Low-Valent Lanthanides Isolation and Reactivity of Lanthanide Ketyl and Ketone Dianion Complexes. 2 233-253 Hoveyda AH (1998) Catalytic Ring-Closing Metathesis and the Development of Enantioselective Processes. 1 105-132 Huang M, see Wu GG (2004) 6 1-36... 

Scheme 7.27. Catalytic enantioselective annulations using RCM (ring-closing metathesis).

Furstner succeeded in the synthesis of dactylol using ring-closing metathesis of 9d. Crimmins synthesized enantioselectively diene 9e, and RCM of 9e gave eight-membered ring compound lOe, which is an intermediate for the synthesis of laurencin [Eq. (6.12)] ... 

The catalytic enantioselective ring-closing metathesis of various polyenes affords unsaturated furans, pyrans, and siloxanes efficiently ... 

The application of complexes 22 and 23 in the desymmetrization of triolefins has yielded the ring closing metathesis products in high enan-tioselectivity, and upon replacement of the orffio-methyl groups by the bulkier isopropyl substituents in 23 the selectivity was even further increased (Scheme 17). The origin of enantioselectivity of the reaction has been investigated in a detailed theoretical study [54],... 

Catalyst 36 was also used for the enantioselective synthesis of functionalized tetrahydropyrans, important building blocks in several biologically active molecules (Scheme 29) [78]. The enantioselectivity of such a reaction was significantly improved by using a ruthenium iodide complex 37. This halogen effect has been previously observed in the ring-closing metathesis (vide supra) [52]. 

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