Metathesis Reactions - University Of Chicago
Metathesis ReactionsLecture NotesKey Reviews:Olefin MetathesisK. C. Nicolaou, P. Bulger, D. Sarlah, Angew. Chem. Int. Ed. 2005, 44, 4490.T. M. Trnka, R. H. Grubbs, Acc. Chem. Res. 2001, 34, 18.A. Furstner, Angew. Chem. Int. Ed. 2000, 112, 3140.R. H. Grubbs, S. J. Miller, G. C. Fu, Acc. Chem. Res. 1995, 28, 446.Alkyne MetathesisM. Mori, Topics Organomet. Chem. 1998, 1, 133.Enyne MetathesisS. T. Diver, A. J. Geissert, Chem. Rev. 2004, 104, 1317.Metathesis in Complex Molecule SynthesisK.C. Nicolaou, S.A. Snyder, Classics in Total Synthesis II, Chapter 7.
Alkene Metathesis Reactions:Background MaterialR1 [M]R2R1 R2J.-L. Herisson, Y. Chauvin, Makromol. Chem. 1970, 141, 161.
Alkene Metathesis Reactions:Background MaterialR1R1[M] R2R2[M]R1R1R2MMR1R2R1R2[M]R1J.-L. Herisson, Y. Chauvin, Makromol. Chem. 1970, 141, 161.
Alkene Metathesis Reactions:Background MaterialXnXnRCM[M]ROMPROMXnADMETXn[M]nVersions of the olefin metathesis reaction:RCM ring-closing metathesisROM ring-opening metathesisADMET acyclic diene metathesis polymerizationROMP ring-opening metathesis polymerization
Alkene Metathesis Reactions:Background MaterialXnXnRCM[M]ROMPROMXnADMET[M]Xnnnorbornene
Alkene Metathesis Reactions:Background MaterialRCMROMPROM[M]ADMETnnorbornene
Alkene Metathesis Reactions:Background MaterialXnXnRCM[M]ROMPROMXn[M]ADMETXnn
Alkene Metathesis Reactions:Background MaterialRCM[M]ROM[M]
Alkene Metathesis Reactions:Applications in Industrial ProcessesThe Phillips triolefin processMeMe [Mo] MeMeThe Norsorex process[W]ROMnorbornene[W]ROMPnNote: Early industrial processes used weird mixtures of metals to initiate metathesis such asmolybdenum oxide on alumina combined with LiAlH4. They are still used today because theyare both cheap and effective for these particular polymers. In fact, 45,000 tons of the Norsorexnorbornene polymer are produced annually.Phillips Petroleum Company, Hydrocarbon Process, 1967, 46, 232.
Alkene Metathesis Reactions:Background MaterialR1R1[M] R2R2[M]R1R1R2MMR1R2R1R2[M]R1J.-L. Herisson, Y. Chauvin, Makromol. Chem. 1970, 141, 161.
Alkene Metathesis Reactions:What are Effective Initiators for the Process?197519801985199019952000WPhRW(CO)5R Ph orR OMe(Katz, 1976)AcidsAlcohols, WaterAldehydesKetonesOlefinsEsters, AmidesFunctionalgroupreactivity
Alkene Metathesis Reactions:What are Effective Initiators for the MeW(CO)5CpR Ph orR OMe(Katz, 1976)TiCp(Tebbe andParshall, 1978)AcidsAcidsAlcohols, WaterAlcohols, , AmidesEsters, AmidesOlefinsFunctionalgroupreactivity
Alkene Metathesis Reactions:What are Effective Initiators for the Process?19751980W1985CpCpAlCli-PrMeW(CO)5CpR Ph orR OMe(Katz, CO(Tebbe andParshall, 1978)NMoi-PrPhMeMe(Schrock, 1990)AcidsAcidsAcidsAlcohols, WaterAlcohols, WaterAlcohols, insOlefinsEsters, AmidesKetonesEsters, AmidesOlefinsEsters, AmidesFunctionalgroupreactivity
Alkene Metathesis Reactions:What are Effective Initiators for the )5CpR Ph orR OMe(Katz, 1976)1995MeCpPh1990TiCp(F3C)2MeCO(F3C)2MeCO(Tebbe andParshall, 1978)NMoi-PrPhMeMeClPCy3ClRuPhPCy3Ph(Schrock, 1990)(Grubbs, 1992)AcidsAcidsAcidsOlefinsAlcohols, WaterAlcohols, WaterAlcohols, WaterAcidsAldehydesAldehydesAldehydesAlcohols, WaterKetonesKetonesOlefinsAldehydesOlefinsEsters, AmidesKetonesKetonesEsters, AmidesOlefinsEsters, AmidesEsters, AmidesFunctionalgroupreactivity
Alkene Metathesis Reactions:What are Effective Initiators for the Process?MeClPCy3ClRuPCy3PhGrubbs, 1995"a.k.a. Grubbs I"i-Prt-BuMeMeOMoOMet-BuCy NNMe i-PrMePhHoveyda andSchrock, 1998(first asymmetricmetathesis initiator)N CyMeClRuClPhCy NN CyHerrmann, 1998MeMeMeNNClMeRu MeClPhPCy3Grubbs, 1999"a.k.a. Grubbs II"
Alkene Metathesis Reactions:An Initiator "Caught-in-the-Act" of hHOMeThis finding of one displaced PPh3 ligand served as the key discovery leadingto the development of new ligands for ruthenium systems with differentreactivity profiles from the original catalysts.M. L. Snapper and co-workers, J. Am. Chem. Soc. 1997, 119, 7157.
Alkene Metathesis Reactions:What are Effective Initiators for the Process?MeClPCy3ClRuPCy3PhGrubbs, 1995"a.k.a. Grubbs I"i-Prt-BuMeMeOMoOMet-BuCy NNMe i-PrMePhHoveyda andSchrock, 1998(first asymmetricmetathesis initiator)N CyMeClRuClPhCy NN CyHerrmann, 1998MeMeMeNNClMeRu MeClPhPCy3Grubbs, 1999"a.k.a. Grubbs II"Note: For molybdenum systems, attaching more electron-withdrawing ligandsincreases metathesis activity. This trend is true for most late transition-metal initiators.Ruthenium, however, is an exception. Both the Herrmann and "Grubbs II" systems improve upon"Grubbs I" by the attachment of bulky, and strongly basic (σ-donating) phosphine ligands.
Ring-Closing Olefin Metathesis:Applications in SynthesisMeOHHOHHHOHOOTBSOTHF, 25 65 C, 5 hHOHHHHOCpHOBnMeTiCpOBn(4.0 equiv)AlClMeK. C. Nicolaou and co-workers, J. Am. Chem. Soc. 1996, 118, 10335.
Ring-Closing Olefin Metathesis:Applications in SynthesisMeOHOHHHHOHHOOTBSOTHF, 25 65 C, 5 hOHHHOHOHHHHOHTBSORing-closing metathesisMeOHHOHHHOHTBSOOBnHO(4.0 HHHOHOBnOBnK. C. Nicolaou and co-workers, J. Am. Chem. Soc. 1996, 118, 10335.
Ring-Closing Olefin Metathesis:Less Obvious Applications in Total SynthesisClMeOMePCy3ClRuOMeCHOPhPCy3O (15 mol %)MeOOMeCH2Cl2,TBSO40 C, 72 HMeOFBTBSOOMeO MeClA1HOClOMe OMeMeOODMeOBOHONO2OAMeMeOMeO OCOMeMe OMeOOEOOHFOOHOHOHOOOGOOMeOHO OOOSPhOPMBMeA2HOeverninomicin 13,384-1K. C. Nicolaou and co-workers, Angew. Chem. Int. Ed. 1998, 37, 1874.OH
Ring-Closing Olefin Metathesis:Applications in Total SynthesisOAcAcO MeONHCOCF3Me65OAMeC6H6, 60 C,10 h(90%)Ring-closingmetathesisOMe HNMei-PrO(20 mol %)Note: Only the Schrock Mo initiator andthe second generation Grubbs initiator canform tricyclic olefins via RCM.OMe HNMe1. H2, Pd/C(69%)2. N2H4(F3C)2MeCO Mo(F3C)2MeCOOAPhMeMeOHHO MeONH2Mei-PrNOAcAcO MeONHCOCF3OMe HNMeSch38516A. H. Hoveyda and co-workers, J. Am. Chem. Soc. 1997, 119, 10302.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisSHONOOOClPCy3ClRuPCy3HOSPh6 mM in CH2Cl2,25 C, 12 hRing-closing metathesis(100% E-isomer)ONOOIn general, ring-closing metathesis provides predominantly E-alkenes, thoughthe actual distribution is subject to many factors: thermodynamic stability,stereochemistry of the intervening chain, reaction conditions, etc.K. C. Nicolaou and co-workers, Angew. Chem. Int. Ed. Engl. 1996, 35, 2399.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisSHONClPhPCy36 mM in CH2Cl2,SHO25 C, 20 h(85%, 1.2:1 Z:E)Ring-closing metathesisOOPCy3ClRuOTBS ONOOOTBS O(98%)O OOSHONOOOHTFA, CH2Cl2,0 C, 3 hOepothilone AF3CMe ,CH3CN/Na2EDTA(2:1), 0 C, 1 h(75%)(4.8:1.0 ratioof epoxideisomers)SHONOOOHOepothilone CK. C. Nicolaou and co-workers, Angew. Chem. Int. Ed. 1997, 36, 166.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisSHONOOOClPCy3ClRuPCy3HOSPh6 mM in CH2Cl2,25 C, 12 hRing-closing metathesis(100% E-isomer)ONOOIn general, ring-closing metathesis provides predominantly E-alkenes, thoughthe actual distribution is subject to many factors: thermodynamic stability,stereochemistry of the intervening chain, reaction conditions, etc.K. C. Nicolaou and co-workers, Angew. Chem. Int. Ed. Engl. 1996, 35, 2399.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisSchrock catalyst(Danishefsky)or "Grubbs I"(Schinzer)SRONOXYSRONvarious conditionsRing-closing metathesisOOXYOInvestigatorRXYSolventT ( C)t (h)DanishefskyTBSTBSTBSTBSHTBSα-OTPS, β-Hα-OTPS, β-Hα-OTPS, 4Z:E Ratio Yield (%)S. J. Danishefsky and co-workers, J. Am. Chem. Soc. 1997, 119, 2733.D. Schinzer and co-workers, Angew. Chem. Int. Ed. Engl. 1997, 36, 523.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisSSATBSONOOOTBS O(20 mol %)TBSOC6H6, 55 C, 2 h(86%)(1:1 Z:E isomers)Ring-closing metathesisDMDO NOOOTBS O1. HF py2. DMDO, (87% overall)-50 CO OOSi-Pri-PrN(F3C)2MeCO(F3C)2MeCOMoAPhMeMeQuestion: what initiatorsare capable of formingtrisubstituted olefinsvia ring-closing metathesis?HONOOOHOepothilone BS. J. Danishefsky and co-workers, J. Am. Chem. Soc. 1997, 119, 2733.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisOOSSBTBSONOOOTBS O(30 mol %)TBSOCH2Cl2, 45 C, 48 h(89%)(1:1 E:Z isomers)Ring-closing metathesisNOOOTBS O1. H2, Pd/C, EtOH2. TFA, CH2Cl2OClMes NPCy3ClRuPCy3APhN MesClRuClPCy3BSHONOPhOOHOepothilone BJ. Sun, S. C. Sinha, Angew. Chem. Int. Ed. 2002, 41, 1381.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeONHMeOOMeA(13 mol %)CH2Cl2, Δ, 3 h(67%)(8:1, Cy3PhAS. F. Martin and co-workers, J. Am. Chem. Soc. 1999, 121, 866.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeONHMeOOMeA(13 mol %)CH2Cl2, Δ, 3 h(67%)(8:1, Z/E)Ring-closingmetathesisHNOONHClPCy3AMeO1. KOH,MeOH, ΔHNOO2.NHOMeHOHON3OCl(75% overall)NPCy3ClRuOMeNHNHHA (110 mol %), Ring-closingC6H6, Δ, 30 min; metathesisthen HCl (26%)OOHNPhHHNmanzamine AS. F. Martin and co-workers, J. Am. Chem. Soc. 1999, 121, 866.HHNOHO
Ring-Closing Olefin Metathesis in Total Synthesis:Difficulty Predicting E-/Z- Product DistributionMeOMeOMeMeOMeOMeOMeMeMeOMe MeOMep-BrBzOK. C. Nicolaou and co-workers, Angew. Chem. Int. Ed. 2002, 41, 3276.
Ring-Closing Olefin Metathesis in Total Synthesis:Difficulty Predicting E-/Z- Product DistributionMeOMeMeMeOOMeMeOMeMeMeOMe OMeMeOMeMe(48%)CH2Cl2,40 C, 3 h(86%)RCMMeOp-BrBzOAp-BrBzOCH2N2O OMeMeOMe OOp-BrBzMeMeMe(32%)MeOMeOMeOMeMeNMeNCl MeClPhPCy3MeRuAOMep-BrBzOMeMeAMeCH2Cl2,40 C, 3 h(80%)RCMMeO OMeOOp-BrBz OMeNote: Product distribution is kinetically controlled!K. C. Nicolaou and co-workers, Angew. Chem. Int. Ed. 2002, 41, 3276.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeOMeOOOOPhOOOMeOA(5 mol %)OCH2Cl2, 45 3ClRuPCy3MeOHOHOOHOHPhAOMePh OOOOtricolorin AMeOMeOMeOH2, Pd/C,(77%)EtOHOOMeOMeOOOOOHOOOOPhOOA. Furstner, T. Muller, J. Org. Chem. 1998, 3, 424.OOHOOOMe
Facilitating/Hindering Ring-Closing Olefin Metathesis:Long and Short Range ChelationOMLMLgood chelationOORbad chelationK.C. Nicolaou, S.A. Snyder, K.B. Simonsen, A.E. Koumbis, Angew. Chem. Int. Ed. 2000, 39, 3473.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeOMeOOOOPhOOOMeOA(5 mol %)OCH2Cl2, 45 3ClRuPCy3MeOHOHOOHOHPhAOMePh OOOOtricolorin AMeOMeOMeOH2, Pd/C,(77%)EtOHOOMeOMeOOOOOHOOOOPhOOA. Furstner, T. Muller, J. Org. Chem. 1998, 3, 424.OOHOOOMe
Facilitating/Hindering Ring-Closing Olefin Metathesis:Long and Short Range ChelationOMLMOORLgood chelationbad chelationExample of bad chelation:Lewis basic nitrogenNNOOMeOONMeXONMeMeOK.C. Nicolaou, S.A. Snyder, K.B. Simonsen, A.E. Koumbis, Angew. Chem. Int. Ed. 2000, 39, 3473.
Ring-Closing Olefin Metathesis:Applications in Total ne, 100 C2. PPTS(23% overall)Ring-closingmetathesisMeOONHONOSOOH OHgriseoviridinA. I. Meyers and co-workers, Angew. Chem. Int. Ed. 2000, 39, 1664.NH
Cascades of Metathesis Reactions:Applications in Total SynthesisMe MeSiOClPCy3ClRuPhPCy3(5 mol %)CH2Cl2, 25 C, 4 hROM-RCM cascadeTsNMeOMeSiNTs HTBAF, CH2Cl2(78%-78 25 C overall)OHNH H(–)-halosalinOH1. H2, Pd/C2. Na/Hg, MeOH,K2HPO4, Δ(81% overall)NTs HR. Stragies, S. Blechert, Tetrahedron 1999, 55, 8179.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeMeMeMeMeMeMeMeOBnOHO(29 mol %)ClPCy3ClRuPCy3Ph3.8 mM in CH2Cl2,45 C, 42 h(79%, 7:1 E:Z)Ring-closing metathesisMeMeMeMeMeMeMeMeOBnOHOK. Kakinuma and co-workers, J. Org. Chem. 1998, 63, 4741.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeMeMeMeMeMeMeMeOBnOHO(20 mol %)ClPCy3ClRuPCy3Ph108 mM in CH2Cl2, 25 C, 9 h(81% based on recovered s.m.)Cross . Kakinuma and co-workers, J. Org. Chem. 1998, 63, 4741.OBn
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeMeMeMeMeMeMeMeOBnOHO(20 mol %)ClPCy3ClRuPCy3Ph108 mM in CH2Cl2, 25 C, 9 h(81% based on recovered s.m.)Cross metathesisMeMeMeMeMeMeMeMeOBnOOMeMeMeMeMeMeMe1. "Grubbs I" (20 mol %)1.0 mM in CH2Cl2, 45 C, 72 h2. H2, Pd/C, EtOAcRing-closing metathesis(34% eMeK. Kakinuma and co-workers, J. Org. Chem. 1998, 63, 4741.OH
Cross Metathesis: A Reaction With A Slew of Potential ProblemsAA ABBABBAABBBASix possible products; often all are formed.Sometimes, though, cross selectivity can be achieved in certain cases;E-/Z- control is still not as perfect as might be desired.R. H. Grubbs and co-workers, J. Am. Chem. Soc. 2003, 125, 11360
Cross Metathesis: A Reaction With A Slew of Potential ProblemsAA ABBABBAABBBACrossmetathesisproductsSix possible products; often all are formed.Sometimes, though, cross selectivity can be achieved in certain cases;E-/Z- control is still not as perfect as might be desired.R. H. Grubbs and co-workers, J. Am. Chem. Soc. 2003, 125, 11360
The Total Synthesis of LaurefucinOHI2,NaHCO3OHOH OOHOI(42%)trans-3-hexene,Hoveyda-Grubbs III(34%)(78%)OHOMeIwith A. P. Brucks, D. S. Treitler, I. Moga, J. Am. Chem. Soc. 2012, 134, 17714.
The Total Synthesis of LaurefucinOHI2,NaHCO3OHOH OOHOI(42%)trans-3-hexene,Hoveyda-Grubbs III(34%)(78%)OHOMeIwith A. P. Brucks, D. S. Treitler, I. Moga, J. Am. Chem. Soc. 2012, 134, 17714.
Cross Metathesis: A Reaction You Have Seen Before1.OEtOHMgBrOOlefin crossmetathesis(62%)MeCNMeMeNMeClNRuCl Oi-PrAIntramolecularH2NOH HCl, NaOAc, nitrone [3 2]MeOH/MeCN, 50 C cycloadditionMeCNOCNO2. PCC, CH2Cl2(91% ftCNCNCNP. L. Fuchs and co-workers, J. Am. Chem. Soc. 2006, 128, ASAP.D. L. Hughes and co-workers, J. Org. Chem. 2004, 69, 1598.CN
Cross Metathesis:Applications in Total SynthesisOHOMeOMe OMe MeOMeHOHONHMeOMe OMe MeOMeOHOClOMeMeHMeOPCy3ClRuPCy3OMePhCH2Cl2,25 C, 22 h(58%)(1:1 E:Z isomers)Cross OHOOHOHOHHMeOHS. T. Diver, S. L. Schreiber, J. Am. Chem. Soc. 1997, 119, 5106.See also: The Billion Dollar Molecule by Barry WerthOMe OMeOMe
Cross Metathesis:Applications for Generating Potent AntiobioticsHOMeHO OHMeH2NOOHO OOHOH ONOOClHNOOO2CHOOHONHON HClONNH OHNH2H2NMeMeMeOHOHONNH3 HMe HNOOOMeL-Lys-D-Ala-D-AlaVancomycin-susceptible bacteriaD. H. Williams and co-workers, Angew. Chem. Int. Ed. 1999, 38, 1172.
Cross Metathesis:Applications for Generating Potent AntiobioticsHOMeHO OHMeH2NOOHO OOHOH ONOOClHNOON HO2CHOOHOONNH OHNH2OHOHONNH3 HH2NMeMeMeHOH ble bacteriaOHOOO2CNNH OHNH2OHOHOOClNHON HHOMe HNOClNHOOHHOMeHOH2N MeOOHO OLoss of onehydrogen bondleads to a 1000-folddecrease in potencyNNH3 HMeOOOOMeL-Lys-D-Ala-D-LacVancomycin-resistant bacteriaD. H. Williams and co-workers, Angew. Chem. Int. Ed. 1999, 38, 1172.H2NMeMeMe
Cross Metathesis:Applications in Total SynthesisHOMeMeOHO HOHNnOOOOHOHOOONH HOOClHNOHOHNPCy3ClRuClPhPCy3ClOHHNNH HHOO2N RH(20 mol %)vancomycinC15H25NMe3Br (2.2 equiv),dimersH2O/CH2Cl2 ( 95:5),23 C, 24 h(40-75%)Cross metathesisNH2OR1 NHOHOHHOProcess when executed in the presenceof vancomycin's biological target is knownas dynamic combinatorial screening.vancomycin analogsK. C. Nicolaou and co-workers, Chem. Eur. J. 2001, 7, 3824.
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeTESOClMeOOMeMePCy3ClRuMeTESOMePhPCy3(34 mol %)0.1 M in C6H6,1.25 h, 25 C(77%)Cross metathesis/ring-closing metathesisMeOMeOOMeOMeMeOTESMe1. TBAF, THF2. H2, PtO2, EtOHMeMeHOMeHOHOOHOHMeOHHOPhSH, K2CO3215 C,MeOsealed tube(60% overall) MeMeMeOOMeOMeMe(–)-cylindrocyclophane AA. B. Smith and co-workers, J. Am. Chem. Soc. 2001, 123, 5925.OHMe
Ring-Closing Olefin Metathesis:Applications in Total SynthesisMeMeClPCy3ClRuMePhPCy3(34 mol %)MeOMeOMe MeOMeMeO0.1 M in C6H6,1.25 h, 25 C(75-81%)OMeMeMeOOMeOMeMeRing-opening/cross metathesis/ring-closing metathesisA. B. Smith and co-workers, J. Am. Chem. Soc. 2001, 123, 5925.Me
Ring-Closing Olefin Metathesis:Applications in the Synthesis of Designed MoleculesO Me Me ON NO MeMe ON NON NO H H OO HNNH O O HNNNNNHMe O O MeCDCl3, 25 C, 48 h(65%)Cross metathesis/RCMO Me Me ON NNHOO HNNONHH ONNMe O O MePhPCy3ClRuPhClPCy3 (20 mol %)O MeMe ON NN NO H H OH O O HNNNNMe O OMe O O MeONHH ONNMeT. D. Clark, M. R. Ghadiri, J. Am. Chem. Soc. 1995, 117, 12364.
Enyne Metathesis:Background and Principles of SelectivityIntramolecular enyne metathesis[Ru][Ru]0-4- [Ru][Ru]0-40-4[Ru]0-4For a review, see: S. T. Diver, A. J. Geissert, Chem. Rev. 2004, 104, 1317.0-4
Enyne Metathesis:Background and Principles of SelectivityIntramolecular enyne metathesis[Ru][Ru]- [Ru][Ru]0-40-40-4[Ru]0-40-4Note the insertion into the terminal alkene; with ring sizes above 8,products looking like intermolecular enyne adducts result!Intermolecular enyne metathesisR2R1[Ru]R2R1[Ru]R1[Ru]R2R2R1[Ru]- [Ru]R2R2R2For a review, see: S. T. Diver, A. J. Geissert, Chem. Rev. 2004, 104, 1317.R1R2
Enyne Metathesis:Selected Examples in Total lRuClMeO2COPhHNOPCy3benzene,50 C, 11 h(87%)EnynemetathesisCDCl3,50 C24 T. R. Hoye and co-workers, Org. Lett. 1999, 1, 277.M. Mori and co-workers, J. Org. Chem. 1996, 61, 8356.HOOHHNstemomideO
Enyne Metathesis:Applications in Total mercontrol elementMeOTBSMeOMeMeOTBSOROOTBSTBSOHHOTBSR TBSTBSOM. D. Shair and co-workers, J. Am. Chem. Soc. 2002, 124, 773.
Enyne Metathesis:Applications in Total SynthesisMeTBSOMeClPCy3ClRuPCy3(50 mol %)OMeH2C CH2,CH2Cl2,40 C, 21 h(42%)Enyne metathesisTBSOMeOROMeMeRemovableatropisomercontrol OTBSR TBSTBSOHMeOMeOTBSMePh(40 mol %)TBSOTBSOMeOH2C CH2,toluene,45 C, 40 h(31%)Enyne metathesisM. D. Shair and co-workers, J. Am. Chem. Soc. 2002, 124, 773.OTBSTBSOHOTBS
Cascades of Metathesis Reactions:Applications in the Synthesis of Designed MoleculesOTBDPSClPCy3ClRuOTBDPSPhPCy3(4 mol %)MeC6H6, 25 C, 4 h-[H2C CH2]Enyne metathesis[Ru]MeR. H. Grubbs and co-workers, J. Org. Chem. 1998, 63, 4291.
Cascades of Metathesis Reactions:Applications in the Synthesis of Designed MoleculesOTBDPSClPCy3ClRuOTBDPSPhPCy3(4 mol %)C6H6, 25 C, 4 h-[H2C CH2]Enyne metathesisMe[Ru]MeOTBDPSOTBDPSEnyne metathesisdomino sequence(70%)Me[Ru]R. H. Grubbs and co-workers, J. Org. Chem. 1998, 63, 4291.
Ring-Closing Alkyne Metathesis:Applications in Total SynthesisMeMeSTBSONOOOTBS OA(10 mol %)STBSOtoluene/CH2Cl280 C, 8 h(80%)Alkyne metathesisNOOOTBS O1. H2, Lindlar cat.(79% overall)2. HFNN MoSHONNOOAOHOepothilone CA. Furstner and co-workers, J. Am. Chem. Soc. 1999, 121, 9453.T. J. Katz, T. M. Sivavec, J. Am. Chem. Soc. 1985, 107, 737.
Alkyne Metathesis:Applications in Total SynthesisOMeOTBSOOMeOA(10 mol %)toluene/CH2Cl2Me80 C, 16 h(73%)Alkyne metathesisOTBSOOMe1. H2, Lindlar cat.(74% overall)2. HFNN MoONOHOAOMeprostaglandin E-1,15-lactoneA. Furstner and co-workers, Angew. Chem. Int. Ed. 2000, 39, 1234.
Ring-Closing Olefin Metathesis:How to Handle Long-Standing ProblemsPCy3ClRuClNOHNHPCy3Ph(20 mol %)CH2Cl2, Δ, 3.5 h(62%)(1.7:1, Z/E)Ring-closingmetathesisNOHNHnakadomarin AD. J. Dixon and co-workers, J. Am. Chem. Soc. 2009, 131, 16632.
Ring-Closing Olefin Metathesis:How to Handle Long-Standing ProblemsClClNN WOArNOHNHAr(5 mol %)toluene, rt, 8 h(63%)(15.6:1, Z/E)Ring-closingmetathesisNOHNHnakadomarin AD. J. Dixon, R.R. Schrock, A. H. Hoveyda and co-workers, Nature 2011, 479, 88.
Ring-Closing Olefin Metathesis:Deploy JudiciouslyOOOOHD. J. Dixon, R.R. Schrock, A. H. Hoveyda and co-workers, Nature 2011, 479, 88.
Ring-Closing Olefin Metathesis:Deploy JudiciouslyOOOOHD. J. Dixon, R.R. Schrock, A. H. Hoveyda and co-workers, Nature 2011, 479, 88.
Ring-Closing Olefin Metathesis:Deploy JudiciouslyOOOOHD. J. Dixon, R.R. Schrock, A. H. Hoveyda and co-workers, Nature 2011, 479, 88.
Ring-Closing Olefin Metathesis:Applications in Total ne, 100 C2. PPTS(23% overall)Ring-closingmetathesisMeOONHONOSOOH OHgriseoviridinA. I. Meyers and co-workers, Angew. Chem. Int. Ed. 2000, 39, 1664.NH
Alkene Metathesis Reactions: What are Effective Initiators for the Process? Acids A lcohols, Water Ald ehydes Ke tones Esters, Amides Olefins Acids lcohs,Water Al ehys Ktons Olefins Esters, Amides Acids Alcohols, Water Aldehydes Olefins Ketones Esters, Amides Functional group reactivity Mo N
Chemical Reactions Slide 3 / 142 Table of Contents: Chemical Reactions · Balancing Equations Click on the topic to go to that section · Types of Chemical Reactions · Oxidation-Reduction Reactions · Chemical Equations · Net Ionic Equations · Types of Oxidation-Reduction Reactions · Acid-Base Reactions · Precipitation Reactions
ii. acid–base neutralization reactions iii. oxidation–reduction or redox reactions. Q.3. What are the important aspects of redox reactions? Ans: Almost every element participate in redox reactions. The important aspects of redox reactions are as follows: i. Large number of natural, biological and industrial processes involve redox reactions .
CHICAGO BUILDING CODE. Title 14B of the Municipal Code of Chicago. CHICAGO CONSTRUCTION CODES. As defined in Chapter 14A-2. CHICAGO ELECTRICAL CODE. Title 14E of the Municipal Code of Chicago. CHICAGO ENERGY CONSERVATION CODE. Title 14N of the Municipal Code of Chicago. CHICAGO FIRE PREVENTION CODE. Title 14F of the Municipal Code of Chicago.
Special Topic 6.1: Oxidizing Agents and Aging 6.2 Oxidation Numbers Internet: Balancing Redox Reactions 6.3 Types of Chemical Reactions Combination Reactions Decomposition Reactions Combustion Reactions Special Topic 6.2: Air Pollution and Catalytic Converters Single-Displacement Reactions Internet: Single-Displacement Reaction 6.4 Voltaic Cells
The Major Classes of Chemical Reactions. 4.6 Elements in Redox Reactions 4.1 The Role of Water as a Solvent 4.2 Writing Equations for Aqueous Ionic Reactions 4.3 Precipitation Reactions 4.4 Acid -Base Reactions. 4.5 Oxidation -Reduction (Redox) Reactions 4.7
Types of Reactions There are five main types of chemical reactions we will talk about: 1. Synthesis reactions 2. Decomposition reactions 3. Single displacement reactions 4. Double displacement reactions 5. Comb
endo substrate gave only the regioisomer of a 1-2 type (E/Z, 1:1), whereas the exo substrate yielded a mixture of products of types 1-2 and 1-3 (9:1; E/Z 0.9:1). Arjona, Blechert and others have suggested that a competing ring-opening metathesis polymerization (ROMP) can be minimized by carrying out the reaction in high dilution.
Accounting The Accounting programme is written by Niall Lothian, formerly Professor at Edinburgh Business School, Heriot-Watt University, and John Small, Professor Emeritus at Heriot-Watt University. Both have previously occupied chairs in the University’s Department of Accountancy and Finance.
