| 词条 | Schwartz's reagent |
| 释义 |
| verifiedrevid = 401437383 | ImageFileL1 = Cp4Zr2H2Cl2.png | ImageSizeL1 = 154px | ImageFileR1 = | ImageSizeR1 = 150px | IUPACName = chloridobis(η5-cyclopentadienyl)hydridozirconium | OtherNames = Cp2ZrClH, zirconocene chloride hydride |Section1={{Chembox Identifiers | CASNo = 37342-97-5 | PubChem = | ChemSpiderID = 28605366 | SMILES = [cH-]1cccc1.[cH-]1cccc1.Cl[ZrH+2] | InChI = 1/2C5H5.ClH.Zr.H/c2*1-2-4-5-3-1;;;/h2*1-5H;1H;;/q2*-1;;+3;/p-1/r2C5H5.ClHZr/c2*1-2-4-5-3-1;1-2/h2*1-5H;2H/q2*-1;+2 | InChIKey = GBJQOFBMEJYDAU-CFXPZLBWAB | StdInChI = 1S/2C5H5.ClH.Zr.H/c2*1-2-4-5-3-1;;;/h2*1-5H;1H;;/q2*-1;;+3;/p-1 | StdInChIKey = GBJQOFBMEJYDAU-UHFFFAOYSA-M |Section2={{Chembox Properties | Formula = C10H11ClZr | MolarMass = 257.87 g/mol | Appearance = White solid | Density = | MeltingPt = | BoilingPt = | Solubility = |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }}Schwartz's reagent is the common name for the chemical compound with the formula (C5H5)2ZrHCl, sometimes called zirconocene hydrochloride or zirconocene chloride hydride, and is named after Jeffrey Schwartz, a chemistry professor at Princeton University. This metallocene is used in organic synthesis for various transformations of alkenes and alkynes.[1][2][3] PreparationThe complex was first prepared in crude form by Wailes and Weigold.[4] It can be purchased or readily prepared by reduction of zirconocene dichloride with lithium aluminium hydride: (C5H5)2ZrCl2 + {{1/4}} LiAlH4 → (C5H5)2ZrHCl + {{1/4}} LiAlCl4 In practice this reaction also affords (C5H5)2ZrH2, which is treated with methylene chloride to give the mixed hydride chloride.[5] An alternative procedure that generated Schwartz's Reagent from dihydride has also been reported.[6] StructureSchwartz's exact structure has not been determined by X-ray crystallography, but other methods have determined certain details. FT-IR spectroscopy established that the hydrides are bridging. Solid state NMR spectroscopy also indicates a dimeric structure, which is consistent with the X-ray crystallographic structure for the analogous (C5H5)4Zr2H2(CH3)2 compound.[7] Uses in organic synthesisSchwartz's reagent can be used for a number of reactions. It has been shown that it can be used to reduce amides to aldehydes. Reducing tertiary amides with Schwartz's reagent can reach efficient yields, but primary and secondary amides will show decreased yields. The use of Schwartz's reagent in this manner will not require any added heat and can be done quickly, and reduction of the alcohol form is not a problematic side reaction as it can be with other reducing agents. Schwartz's reagent will selectively reduce the amide over any readily reducible esters that may be present in the reaction mixture.[8] Vinylation of ketones in high yields is a possible use of Schwartz's reagent.[9] Schwartz's reagent is used in the synthesis of some macrolide antibiotics,[10][11] (−)-motuporin,[12] and antitumor agents.[13] HydrozirconationHydrozirconation is a form of hydrometalation. Substrates for hydrozirconation are alkenes and alkynes. With terminal alkynes the terminal vinyl zirconium product is predominantly formed. Secondary reactions are nucleophilic additions, transmetalations,[14] conjugate additions,[15] coupling reactions, carbonylation and halogenation. Computational studies indicate that hydrozirconation occurs from the interior portion.[16][17]When treated with one equivalent of Cp2ZrClH, diphenylacetylene gives the corresponding alkenylzirconium as a mixture of cis and trans isomers. With two equivalents of hydride, the endproduct was a mixture of erythro and threo zircono alkanes: In 1974 Hart and Schwartz reported that the organozirconium intermediates react with electrophiles such as hydrochloric acid, bromine and acid chlorides to give the corresponding alkane, bromoalkanes, and ketones:[18] The corresponding organoboron and organoaluminum compounds were already known, but these are air-sensitive and/or pyrophoric whereas organozirconium compounds are not. ScopeIn one study the usual regioselectivity of an alkyne hydrozirconation is reversed with the addition of zinc chloride:[19][20] One example of a one-pot hydrozirconation - carbonylation - coupling is depicted below:[21][22] With certain allyl alcohols, the alcohol group is replaced by nucleophilic carbon forming a cyclopropane ring:[23]The selectivity of the hydrozirconation of alkynes has been studied in detail.[24][25] Generally, the addition of the Zr–H proceeds via the syn-addition. The rate of addition to unsaturated carbon-carbon bonds is terminal alkyne > terminal alkene ≈ internal alkyne > disubstituted alkene [26] Acyl complexes can be generated by insertion of CO into the C–Zr bond resulting from hydrozirconation.[27] Upon alkene insertion into the zirconium hydride bond, the resulting zirconium alkyl undergoes facile rearrangement to the terminal alkyl and therefore only terminal acyl compounds can be synthesized in this way. The rearrangement most likely proceeds via β-hydride elimination followed by reinsertion. References1. ^{{cite journal | first1=D. W. |last1=Hart |first2=J. |last2=Schwartz| title=Hydrozirconation. Organic Synthesis via Organozirconium Intermediates. Synthesis and Rearrangement of Alkylzirconium(IV) Complexes and Their Reaction with Electrophiles| journal=J. Am. Chem. Soc.| volume=96 | issue=26| year=1974 | pages=8115–8116 | doi = 10.1021/ja00833a048}} 2. ^{{cite journal | first1=J. |last1=Schwartz |first2=J. A. |last2=Labinger| title=Hydrozirconation: A New Transition Metal Reagent for Organic Synthesis | journal=Angew. Chem. Int. Ed.| volume= 15 | issue=6| year=2003| pages=330–340| doi =10.1002/anie.197603331}} 3. ^{{cite journal | first1=Donald W. |last1=Hart |first2=Thomas F. |last2=Blackburn |first3=Jeffrey |last3=Schwartz| title=Hydrozirconation. III. Stereospecific and regioselective functionalization of alkylacetylenes via vinylzirconium(IV) intermediates| journal=J. Am. Chem. Soc.| volume= 97 | issue=3| year=1975| pages=679–680 | doi = 10.1021/ja00836a056}} 4. ^{{cite journal | first1= P. C.|last1= Wailes |first2= H.|last2= Weigold | title = Hydrido complexes of zirconium I. Preparation | journal = J. Organomet. Chem. | year = 1970 | volume = 24 | pages = 405–411 | doi = 10.1016/S0022-328X(00)80281-8 | issue = 2}} 5. ^{{OrgSynth | first1=S. L.|last1= Buchwald |first2=S. J.|last2= LaMaire |first3=R. B. |last3=Nielsen |first4=B. T.|last4= Watson|first5= S. M.|last5= King| title=Schwartz's Reagent| collvol = 9| collvolpages=162 | prep = CV9P0162}} 6. ^{{cite journal | first1=Peter|last1= Wipf |first2=Hidenori|last2= Takahashi |first3=Nian |last3=Zhuang| title=Kinetic vs. thermodynamic control in hydrozirconation reactions| journal=Pure Appl. Chem.| volume= 70 | issue=5| year=1998| pages=1077–1082| url = http://www.iupac.org/publications/pac/1998/pdf/7005x1077.pdf| doi=10.1351/pac199870051077}} 7. ^{{cite journal|author=Rossini, A. J.|author2=Mills, R. W.|author3=Briscoe, G. A.|author4=Norton, E. L.|author5=Geier, S. J.|author6=Hung, I.|author7=Zheng, S.|author8=Autschbach, J.|author9=Schurko, R. W.|title=Solid-State Chlorine NMR of Group IV Transition Metal Organometallic Complexes|journal=Journal of the American Chemical Society|year=2009|volume=131|pages=3317–3330|doi=10.1021/ja808390a}} 8. ^{{cite journal | first1= M. W. |last1=Leighty|first2= J. T.|last2= Spletstoser |first3=Gunda I. |last3=Georg | title=Mild Conversion of Tertiary Amides to Aldehydes Using Cp2ZrHCl (Schwartz’s Reagent)| journal=Org. Synth.| volume= 88| year=2011| pages=427–437}} 9. ^{{cite journal | first1= H. |last1=Li|first2= P. J. |last2=Walsh | title=Catalytic Asymmetric Vinylation and Dienylation of Ketones| journal=J. Am. Chem. Soc.| volume= 127| year=2005| pages=8355–8361| doi= 10.1021/ja0425740}} 10. ^{{cite journal | first1= Matthew O.|last1= Duffey|first2= Arnaud |last2=Le Tiran |first3= James P. |last3=Morken | title=Enantioselective Total Synthesis of Borrelidin| journal=J. Am. Chem. Soc.| volume= 125| year=2003| pages=1458–1459| doi = 10.1021/ja028941u}} 11. ^{{cite journal | first1= J. |last1=Wu|first2= J. S. |last2=Panek | title=Total Synthesis of (−)-Virginiamycin M2: Application of Crotylsilanes Accessed by Enantioselective Rh(II) or Cu(I) Promoted Carbenoid Si–H Insertion| journal=J. Org. Chem.| volume= 76| issue=24 | year=2011| pages=9900–9918 | doi =10.1021/jo202119p}} 12. ^{{cite journal | first1= T.|last1= Hu|first2= J. S.|last2= Panek | title= Total Synthesis of (−)-Motuporin| journal=J. Org. Chem.| volume= 64| year=1999| pages=3000–3001 | doi = 10.1021/jo9904617}} 13. ^{{cite journal | first= K. C. |last=Nicolaou| title=Total Synthesis of Apoptolidin: Completion of the Synthesis and Analogue Synthesis and Evaluation| journal=J. Am. Chem. Soc.| volume= 125| year=2003| pages=15443–15454 | doi = 10.1021/ja030496v|display-authors=etal}} 14. ^{{cite journal |title =Allylic alcohols by alkene transfer from zirconium to zinc: 1-[(tert-butyldiphenylsilyl)oxy]-dec-3-en-5-ol|journal=Organic Syntheses|date=1998|volume=9|issue=74|pages=205|url = http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=cv9p0143 | accessdate = 2013-03-23| quote = Organic Syntheses, Coll. Vol. 9, p.143 (1998); Vol. 74, p.205 (1997).}} 15. ^Conjugate Addition Of A Vinylzirconium Reagent: 3-(1-Octen-1-Yl)Cyclopentanone, Organic Syntheses, Coll. Vol. 9, p.640 (1998); Vol. 71, p.83 (1993). 16. ^{{cite journal | first1= E. Y.|last1= Pankratyev|first2= T. V.|last2= Tyumkina|first3= L. V.|last3= Parfenova|first4= S. L.|last4= Khursan|first5= L. M. |last5=Khalilov|first6= U. M. |last6=Dzhemilev | title=DFT and Ab Initio Study on Mechanism of Olefin Hydroalumination by XAlBui2 in the Presence of Cp2ZrCl2 Catalyst. II.(1) Olefin Interaction with Catalytically Active Centers| journal=Organometallics| volume= 30 | issue=22| year=2011| pages=6078–6089| doi = 10.1021/om200518h}} 17. ^{{cite journal | first1=Juping |last1=Wang |first2=Huiying |last2=Xu |first3=Hui |last3=Gao |first4=Cheng-Yong |last4=Su |first5=Cunyuan |last5=Zhao |first6=David Lee |last6=Phillips| title=DFT Study on the Mechanism of Amides to Aldehydes Using Cp2Zr(H)Cl| journal=Organometallics| volume=29 | issue=1| year=2010| pages=42–51 | doi = 10.1021/om900371u}} 18. ^{{Cite journal | last1 = Hart | first1 = D. W. | last2 = Schwartz | first2 = J. | title = Hydrozirconation. Organic Synthesis via Organozirconium Intermediates. Synthesis and Rearrangement of Alkylzirconium(1V) Complexes and Their Reaction with Electrophiles | doi = 10.1021/ja00833a048 | journal = Journal of the American Chemical Society | volume = 96 | issue = 26 | pages = 8115–8116 | year = 1974 | pmid = | pmc = }} 19. ^Directed Hydrozirconation of Propargylic Alcohols Donghui Zhang and Joseph M. Ready J. Am. Chem. Soc., 129 (40), 12088 -12089, 2007. {{DOI|10.1021/ja075215o}} 20. ^The electrophile in this reaction is iodine. The additive is believed to promote kinetic reaction control. 21. ^Palladium-catalyzed coupling reaction of acylzirconocene chlorides with hypervalent iodonium salts: synthesis of aryl-substituted ketones Suk-Ku Kang and Seok-Keun Yoon J. Chem. Soc., Perkin Trans. 1, 2002, 459 - 461, {{DOI|10.1039/b110983a}} 22. ^Reagents: phenylacetylene, Schwartz's reagent, tetraphenylpalladium and the iodane diphenyliodoniumtetrafluoroborate (phenyl group donor) 23. ^A one-pot access to cyclopropanes from allylic ethers via hydrozirconation–deoxygenative ring formation Vincent Gandon, Jan Szymoniak, Chem. Commun., 2002, (12),1308-1309 {{DOI| 10.1039/b203762a}} 24. ^{{OrgSynth | first1=R. C. |last1=Sun |first2=M. |last2=Okabe |first3=D. L. |last3=Coffen|first4=J. |last4=Schwartz | title=Conjugate Addition of a Vinylzirconium Reagent: 3-(1-Octene-1-yl)cyclopentanone | collvol = 9| year=1998 | collvolpages=640 | prep = cv9p0640}} 25. ^{{cite journal | last1=Panek |first1=J. S.|last2= Hu |first2=T.| title= Stereo- and Regiocontrolled Synthesis of Branched Trisubstituted Conjugated Dienes by Palladium(0)-Catalyzed Cross-Coupling Reaction| journal=J. Org. Chem.| volume= 62| issue=15| year=1997| pages=4912–4913|doi=10.1021/jo970647a}} 26. ^{{cite journal | first1=Peter |last1=Wipf |first2=Heike|last2= Jahn| title=Synthetic applications of organochlorozirconocene complexes| journal=Tetrahedron| volume= 52 | issue=40| year=1996| pages=12853–12910| doi=10.1016/0040-4020(96)00754-5}} 27. ^{{cite journal | first1=Christopher A.|last1= Bertelo|first2= Jeffrey |last2=Schwartz| title=Hydrozirconation. II. Oxidative homologation of olefins via carbon monoxide insertion into the carbon-zirconium bond| journal=J. Am. Chem. Soc.| volume=97 | issue=1| year=1975| pages=228–230 | doi = 10.1021/ja00834a061}} External links{{commons category}}
6 : Metallocenes|Organozirconium compounds|Cyclopentadienyl complexes|Reagents for organic chemistry|Chloro complexes|Metal hydrides |
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