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{{Distinguish|Petasis reaction}}{{chembox| Verifiedfields = changed| Watchedfields = changed| verifiedrevid = 404448904| ImageFile = Petasis reagent V1.svg| ImageSize = 120px| ImageName = Structural formula of the Petasis reagent| ImageFile1 = Petasis-reagent-3D-balls.png| ImageSize1 = 120px | ImageName1 = Ball-and-stick model of the Petasis reagent| IUPACName = Bis(η5-cyclopentadienyl)dimethyltitanium| OtherNames = Dimethyltitanocene|Section1={{Chembox Identifiers| SMILES = [Ti](C)(C).c1[cH-]ccc1.c2[cH-]ccc2

changed|chemspider}}| ChemSpiderID = 34981143| InChI = 1/2C5H5.2CH3.Ti/c2*1-2-4-5-3-1;;;/h2*1-5H;2*1H3;/q2*-1;;;+2/r2C5H5.C2H6Ti/c2*1-2-4-5-3-1;1-3-2/h2*1-5H;1-2H3/q2*-1;+2| InChIKey = AFEQRLILWYRIDQ-MEMJIDHRAL

changed|chemspider}}| StdInChI = 1S/2C5H5.2CH3.Ti/c2*1-2-4-5-3-1;;;/h2*1-5H;2*1H3;/q2*-1;;;+2

changed|chemspider}}| StdInChIKey = AFEQRLILWYRIDQ-UHFFFAOYSA-N| PubChem = 71308256| EINECS = 679-889-8

correct|??}}| CASNo = 1271-66-5| RTECS = }}|Section2={{Chembox Properties| Formula = C12H16Ti| MolarMass = 208.13 g/mol }}|Section7={{Chembox Hazards| ExternalSDS = | MainHazards = Irritant, incompatible with water and oxidizing agents| FlashPt =| GHSPictograms = {{GHS02}}{{GHS07}}{{GHS08}}| GHSSignalWord = Danger

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}} }}|Section8={{Chembox Related| OtherCompounds = }} }}The Petasis reagent, named after Nicos A. Petasis, is an organotitanium compound with the formula Cp2Ti(CH3)2.JOURNAL, N. A. Petasis, E. I. Bzowej, amp, Titanium-mediated carbonyl olefinations. 1. Methylenations of carbonyl compounds with dimethyltitanocene, 1990, J. Am. Chem. Soc., 112, 17, 6392–6394, 10.1021/ja00173a035, It is an orange-colored solid. Preparation and use The Petasis reagent is prepared by the salt metathesis reaction of methylmagnesium chloride or methyllithiumJOURNAL, Claus, K., Bestian, H., Justus Liebigs Ann. Chem., 1962, 654, 8–19, 10.1002/jlac.19626540103, Über die Einwirkung von Wasserstoff auf einige metallorganische Verbindungen und Komplexe, with titanocene dichloride:{{OrgSynth | author = Payack, J. F. | author2 = Hughes, D. L. | author3 = Cai, D. | author4 = Cottrell, I. F. | author5 = Verhoeven, T. R. | prep = v79p0019 | volume = 79 | pages = 19 | year = 2002 | title = Dimethyltitanocene}} Cp2TiCl2 + 2 CH3MgCl → Cp2Ti(CH3)2 + 2 MgCl2 This compound is used for the transformation of carbonyl groups to terminal alkenes. It exhibits similar reactivity to the Tebbe reagent and Wittig reaction. Unlike the Wittig reaction, the Petasis reagent can react with a wide range of aldehydes, ketones and esters.JOURNAL, 10.1016/j.tet.2007.03.015, Titanium carbenoid reagents for converting carbonyl groups into alkenes, Hartley, R. C., Li, J., Main, C. A., McKiernan, G. J., Tetrahedron (journal), Tetrahedron, 2007, 63, 4825–4864, 23, The Petasis reagent is also very air stable, and is commonly used in solution with toluene or THF.The Tebbe reagent and the Petasis reagent share a similar reaction mechanism. The active olefinating reagent, Cp2TiCH2, is generated in situ upon heating. With the organic carbonyl, this titanium carbene forms a four membered oxatitanacyclobutane that releases the terminal alkene.JOURNAL, Meurer, Eduardo Cesar, Santos, Leonardo Silva, Pilli, Ronaldo Aloise, Eberlin, Marcos N., Probing the Mechanism of the Petasis Olefination Reaction by Atmospheric Pressure Chemical Ionization Mass and Tandem Mass Spectrometry, Organic Letters, 5, 1391–4, 2003, 10.1021/ol027439b, 9, 12713281, 300px|Formation of the active olefinating reagent 500px|Reaction of the active olefinating reagent with a carbonyl compound In contrast to the Tebbe reagent, homologs of the Petasis reagent are relatively easy to prepare by using the corresponding alkyllithium instead of methyllithium, allowing the conversion of carbonyl groups to alkylidenes.{{Citation|last1=Petasis|first1=Nicos A.|title=Bis(cyclopentadienyl)dimethyltitanium|date=2012-03-15|encyclopedia=Encyclopedia of Reagents for Organic Synthesis|pages=rb126.pub3|editor-last=John Wiley & Sons, Ltd.|place=Chichester, UK|publisher=John Wiley & Sons, Ltd.|language=en|doi=10.1002/047084289x.rb126.pub3|isbn=978-0-471-93623-7|last2=Morshed|first2=M. Monzur|last3=Ahmad|first3=M. Syarhabil|last4=Hossain|first4=M. Mahmun|last5=Trippier|first5=Paul C.}} See also Nysted reagent Titanium–zinc methylenation References {{Reflist}}{{Titanium compounds}}{{Cyclopentadienide complexes}}