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	{{chembox		{{chembox
			|Verifiedfields = changed
⚫	| Name = Tebbe's reagent
			|Watchedfields = changed
⚫	| ImageFile = TebbeRgt.png
			|verifiedrevid = 401050656
	<!-- | ImageSize = 200px -->
	| ImageName = Structure of Tebbe's reagent		|Name = Tebbe's reagent
		⚫	|ImageFile = TebbeRgt.png
⚫	| ImageFile1 = Tebbe's-reagent-3D-balls.png
	<!-- | ImageSize1 = 200px -->		|ImageSize = 200px
	| ImageName1 = Ball-and-stick model of Tebbe's reagent		|ImageName = Structure of Tebbe's reagent
		⚫	|ImageFile1 = Tebbe's-reagent-3D-balls.png
⚫	| IUPACName = μ-Chlorodimethyl(μ-methylene)titaniumaluminum
			|ImageSize1 = 200px
	| OtherNames = Tebbe reagent
			|ImageName1 = Ball-and-stick model of Tebbe's reagent
⚫	| Section1 = {{Chembox Identifiers
		⚫	|IUPACName = μ-Chlorodimethyl(μ-methylene)titaniumaluminum
⚫	| CASNo = 67719-69-1
		⚫	|OtherNames = Tebbe reagent
⚫	}}
	| Section2 = {{Chembox Properties		|Section1 = {{Chembox Identifiers
			|CASNo_Ref = {{cascite|correct|??}}
⚫	| Formula = C<sub>13</sub>H<sub>18</sub>AlClTi
		⚫	|CASNo = 67719-69-1
⚫	| MolarMass = 284.60 g/mol
			|UNII_Ref = {{fdacite|correct|FDA}}
⚫	| Solvent = other solvents
			|UNII = V040SDB67S
⚫	| SolubleOther = toluene, benzene, dichloromethane,<br />THF (low temperatures only)}}
			|PubChem = 53384502
			|ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}}
			|ChemSpiderID = 34981139
			|SMILES = C1(C1)C.1cccc1.1cccc1
			|InChI = 1/2C5H5.2CH3.CH2.Al.Cl.Ti/c2*1-2-4-5-3-1;;;;;;/h2*1-5H;2*1H3;1H2;;;/q2*-1;;;;-1;+1;+2/r2C5H5.C3H8AlClTi/c2*1-2-4-5-3-1;1-4(2)3-6-5-4/h2*1-5H;3H2,1-2H3/q2*-1;+2
			|InChIKey = FHPQZKBPAZOMGO-SBUAZLESAR
			|StdInChI_Ref = {{stdinchicite|changed|chemspider}}
			|StdInChI = 1S/2C5H5.2CH3.CH2.Al.Cl.Ti/c2*1-2-4-5-3-1;;;;;;/h2*1-5H;2*1H3;1H2;;;/q2*-1;;;;-1;+1;+2
			|StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
			|StdInChIKey = FHPQZKBPAZOMGO-UHFFFAOYSA-N
	}}		}}
		⚫	|Section2 = {{Chembox Properties
⚫	The '''Tebbe reagent''' is the ] with the formula (C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>TiCH<sub>2</sub>ClAl(CH<sub>3</sub>)<sub>2</sub>. It used in the methylenation of ] compounds, that is it converts organic compounds containing the R<sub>2</sub>C=O group into the related R<sub>2</sub>C=CH<sub>2</sub> derivative.<ref>{{cite journal | author = F. N. Tebbe, G. W. Parshall and G. S. Reddy | title = Olefin homologation with titanium methylene compounds | year = 1978 | journal = ] | volume = 100 | issue = 11 | pages = 3611–3613 | doi = 10.1021/ja00479a061}}</ref> It is a red solid that is ] in the air, and thus is typically handled with ]s.
		⚫	|Formula = C<sub>13</sub>H<sub>18</sub>AlClTi
		⚫	|MolarMass = 284.60 g/mol
		⚫	|Solvent = other solvents
		⚫	|SolubleOther = toluene, benzene, dichloromethane,<br />THF (low temperatures only)}}
		⚫	}}
		⚫	'''Tebbe's reagent''' is the ] with the formula (C<sub>5</sub>H<sub>5</sub>)<sub>2</sub>TiCH<sub>2</sub>ClAl(CH<sub>3</sub>)<sub>2</sub>. It is used in the ] of ] compounds, that is it converts organic compounds containing the R<sub>2</sub>C=O group into the related R<sub>2</sub>C=CH<sub>2</sub> derivative.<ref>{{cite journal | author = F. N. Tebbe, G. W. Parshall and G. S. Reddy | title = Olefin homologation with titanium methylene compounds | year = 1978 | journal = ] | volume = 100 | issue = 11 | pages = 3611–3613 | doi = 10.1021/ja00479a061}}</ref> It is a red solid that is ] in the air, and thus is typically handled with ]s. It was originally synthesized by ] at ].
	Tebbe's reagent contains two tetrahedral centers linked by a pair of ]s. Titanium features two ] ({{chem||-}}, or Cp) rings, and aluminium features two methyl ligands. The titanium and aluminium atoms are bridged by both ] and chloride ligands. This compound exhibits a nearly square (Ti-CH<sub>2</sub>-Al-Cl) bridge. The Tebbe reagent was the first reported compound where a methylene group bridges a transition metal (Ti) and a main group metal (Al).<ref name="Herrmann">Herrmann, W.A., "The Methylene Bridge" ''Advances in Organometallic Chemistry'' '''1982''', ''20'', 195-197.</ref>		Tebbe's reagent contains two ] metal centers linked by a pair of ]s. The titanium has two ] ({{chem||-}}, or Cp) rings and aluminium has two methyl groups. The titanium and aluminium atoms are linked together by both a ] (-CH<sub>2</sub>-) and a chloride atom in a nearly ] (Ti–CH<sub>2</sub>–Al–Cl) geometry.<ref>{{cite journal |title= Structural Elucidation of the Illustrious Tebbe Reagent |first1= Rick |last1= Thompson |first2= Eiko |last2= Nakamaru-Ogiso |first3= Chun-Hsing |last3= Chen |first4= Maren |last4= Pink |first5= Daniel J. |last5= Mindiola |journal= Organometallics |year= 2014 |volume= 33 |issue= 1 |pages= 429–432 |doi= 10.1021/om401108b }}</ref> The Tebbe reagent was the first reported compound where a methylene bridge connects a transition metal (Ti) and a main group metal (Al).<ref name="Herrmann">Herrmann, W.A., "The Methylene Bridge" ''Advances in Organometallic Chemistry'' '''1982''', ''20'', 195–197.</ref>
	==Preparation==		==Preparation==
	The Tebbe reagent is synthesized from ] and ] in ] solution.<ref name="Herrmann" /><ref name="Strauss">Straus, D. A., "μ-Chlorobis(cyclopentadienyl)(dimethylaluminium)-μ-methylenetitanium": ''Encyclopedia of Reagents for Organic Synthesis.'' John Wiley, London, 2000.</ref>		The Tebbe reagent is synthesized from ] and ] in ] solution.<ref name="Herrmann" /><ref name="Strauss">Straus, D. A., "μ-Chlorobis(cyclopentadienyl)(dimethylaluminium)-μ-methylenetitanium": ''Encyclopedia of Reagents for Organic Synthesis.'' John Wiley, London, 2000.</ref>
	::Cp<sub>2</sub>TiCl<sub>2</sub> + 2 Al(CH<sub>3</sub>)<sub>3</sub> → CH<sub>4</sub> + Cp<sub>2</sub>TiCH<sub>2</sub>AlCl(CH<sub>3</sub>)<sub>2</sub> + Al(CH<sub>3</sub>)<sub>2</sub>Cl		::Cp<sub>2</sub>TiCl<sub>2</sub> + 2 Al(CH<sub>3</sub>)<sub>3</sub> → CH<sub>4</sub> + Cp<sub>2</sub>TiCH<sub>2</sub>AlCl(CH<sub>3</sub>)<sub>2</sub> + Al(CH<sub>3</sub>)<sub>2</sub>Cl
	After about 3 days, the product is obtained after recrystallization to remove Al(CH<sub>3</sub>)<sub>2</sub>Cl.<ref name="Herrmann"/> Although syntheses using the isolated Tebbe reagent give a cleaner product, successful procedures using the reagent "in situ" have been reported.<ref>{{OrgSynth | author = Pine, S. H.; Kim, G.; Lee, V. | title = Enol ethers by methylenation of esters: 1-Phenoxy-1-phenylethene and 3,4-dihydro-2-methylene-2''H''-1-benzopyran | collvol = 8 | collvolpages = 512 | prep = cv8p0512 | year = 1993}}</ref><ref>{{cite journal | author = L. F. Cannizzo and R. H. Grubbs | title = In situ preparation of (&mu;-chloro)(&mu;-methylene)bis(cyclopentadienyl)(dimethylaluminum)titanium (Tebbe's reagent) | year = 1985 | journal = ] | volume = 50 | issue = 13 | pages = 2386–2387 | doi = 10.1021/jo00213a040 }}</ref> Instead of isolating the Tebbe reagent, the solution is merely cooled in an ice bath or dry ice bath before adding the starting material.		After about 3 days, the product is obtained after recrystallization to remove Al(CH<sub>3</sub>)<sub>2</sub>Cl.<ref name="Herrmann"/> Although syntheses using the isolated Tebbe reagent give a cleaner product, successful procedures using the reagent "in situ" have been reported.<ref>{{cite journal | last1 = Pine|first1=S. H.| last2=Kim|first2=V.| last3=Lee| first3=V. | title = Enol ethers by methylenation of esters: 1-Phenoxy-1-phenylethene and 3,4-dihydro-2-methylene-2''H''-1-benzopyran | journal=Org. Synth.|volume = 69 | page = 72 | doi = 10.15227/orgsyn.069.0072 | year = 1990}}</ref><ref>{{cite journal |author1=L. F. Cannizzo |author2=R. H. Grubbs |name-list-style=amp | title = In situ preparation of (μ-chloro)(μ-methylene)bis(cyclopentadienyl)(dimethylaluminum)titanium (Tebbe's reagent) | year = 1985 | journal = ] | volume = 50 | issue = 13 | pages = 2386–2387 | doi = 10.1021/jo00213a040}}</ref> Instead of isolating the Tebbe reagent, the solution is merely cooled in an ice bath or dry ice bath before adding the starting material.
	An alternative but less convenient synthesis entails the use of ] (Petasis reagent):<ref name="Payack2002">{{OrgSynth | author = Payack, J. F.; Hughes, D. L.; Cai, D.; Cottrell, I. F.; Verhoeven, T. R. | title = Dimethyltitanocene | collvol = 10 | collvolpages = 355 | year = 2004 | prep = v79p0019 }}</ref>		An alternative but less convenient synthesis entails the use of ] (Petasis reagent):<ref name="Payack2002">{{OrgSynth | author = Payack, J. F.; Hughes, D. L.; Cai, D.; Cottrell, I. F.; Verhoeven, T. R. | title = Dimethyltitanocene | collvol = 10 | collvolpages = 355 | year = 2004 | prep = v79p0019}}</ref>
	::Cp<sub>2</sub>Ti(CH<sub>3</sub>)<sub>2</sub> + Al(CH<sub>3</sub>)<sub>2</sub>Cl &rarr; Cp<sub>2</sub>TiCH<sub>2</sub>AlCl(CH<sub>3</sub>)<sub>2</sub> + CH<sub>4</sub>		::Cp<sub>2</sub>Ti(CH<sub>3</sub>)<sub>2</sub> + Al(CH<sub>3</sub>)<sub>2</sub>Cl → Cp<sub>2</sub>TiCH<sub>2</sub>AlCl(CH<sub>3</sub>)<sub>2</sub> + CH<sub>4</sub>
	One drawback to this method, aside from requiring Cp<sub>2</sub>Ti(CH<sub>3</sub>)<sub>2</sub>, is the difficulty of separating product from unreacted starting reagent.		One drawback to this method, aside from requiring Cp<sub>2</sub>Ti(CH<sub>3</sub>)<sub>2</sub>, is the difficulty of separating product from unreacted starting reagent.
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	:]		:]
	Also analogous to the Wittig reagent, the reactivity appears to be driven by the high ]ity of Ti(IV). The Schrock carbene ('''1''') reacts with carbonyl compounds ('''2''') to give a postulated oxatitanacyclobutane intermediate ('''3'''). This cyclic intermediate has never been directly isolated, presumably because it breaks down immediately to the produce the desired ] ('''5''').		Also analogous to the Wittig reagent, the reactivity appears to be driven by the high ] of Ti(IV). The Schrock carbene ('''1''') reacts with carbonyl compounds ('''2''') to give a postulated oxatitanacyclobutane intermediate ('''3'''). This cyclic intermediate has never been directly isolated, presumably because it breaks down immediately to the produce the desired ] ('''5''').
	:]		:]
	==Scope==		==Scope==
	The Tebbe reagent is used in ] for carbonyl methylenation.<ref>''Titanium carbenoid reagents for converting carbonyl groups into alkenes" Hartley, R. C.; Li, J.; Main, C. A.; McKiernan, G. J. Tetrahedron 2007, 63, 4825-4864 (Review).</ref><ref name="Pine1993">Pine, S. H. ''Org. React.'' '''1993''', ''43'', 1. (Review)</ref><ref name=""Beadham2005">Beadham, I.; Micklefield, J. ''Curr. Org. Syn.'' '''2005''', ''2'', 231-250. (Review)</ref> This conversion can also be effected using the ], although the Tebbe reagent is more efficient especially for sterically encumbered carbonyls. Furthermore, the Tebbe reagent is less basic than the Wittig reagent and does not give the β-elimination products.		The Tebbe reagent is used in ] for carbonyl methylidenation.<ref>{{cite journal |doi=10.1016/j.tet.2007.03.015|title=Titanium carbenoid reagents for converting carbonyl groups into alkenes|year=2007|last1=Hartley|first1=Richard C.|last2=Li|first2=Jianfeng|last3=Main|first3=Calver A.|last4=McKiernan|first4=Gordon J.|journal=Tetrahedron|volume=63|issue=23|pages=4825–4864}}</ref>
			<ref name="Pine1993">Pine, S. H. ''Org. React.'' '''1993''', ''43'', 1. (Review)</ref><ref name="Beadham2005">Beadham, I.; Micklefield, J. ''Curr. Org. Synth.'' '''2005''', ''2'', 231–250. (Review)</ref> This conversion can also be effected using the ], although the Tebbe reagent is more efficient especially for sterically encumbered carbonyls. Furthermore, the Tebbe reagent is less basic than the Wittig reagent and does not give the β-elimination products.
	Methylenation reactions also occur for ] as well as ], ] and ]s. The Tebbe reagent converts esters and lactones to enol ethers and amides to enamines. In compounds containing both ketone and ester groups, the ketone selectively reacts in the presence of one equivalent of the Tebbe reagent.		Methylidenation reactions also occur for ] as well as ], ] and ]s. The Tebbe reagent converts esters and lactones to enol ethers and amides to enamines. In compounds containing both ketone and ester groups, the ketone selectively reacts in the presence of one equivalent of the Tebbe reagent.
	:]		:]
	The Tebbe reagent methylenates carbonyls without racemizing a ] α carbon. For this reason, the Tebbe reagent has found applications in reactions of sugars where maintenance of ] can be critical.<ref>{{cite journal | author = A. Marra, J. Esnault, A. Veyrieres and P. Sinay | title = Isopropenyl glycosides and congeners as novel classes of glycosyl donors: theme and variations | year = 1992 | journal = ] | volume = 114 | issue = 16 | pages = 6354–6360 | doi = 10.1021/ja00042a010}}</ref>		The Tebbe reagent methylidenates carbonyls without racemizing a ] α carbon. For this reason, the Tebbe reagent has found applications in reactions of sugars where maintenance of ] can be critical.<ref>{{cite journal | author = A. Marra, J. Esnault, A. Veyrieres and P. Sinay | title = Isopropenyl glycosides and congeners as novel classes of glycosyl donors: theme and variations | year = 1992 | journal = ] | volume = 114 | issue = 16 | pages = 6354–6360 | doi = 10.1021/ja00042a010}}</ref>
	The Tebbe reagent reacts with ]s to form titanium enolates by replacing Cl<sup>-</sup>.		The Tebbe reagent reacts with ]s to form titanium enolates by replacing Cl<sup>−</sup>.
	:]		:]
			===Modifications===
			It is possible to modify Tebbe's reagent through the use of different ligands. This can alter the reactivity of the complex, allowing for a broader range of reactions. For example, ] can be achieved using a chlorinated analogue.<ref>''Unusual Ambiphilic Carbenoid Equivalent in Amide Cyclopropanation'' Kuo-Wei Lin, Shiuan Yan, I-Lin Hsieh, and Tu-Hsin Yan ]; '''2006'''; 8(11) pp 2265 – 2267; </ref>
			:]
	==See also==		==See also==
			===Related organotitanium reagents and reactions===
			*]
	*]		*]
			*Lombardo reagent<ref>{{cite journal|journal=Organic Syntheses|author= Luciano Lombardo|volume=65|page=81|year=1987|doi=10.15227/orgsyn.065.0081|title=Methylenation of Carbonyl Compounds: (+)-3-Methylene-''cis-p''-menthane}}.</ref>
			*]
			===Related methylidenation reactions===
			*]
	*]		*]
	*]
	*]		*]
	*]		*]
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	==References==		==References==
	{{reflist}}		{{reflist}}
			{{Titanium compounds}}
			{{Aluminium compounds}}
	]		]
	]		]
	]		]
	]		]
			]
	]
	]
	]