76089-59-3Relevant academic research and scientific papers
5-Methyoxy-2,3,4,5-tetramethylcyclopent-2-enone, a Synthetic Equivalent For 2,3,4,5-Tetramethylcyclopentadienone: Application to the Synthesis of 1,2,3,4-Tetramethylfulvene.
Pando, Jerome C.,Mintz, Eric A.
, p. 4811 - 4812 (1989)
5-Methoxy-2,3,4,5-tetramethylcyclopent-2-enone was synthesized and found to be a useful synthetic equivalent for 2,3,4,5-Tetramethylcyclopentadienone in the preparation of 1,2,3,4-Tetramethylfulvene.
Gallium Methylene
Bonath, Martin,Maichle-M?ssmer, C?cilia,Sirsch, Peter,Anwander, Reiner
supporting information, p. 8206 - 8210 (2019/05/21)
Despite the eminent importance of metal alkylidene species for organic synthesis and industrial catalytic processes, molecular homoleptic metal methylene compounds [M(CH2)n] as the simplest representatives, have remained elusive. Reports on this topic date back to 1955 when polymeric [Li2(CH2)]n and [Mg(CH2)]n were accessed by pyrolysis of methyllithium and dimethylmagnesium, respectively. However, the insoluble salt-like composition of these compounds has impeded their application as valuable reagents. We report that rare-earth metallocene methyl complexes [(C5Me5)2Ln{(μ-Me)2GaMe2}] (Ln=Lu, Y) trigger the formation of homoleptic gallium methylene [Ga8(μ-CH2)12] from trimethylgallium [GaMe3] (Me=methyl) via a cascade C?H bond activation involving the dodecametallic clusters [(C5Me5)6Ln3(μ3-CH2)6Ga9(μ-CH2)9] as crucial intermediates. Such gallium methylene compounds feature a reversible [Ga8(μ-CH2)12]/[Ga6(μ-CH2)9] oligomer switch in donor solvents and act as Schrock-type methylene-transfer reagents.
Chemoselective dehydrogenative esterification of aldehydes and alcohols with a dimeric rhodium(II) catalyst
Cheng, Junjie,Zhu, Meijuan,Wang, Chao,Li, Junjun,Jiang, Xue,Wei, Yawen,Tang, Weijun,Xue, Dong,Xiao, Jianliang
, p. 4428 - 4434 (2016/07/07)
Dehydrogenative cross-coupling of aldehydes with alcohols as well as dehydrogentive cross-coupling of primary alcohols to produce esters have been developed using a Rh-terpyridine catalyst. The catalyst demonstrates broad substrate scope and good functional group tolerance, affording esters highly selectively. The high chemoselectivity of the catalyst stems from its preference for dehydrogenation of benzylic alcohols over aliphatic ones. Preliminary mechanistic studies suggest that the active catalyst is a dimeric Rh(ii) species, operating via a mechanism involving metal-base-metal cooperativity.
Reactivity Study of Pyridyl-Substituted 1-Metalla-2,5-diaza-cyclopenta-2,4-dienes of Group 4 Metallocenes
Becker, Lisanne,Rei?, Fabian,Altenburger, Kai,Spannenberg, Anke,Arndt, Perdita,Jiao, Haijun,Rosenthal, Uwe
, p. 10826 - 10838 (2016/07/27)
In this work the reactivity of 1-metalla-2,5-diaza-cyclopenta-2,4-dienes of group 4 metallocenes, especially of the pyridyl-substituted examples, towards small molecules is investigated. The addition of H2, CO2, Ph?C≡N, 2-py?C≡N, 1,3-dicyanobenzene or 2,6-dicyanopyridine results in exchange reactions, which are accompanied by the elimination of a nitrile. For CO2, a coordination to the five-membered cycle occurs in case of Cp*2Zr(N=C(2-py)?C(2-py)=N). A 1,4-diaza-buta-1,3-diene complex is formed by H-transfer in the conversion of the analogous titanocene compound with CH3?C≡N, PhCH2?C≡N or acetone. For CH3?C≡N a coupling product of three acetonitrile molecules is established additionally. In order to split off the metallocene from the coupled nitriles, we examined reactions with HCl, PhPCl2, PhPSCl2and SOCl2. In the last case, the respective thiadiazole oxides and the metallocene dichlorides were obtained. A subsequent reaction produced thiadiazoles.
Oxygen atom insertion into iron(II) phenyl and methyl bonds: A key step for catalytic hydrocarbon functionalization
Mei, Jiajun,Pardue, Daniel B.,Kalman, Steven E.,Gunnoe, T. Brent,Cundari, Thomas R.,Sabat, Michal
, p. 5597 - 5605 (2015/02/19)
Oxy-functionalization of metal-alkyl and ?aryl bonds is a key step in potential hydrocarbon oxidation catalysis. However, well-defined examples of M-R to ROH conversion are rare, especially for first-row transition metals. CpFe(CO)(NCMe)Ph reacts with oxygen or hydrogen peroxide to produce benzoic acid. Removing CO from the CpFe(L)(L')Ph framework allows simple oxygen atom insertion into the Fe-Ph bond. CpFe(P(OCH2)3CEt)2Ph reacts with Me3NO in THF to produce PhOH in high yield when Bronsted acids are added. Studies show that light promotes P(OCH2)3CEt dissociation from CpFe(P(OCH2)3CEt)2Ph, which facilitates the conversion to PhOH. The methyl analogue CpFe[P(OCH2)3CEt]2Me reacts with oxidants to produce MeOH.
Synthesis and characterization of cyclopentadienylgallium amide compounds as potential single source precursors to GaN
Perrotin,Kennon, Bretni S.,Twamley, Brendan,Miller, Joel S.,Shapiro, Pamela J.
, p. 216 - 222 (2015/02/19)
The synthesis, spectroscopic characterization, and single crystal X-ray structures of [(η5-C5Me4H)2Ga(μ2-NH2)] (1), [(η5-C5Me5)2Ga(μ2-
Transformation of a phosphorus-bound Cp* moiety in the coordination sphere of manganese carbonyl complexes
Pushkarevsky, Nikolay A.,Konchenko, Sergey N.,Virovets, Alexander V.,Scheer, Manfred
, p. 770 - 779 (2013/03/14)
The reaction of Cp PCl2 with K[Mn(CO)5] yields two novel anionic products, [Mn2(CO)8(μ-PC 11H14O)]- (1-) and [Mn 2(CO)8(μ-PHCp)]- (2-), instead of the expected phosphinidene complexes with a delocalized Mn-P-Mn bond system. By treating these anionic complexes with [Ph3PAuCl], they are converted into corresponding neutral derivatives [Mn2(CO)8(μ- PC11H14O)(μ-AuPPh3)] (3) and [Mn 2(CO)8(μ-PHCp)(μ-AuPPh3)] (4). NMR investigations and X-ray structural analyses for 1-, 3, and 4 show that the compounds 1- and 3 as well as 2- and 4 reveal similar molecular structures in which the neutral complexes 3 and 4 contain AuPPh3 units bridging Mn-Mn bonds. In comparison to 1 and 3, complexes 2 and 4 possess one additional H atom bound at the P atom. The structures of 1 and 3 include a novel bicyclic unit consisting of a C 5 ring of the former Cp* moiety conjugated to a CCC(O)P four-membered ring. The latter is built by a CO group of a former Mn carbonyl fragment connecting a P and a C atom of the cycle. One of the methyl groups of the Cp* ligand became a CH2 unit, resulting in two isomers containing an exocyclic CH2 moiety in the positions three or five of the C5 ring. Both isomers were found in the reaction mixture, with one as the major isomer. The proposed reaction pathway is based on XRD, NMR, and MS data and includes the reduction of a transient [CpP(Mn(CO)5) 2] complex by [Mn(CO)5]-, a proton transfer from the neutral to the reduced complex, and a successive reduction of the protonated species. The neutral bicyclic compound 3, containing a 2-phosphacyclobutanone ring, is light sensitive and decomposes to tetramethylfulvene, possibly by a radical decarbonylation mechanism via a transient phosphacyclobutane derivative, [C5(CH3) 4(CH2)P(Mn(CO)4)2AuPPh3] (5), detected by NMR spectroscopy.
Different inertness of titanocene [Cp2Ti] and decamethyltitanocene [Cp*2Ti] in reactions with N,N-bis(trimethylsilyl)sulfurdiimide - Elimination of tetramethylfulvene and formation of half-titanocene complexes
Kaleta, Katharina,Kessler, Monty,Beweries, Torsten,Arndt, Perdita,Spannenberg, Anke,Rosenthal, Uwe
, p. 3388 - 3393 (2012/09/08)
The reaction of the titanocene alkyne complex [Cp* 2Ti(η2-Me3SiC2SiMe3)] (1) (Cp* = η5-pentamethylcyclopentadienyl) with N,N-bis(trimethylsilyl)sulfurdiimide (2) results in the formation of 1,2,3,4-tetramethylfulvene (3) as well as three titanium complexes 4, 5 and 6. During the reaction, formal elimination of one Cp* ligand induces a series of C-H and N-S bond activation steps, thus yielding the products. The molecular structures of complex 5 and of the free fulvene were determined by X-ray crystallographic analysis. Evidently, in these reactions [Cp* 2Ti] is less stable than [Cp2Ti]; a possible reason was found to be the well-known intramolecular C-H activation yielding the tautomeric tetramethylfulvene hydride species, from which 1,2,3,4-tetramethylfulvene (3) can dissociate. Reaction of decamethyltitanocene complex [Cp* 2Ti(η2-Me3SiC2SiMe3)] with N,N-bis(trimethylsilyl)sulfurdiimide results in the formation of three titanium complexes as well as 1,2,3,4-tetramethylfulvene (3) as the organic byproduct. The molecular structures of metallacyclic half-sandwich titanium complex 5 and - most remarkably - of free 3 (co-crystallised with Me 3SiC2SiMe3) were determined by X-ray crystallographic analysis. Copyright
Reactions of hydrogen sulfide with singly and doubly tucked-in titanocenes
Pinkas, Jiri,Cisarova, Ivana,Horacek, Michal,Kubista, Jiri,MacH, Karel
experimental part, p. 1034 - 1045 (2011/04/25)
Hydrogen sulfide reacts with tucked-in titanocene complexes [Ti(III){η5:η1-C5Me4(CH 2)}Cp*] (Cp* = η5-C5Me 5) (2) and [Ti{η4:η3-C 5Me3(CH2)2}Cp*] (3) and their precursors [Cp*2TiMe] (2a) and [Cp*2Ti(η2-Me3SiC≡CSiMe3)] (3a), respectively, to give the corresponding titanocene hydrosulfides [Cp*2Ti(SH)] (4) and [Cp*2Ti(SH)2] (1), respectively. Hydrogen sulfide also cleaves intramolecular σ- or π-Ti-C bonds in ansa-[TiIII(η1:η5: η5-C5Me4SiMe2CHCH 2SiMe2C5Me4)] (5) and ansa-[Ti II(η2:η5:η5-C 5Me4SiMe2CH=CHSiMe2C 5Me4)] (6), affording hydrosulfides ansa- [(η5-CH2Me2SiC5Me 4)2Ti(SH)] (7) and ansa-[(η5-CH 2Me2SiC5Me4)2Ti(SH) 2] (8). The S-H bonds of hydrosulfides 4 and 7 were able to react with the Ti-C bonds in 2 and 5, affording titanocene sulfides [(Cp*2TiIII)2S] (11) and ansa-[{(η5-CH2Me2SiC5Me 4)2TiIII}2S] (12), respectively. Combination of 7 with 2a gave rise to the mixed titanocene sulfide [ansa-{(η5-CH2SiMe2C5Me 4)2Ti}S(TiCp*2)] (13). The titanium(III) d1 electrons in 11-13 form an electronic triplet state well observable by EPR spectra in toluene glass. All the hydrosulfides were decomposed by sunlight. Compound 1 eliminated Cp*H and H2S, while 4 mainly Cp*H. Apparently formed transient [Cp*TiS] species probably gave rise to the serendipitously isolated cluster [{Cp*Ti(S)} 4] (14). Crystal structures of the all complexes were determined by X-ray diffraction analysis.
On the regioselectivity of alkylation of the (trimethylsilyl) tetramethylcyclopentadienide anion. A new approach to the synthesis of 1,2,3,4-tetramethylfulvene
Krut'ko,Borzov,Veksler
, p. 2182 - 2186 (2007/10/03)
The regioselectivity of alkylation of lithium (trimethylsilyl) tetramethylcyclopentadienide C5Me4SiMe3 -Li+ was studied by 1H and 13C NMR spectroscopy using its reactions with MeI, MeOTs, ClCH2CH 2Br, and ClCH2CH2I in different solvents as representative examples. Sterically non-hindered MeI and MeOTs presumably attack the C atom bonded to the silyl group giving 1,2,3,4,5- pentamethylcyclopentadienylsilane. For bulkier alkyl halides, such as ClCH 2CH2Br and ClCH2CH2I, the regioselectivity of alkylation changes to form preferentially gem-dialkyl-substituted cyclopentadienes. The reaction of C5Me 4SiMe3 -Li+ with formaldehyde affords 1,2,3,4-tetramethylfulvene in a high yield, providing an alternative synthetic approach to a number of ω-functionalized peralkylated cyclopentadienes. The quantum-chemical calculations of the C5Me 4SiMe3 - anion by the RHF and DFT (RMPW1PW91) methods in the valence-split 6-311+G(d,p) basis set are in good agreement with the experimental data.
