4425-82-5Relevant articles and documents
Photo-induced β-elimination of 9-fluorenylmethanol leading to dibenzofulvene
Nageh, Hassan,Zhao, Liming,Nakayama, Akira,Hasegawa, Jun-Ya,Wang, Yue,Nakano, Tamaki
, p. 8431 - 8434 (2017)
An effective photo-induced β-elimination of an alcohol leading to a vinyl compound is introduced for the first time. 9-Fluorenylmethanol was irradiated in a solution using a Xe lamp and was efficiently converted to dibenzofulvene (DBF) (9-methylenefluorene) in the absence of base which is necessary in the corresponding ground-state reaction.
Rare-earth metal methylidene complexes with Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 core structure
Sch?dle, Dorothea,Meermann-Zimmermann, Melanie,Maichle-M?ssmer, C?cilia,Sch?dle, Christoph,T?rnroos, Karl W.,Anwander, Reiner
, p. 18101 - 18110 (2015)
Trinuclear rare-earth metal methylidene complexes with a Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3 structural motif were synthesized by applying three protocols. Polymeric [LuMe3]n (1-Lu) reacts with the sterically demanding amine H[NSiMe3(Ar)] (Ar = C6H3iPr2-2,6) in tetrahydrofuran via methane elimination to afford isolable monomeric [NSiMe3(Ar)]LuMe2(thf)2 (4-Lu). The formation of trinuclear rare-earth metal tetramethyl methylidene complexes [NSiMe3(Ar)]3Ln3(μ3-CH2)(μ3-Me)(μ2-Me)3(thf)3 (7-Ln; Ln = Y, Ho, Lu) via reaction of [LnMe3]n (1-Ln; Ln = Y, Ho, Lu) with H[NSiMe3(Ar)] is proposed to occur via an "intermediate" species of the type [NSiMe3(Ar)]LnMe2(thf)x and subsequent C-H bond activation. Applying Lappert's concept of Lewis base-induced methylaluminate cleavage, compounds [NSiMe3(Ar)]Ln(AlMe4)2 (5-Ln; Ln = Y, La, Nd, Ho) were converted into methylidene complexes 7-Ln (Ln = Y, Nd, Ho) in the presence of tetrahydrofuran. Similarly, tetramethylgallate complex [NSiMe3(Ar)]Y(GaMe4)2 (6-Y) could be employed as a synthesis precursor for 7-Y. The molecular composition of complexes 4-Ln, 5-Ln, 6-Y and 7-Ln was confirmed by elemental analyses, FTIR spectroscopy, 1H and 13C NMR spectroscopy (except for holmium derivatives) and single-crystal X-ray diffraction. The Tebbe-like reactivity of methylidene complex 7-Nd with 9-fluorenone was assessed affording oxo complex [NSiMe3(Ar)]3Nd3(μ3-O)(μ2-Me)4(thf)3 (8-Nd). The synthesis of 5-Ln yielded [NSiMe3(Ar)]2Ln(AlMe4) (9-Ln; Ln = La, Nd) as minor side-products, which could be obtained in moderate yields when homoleptic Ln(AlMe4)3 were treated with two equivalents of K[NSiMe3(Ar)].
Dibenzofulvene, a 1,1-diphenylethylene analogue, gives a π-stacked polymer by anionic, free-radical, and cationic catalysts [2]
Nakano,Takewaki,Yade,Okamoto
, p. 9182 - 9183 (2001)
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Solid phase synthesis of α-amino squaric acid-containing peptides
Maeda, Kentaro,Kiniwa, Yu-Ichi,Ohfune, Yasufumi,Ishiguro, Shinichi,Suzuki, Koichi,Murata, Kazuya,Matsuda, Hideaki,Shinada, Tetsuro
, p. 50639 - 50643 (2014)
A new method has been developed for the synthesis of 3-(1-aminoalkyl)-4-hydroxycyclobut-3-ene-1,2-dione [α-amino squaric acid (α-Asq)]-containing peptides using solid phase peptide synthesis according to an Fmoc protecting group strategy. FmocHN-Gly-[α-Asq]-Oi-Pr was successfully used as a coupling unit in this method, which allowed for the construction of α-Asq-containing hexapeptide libraries including Sq-Gly and Sq-Phe units using the Wang-resin. Peptides containing the α-Asq moiety exhibited inhibitory activity towards a digestive enzyme.
Specific C-C coupling of the labile diruthenium bridging methylene complex, Cp2Ru2(μ-CH2)(CO)2(MeCN), with diazoalkanes (R2C=N2) leading to alkenyl complexes, Cp2Ru2(μ-CH=CR2)(μ-H)(CO)2, and alkenes, CH2=CR2
Akita, Munetaka,Hua, Ruimao,Knox, Selby A.R.,Moro-Oka, Yoshihiko,Nakanishi, Sadahiro,Yates, Michael I.
, p. 71 - 83 (1998)
Treatment of the labile μ-methylene species, Cp2Ru2(μ-CH2)(CO)2(MeCN) 1, with diazoalkanes results in C-C coupling of the alkylidene units. The reaction of monosubstituted diazoalkanes (N2=CHR) and 4-t-butyldiazocyclohexane gives the μ-alkenyl-μ-hydride complexes, Cp2Ru2(μ-CH=CR2)(μ-H)(CO)2 2, as sole products, whereas the reaction of disubstituted aryldiazoalkanes (N2=CR1R2) produces olefins (CH2=CR1R2) together with mixtures of unidentified organometallic compounds. Labeling experiments using 1-d2 (μ-CD2) and 1-13C (μ-13CH2) reveal that the methylene bridge in 1 is converted to the α-CH and μ-H parts in 2 and the alkylidene part of diazoalkane is incorporated into the β-CR2 part of the alkenyl bridge. The olefinic products should come from a η2-olefin intermediate, Cp2Ru2(η2CH2=CHR)(CO) 2 7, resulting from coupling of the two alkylidene fragments within the coordination sphere of the diruthenium core. It is notable that C-H oxidative addition in 7 takes place prior to free rotation of the η2-olefin ligand as judged by the regiospecificity of the labeling experiments. Thus specific coupling of alkylidene units proceeds under mild conditions and this C-C coupling reaction serves as a model system for the carbon chain propagation step of surface-catalyzed reactions such as catalytic CO hydrogenation.
Interrupted Intramolecular Hydroaminomethylation of N-Protected-2-vinyl Anilines: Novel Access to 3-Substitued Indoles or Indoline-2-ols
Daran, Jean-Claude,García-Ríos, Perla H.,Gouygou, Maryse,Hochberger-Roa, Frank,López-Cortés, José G.,Ortega-Alfaro, M. Carmen,Urrutigo?ty, Martine
, (2022/02/11)
A new synthetic alternative to the synthesis of 3-methyl indoles and 3-methyl indoline-2-ols with an excellent atomic economy is presented in this study. It is demonstrated that the intramolecular interrupted hydroaminomethylation (HAM) reaction is a powerful tool for the formation of these compounds, which exhibit wide-ranging biological activity. Several N-Protected-2-vinyl anilines were synthesized and involved in the reaction producing the corresponding 3-methylindole or 3-methyl indoline-2-ol depending on the nature of the N-protecting groups.
Beyond Takai's Olefination Reagent: Persistent Dehalogenation Emerges in a Chromium(III)-μ3-Methylidyne Complex
Anwander, Reiner,Langmann, Jan,Maichle-M?ssmer, C?cilia,Scherer, Wolfgang,Trzmiel, Simon,Werner, Daniel
supporting information, p. 20049 - 20054 (2021/08/06)
Reaction of CHI3 with six equivalents of CrCl2 in THF at low temperatures affords [Cr3Cl3(μ2-Cl)3(μ3-CH)(thf)6] as the first isolable high-yield CrIII μ3-methylidyne complex. Substitution of the terminal chlorido ligands via salt metathesis with alkali-metal cyclopentadienides generates isostructural half-sandwich chromium(III)-μ3-methylidynes [CpR3Cr3(μ2-Cl)3(μ3-CH)] (CpR=C5H5, C5Me5, C5H4SiMe3). Side and decomposition products of the Cl/CpR exchange reactions were identified and structurally characterized for [Cr4(μ2-Cl)4(μ2-I)2(μ4-O)(thf)4] and [(η5-C5H4SiMe3)CrCl(μ2-Cl)2Li(thf)2]. The Cl/CpR exchange drastically changed the ambient-temperature effective magnetic moment μeff from 9.30/9.11 μB (solution/solid) to 3.63/4.32 μB (CpR=C5Me5). Reactions of [Cr3Cl3(μ2-Cl)3(μ3-CH)(thf)6] with aldehydes and ketones produce intricate mixtures of species through oxy/methylidyne exchange, which were partially identified as radical recombination products through GC/MS analysis and 1H NMR spectroscopy.
A Rare-Earth-Metal Ensemble of the Tebbe Reagent: Scope of Coligands and Carbonyl Olefination
Anwander, Reiner,Birkelbach, Verena M.,Dietrich, H. Martin,Kracht, Felix,Maichle-M?ssmer, C?cilia,Stuhl, Christoph
, p. 3490 - 3504 (2020/10/09)
Treatment of the half-sandwich complexes CpRLn(AlMe4)2 (CpR = C5Me5, C5Me4SiMe3; Ln = Y, La, Lu) with the mild halogenido transfer reagents SiMe3X (X = Cl, Br, I) resulted in efficient and selective halogenido/tetramethylaluminato exchange. Depending on the size of the rare-earth metal, dimeric [CpRLn(AlMe4)(μ-X)]2 (Ln = Y, Lu) and decametallic [CpR3La3(AlMe4)2(μ-X)4]2 could be obtained. Donor (THF)-induced tetramethylaluminato cleavage gave access to methyl-free mixed methylidene/halogenido complexes CpR3Ln3(μ-X)3(μ3-X)(μ3-CH2)(THF)3 for yttrium (X = Cl, Br) and lanthanum (X = Cl, Br, I) in good yields. Additionally, mixed methylidene/halogenido Y(III) complexes could be obtained via methyl/halogenido exchange employing (C5Me5)3Y3(μ-Me)3(μ3-Me)(μ3-CH2)(THF)2 and SiMe3X via tetramethylsilane elimination. All methylidene complexes were probed in olefination reactions and found to act as efficient Schrock-type nucleophilic carbenes converting ketones and aldehydes into the respective terminal alkenes. Such reactivity is as high as that of the prominent Tebbe reagent but is less tolerant toward sterically demanding and functionalized substrates (such as esters). In contrast to the Tebbe reagent, complexes CpR3Ln3(μ-X)3(μ3-X)(μ3-CH2)(THF)3 polymerize δ-valerolactone in an efficient manner, generating polylactones with molecular weight distributions Mw/Mn as low as 1.13. Moreover, the bromido variant of the Tebbe reagent, Cp2Ti(μ-CH2)(μ-Br)AlMe2, is described, underlying similar synthesis limitations: that is, the coformation (and hence cocrystallization) of the trivalent species Cp2Ti(μ-Br)2AlMe2.
