- Zinc(II)-Mediated Carbene Insertion into C-H Bonds in Alkanes
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The cationic zinc adduct {[HB(3,5-(CF3)2Pz)3]Zn(NCMe)2}ClO4 catalyzes the functionalization of tertiary, secondary, and primary C-H bonds of alkanes via carbene insertion. Ethyl diazoacetate serves as the:CHCO2Et carbene precursor. The counteranion, supporting ligand, and coordinating solvents affect the catalytic activity. An in situ generated {[HB(3,5-(CF3)2Pz)3]Zn}+ species containing a bulkier {B[3,5-(CF3)2C6H3]4}- anion gives the best results among the zinc catalysts used.
- Kulkarni, Naveen V.,Dash, Chandrakanta,Jayaratna, Naleen B.,Ridlen, Shawn G.,Karbalaei Khani, Sarah,Das, Animesh,Kou, Xiaodi,Yousufuddin, Muhammed,Cundari, Thomas R.,Dias, H. V. Rasika
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supporting information
p. 11043 - 11045
(2015/12/17)
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- A fully recyclable heterogenized Cu catalyst for the general carbene transfer reaction in batch and flow
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A polystyrene-linked tris(triazolyl)methanecopper(i) cationic catalyst operates under heterogeneous conditions for the reaction of ethyl diazoacetate (EDA) with an array of substrates. Carbon-hydrogen as well as X-H (X = O, N) functionalization derived from the formal transfer of the carbene moiety (:CHCO2Et) from the copper center and subsequent insertion have been achieved, the reactions permitting repeated catalyst recycling and reuse. The addition of the same carbene unit to benzene leading to a cycloheptatriene derivative (Büchner reaction) or to phenylacetylene (cyclopropenation) took place at similar rates to the insertion processes and with the same catalyst recyclability. The use of this heterogenized cationic Cu catalyst in continuous flow has also been implemented. Key characteristics of the flow process are its high and constant turnover frequency (TOF) (residence times of 1 min still lead to full conversion in the reaction with ethanol after 48 h operation) and its suitability for the sequential performance of different types of carbene transfer reactions with a simple and affordable experimental setup.
- Maestre, Lourdes,Ozkal, Erhan,Ayats, Carles,Beltrn, lvaro,Daz-Requejo, M. Mar,Prez, Pedro J.,Perics, Miquel A.
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p. 1510 - 1515
(2015/02/05)
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- TBAF-catalyzed cyclization of 6-hydroxyhex-2-ynoates and 7-hydroxyhept-2-ynoates
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Tetrabutyl ammonium fluoride (TBAF) was found to be capable of catalyzing the intramolecular hydroalkoxylation of 6-hydroxyhex-2-ynoates and 7-hydroxyhept-2-ynoates. The reaction could be used to prepare 2,5-substituted THF rings and 2,6-substituted THP rings.
- Wang, Xiao Qing,Jia, Ping Jing,Liu, Su Ping,Yu, Wei
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p. 931 - 934
(2012/01/11)
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- Heterogeneous catalysts for carbene insertion reactions
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Copper catalysts supported on silica or silica-alumina are used to promote the insertion of carbenes, coming from methyl phenyldiazoacetate and ethyl diazoacetate, into one C-H bond of THF, constituting the first example of this reaction promoted by a pur
- Fraile, Jose M.,Mayoral, Jose A.,Ravasio, Nicoletta,Roldan, Marta,Sordelli, Laura,Zaccheria, Federica
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experimental part
p. 273 - 278
(2011/09/21)
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- Synthesis of new copper(i) complexes with tris(2-pyridyl) ligands. Applications to carbene and nitrene transfer reactions
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New copper(i) complexes with tris(2-pyridyl)methane (TPC), tris(2-pyridyl)methoxymethane (TPM) and tris(2-pyridyl)amine (TPN) ligands have been synthesized and characterized, including structural determinations by X-ray diffraction of some examples. Their activity as catalysts in carbene and nitrene transfer reactions was studied.
- Perez, Julio,Morales, Dolores,Garcia-Escudero, Luis A.,Martinez-Garcia, Hector,Miguel, Daniel,Bernad, Pablo
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experimental part
p. 375 - 382
(2009/04/14)
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- Synthesis of (tetrahydrofuran-2-yl)acetates based on a 'cyclization/hydrogenation/enzymatic kinetic resolution' strategy
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A variety of (tetrahydrofuran-2-yl)acetates and (pyrrolidin-2-yl)acetates have been prepared by hydrogenation of 2-alkylidenetetrahydrofurans and 2-alkylidenepyrrolidines, which are readily available by cyclization reactions of 1,3-dicarbonyl dianions ('free dianions') or 1,3-bis-silyl enol ethers ('masked dianions') with 1,2-dielectrophiles. The enzymatic kinetic resolution of (tetrahydrofuran-2-yl)acetates with recombinant esterase Est56 proceeded with excellent enantioselectivities (E>100).
- Bellur, Esen,Freifeld, Ilia,B?ttcher, Dominique,Bornscheuer, Uwe T.,Langer, Peter
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p. 7132 - 7139
(2007/10/03)
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- BENZO(5,6)CYCLOHEPTA(1,2-B)PYRIDINE DERIVATIVES USEFUL FOR INHIBITION OF FARNESYL PROTEIN TRANSFERASE
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Novel compounds of formula (1.0) are disclosed. In Formula (1.0) a represents N or NO, R and R are halo, R and R are independently H or halo provided that at least one is H, X is C, CH or N, and T represents a five or six membered heterocycloalkyl ring having one or two heteroatoms selected from S or O. Also disclosed are methods of inhibiting farnesyl protein transferase and methods for treating tumor cells.
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- Intermolecular copper-catalyzed carbon-hydrogen bond activation via carbene insertion
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A series of catalysts of general formula TpXCu (TpX = homoscorpionate ligand) promote the insertion of :CHCO2Et (ethyl diazoacetate as the carbene source) into the C-H bonds of cycloalkanes and cyclic ethers in moderate to high yield. A correlation between the steric hindrance of these catalysts and the yield of the transformation has been observed. Copyright
- Diaz-Requejo, M. Mar,Belderrain, Tomas R.,Nicasio, M. Carmen,Trofimenko, Swiatoslaw,Perez, Pedro J.
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p. 896 - 897
(2007/10/03)
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- Compounds useful for inhibition of farnesyl protein transferase
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Novel compounds of the formula: are disclosed. In Formula 1.0 a represents N or NO, R1and R3are halo, R2and R4are independently H or halo provided that at least one is H, X is C, CH or N, and T represents a five or six membered heterocycloalkyl ring having one or two heteroatoms selected from S or O. Also disclosed are methods of inhibiting farnesyl protein transferase and methods for treating tumor cells.
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- β-Alkoxyacrylates in radical cyclizations: Remarkably efficient oxacyle synthesis
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β-Alkoxyacrylates were found to be exceptionally efficient radical acceptors in radical-mediated intramolecular cyclizations. For example, reaction of 5-bromo-2-pentanol with ethyl propiolate, tributylstannane-mediated radical cyclization, and hydrolysis yielded (±) (cis-6-methyltetrahydropyran-2-yl)acetic acid, a known component of civet.
- Lee, Eun,Tae, Jin Sung,Lee, Chulbom,Park, Cheol Min
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p. 4831 - 4834
(2007/10/02)
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- A tandem ester cleavage-Michael addition reaction for the synthesis of oxygen heterocycles
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A tandem ester cleavage-Michael addition sequence has been developed for the preparation of five- and six-ring oxygen heterocycles bearing an acetic acid residue at C-2. Treatment of ethyl 6- or 7-acetyloxy-2-alkenoates with ethanolic sodium ethoxide affo
- Bunce,Bennett
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p. 1009 - 1020
(2007/10/02)
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- Deacyloxy-alkylation of 2-Acyloxy-tetrahydrofurans and -tetrahydropyrans by Reformatsky Reagents
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A novel type of Reformatsky reaction between 2-acetoxytetrahydrofuran derivatives, ethyl bromoacetate, and zinc affords ethyl(2-tetrahydrofuranyl)acetates in the presence of a small amount of TiCl4; this reaction is also applicable to 2-acetoxytetrahydrop
- Hayashi, Masahiko,Sugiyama, Motoyoshi,Toba, Taketo,Oguni, Nobuki
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p. 767 - 768
(2007/10/02)
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- Stereoselective Syntheses of α-Substituted Cyclic Ethers and syn-1,3-Diols
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In the presence of a catalytic amount of triphenylmethylium hexachloroantimonate or a catalyst system of antimony pentachloride, chlorotrimethylsilane and tin(II)iodide, α-substituted cyclic ethers are stereoselectively prepared from lactones by successiv
- Homma, Koichi,Takenoshita, Haruhiro,Mukaiyama, Teruaki
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p. 1898 - 1915
(2007/10/02)
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- Rhodium Acetate Catalyzes the Addition of Carbenoids α- to Ether Oxygens
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Diazo-carbonyl compounds, when catalyzed by rhodium acetate, insert preferentially adjacent to ether oxygens.This phenomenon was exploited to develop a synthesis of 3(2H)-furanones.
- Adams, Julian,Poupart, Marc-Andre,Grenier, Louis,Schaller, Chris,Ouimet, Nathalie,Frenette, Richard
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p. 1749 - 1752
(2007/10/02)
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- One-Pot Synthesis of α-Mono- and α,α-Disubstituted Cyclic Ethers from Lactones
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α-Mono- and α,α-disubstituted cyclic ethers are prepared in good yields by the successive treatment of lactones with t-butyldimethylsiloxy-1-ethoxyethene and silyl nucleophiles (triethylsilane, allyltrimethylsilane, trimethylsilyl cyanide, etc.) in the pr
- Mukaiyama, Teruaki,Homma, Koichi,Takenoshita, Haruhiro
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p. 1725 - 1728
(2007/10/02)
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