- Three-Fold Scholl-Type Cycloheptatriene Ring Formation around a Tribenzotriquinacene Core: Toward Warped Graphenes
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A nonplanar polycyclic aromatic compound 6 bearing a tribenzotriquinacene (TBTQ) core merged with an o,p,o,p,o,p-hexaphenylene belt was prepared and characterized by NMR spectroscopy and X-ray crystallography. The key synthesis step involves three Scholl-type cycloheptatriene ring formation steps of the 1,4,8-tris(3′,4′-dimethoxyphenyl)-TBTQ derivative 5. The bridging of each of the three TBTQ bays by 1,2-phenylene units in compound 6 gives rise to an unusual wizard hat shaped structure, which represents a promising key intermediate for the construction of nonplanar nanographene molecules bearing a TBTQ core.
- Ip, Ho-Wang,Ng, Chun-Fai,Chow, Hak-Fun,Kuck, Dietmar
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Read Online
- Bulky N-Heterocyclic-Carbene-Coordinated Palladium Catalysts for 1,2-Addition of Arylboron Compounds to Carbonyl Compounds
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The synthesis of primary, secondary, and tertiary alcohols by the 1,2-addition of arylboronic acids or boronates to carbonyl compounds, including unactivated ketones, using novel bulky yet flexible N-heterocyclic carbene (NHC)-coordinated 2,6-di(pentan-3-yl)aniline (IPent)-based cyclometallated palladium complexes (CYPs) as catalysts is reported. The PhS-IPent-CYP-catalyzed reactions are efficient at low catalyst loadings (0.02–0.3 mol% Pd), and the exceptional catalytic activity for 1,2-addition is attributed to the steric bulk of the NHC ligand. These reactions can yield a wide range of functionalized benzylic alcohols that are difficult to synthesize by classical protocols using highly active organomagnesium or lithium reagents.
- Okuda, Yuta,Nagaoka, Masahiro,Yamamoto, Tetsuya
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p. 6291 - 6300
(2020/11/30)
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- Asymmetric Transfer Hydrogenation of o-Hydroxyphenyl Ketones: Utilizing Directing Effects That Optimize the Asymmetric Synthesis of Challenging Alcohols
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A systematic range of o-hydroxyphenyl ketones were reduced under asymmetric transfer hydrogenation conditions using the C3-tethered catalyst 2. Two directing effects, i.e., an o-hydroxyphenyl coupled to a bulky aromatic on the opposite side of the ketone substrate, combine in a matched manner to deliver reduction products with very high enantiomeric excess.
- Clarkson, Guy J.,Wills, Martin,Zheng, Ye
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supporting information
(2020/05/05)
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- Diaryl hydroxylamines as pan or dual inhibitors of indoleamine 2,3-dioxygenase-1, indoleamine 2,3-dioxygenase-2 and tryptophan dioxygenase
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Tryptophan (Trp) catabolizing enzymes play an important and complex role in the development of cancer. Significant evidence implicates them in a range of inflammatory and immunosuppressive activities. Whereas inhibitors of indoleamine 2,3-dioxygenase-1 (IDO1) have been reported and analyzed in the clinic, fewer inhibitors have been described for tryptophan dioxygenase (TDO) and indoleamine 2,3-dioxygenase-2 (IDO2) which also have been implicated more recently in cancer, inflammation and immune control. Consequently the development of dual or pan inhibitors of these Trp catabolizing enzymes may represent a therapeutically important area of research. This is the first report to describe the development of dual and pan inhibitors of IDO1, TDO and IDO2.
- Winters, Maria,DuHadaway, James B.,Pham, Khoa N.,Lewis-Ballester, Ariel,Badir, Shorouk,Wai, Jenny,Sheikh, Eesha,Yeh, Syun-Ru,Prendergast, George C.,Muller, Alexander J.,Malachowski, William P.
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supporting information
p. 455 - 464
(2018/11/25)
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- The cytochrome: C -cyclo[6]aramide complex as a supramolecular catalyst in methanol
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A hydrogen-bonded macrocycle, cyclo[6]aramide, was found to form a supramolecular complex with cytochrome c, which enables the solubilization of the heme protein in methanol. The supramolecular complexation was evidenced by UV-vis, CD, and Raman spectroscopic techniques via structural characterization. Computational simulation based on the DFT method reveals the presence of strong hydrogen bonds formed between the lysine residues exposed on the protein surface and the oxygen atoms residing in the cavity of cyclo[6]aramide apart from cation-π interactions. The resulting cytochrome c-cyclo[6]aramide 1 exhibited higher activities than unmodified cytochrome c in the oxidation of benzhydrol to benzophenone with hydrogen peroxide at low temperatures. The enhanced activity with lowering temperature up to -40 °C indicates that the complex can act as a "cold-active" synzyme. The results achieved here demonstrate the potential of hydrogen-bonded macrocycles in supramolecular chemistry for catalytic reactions via ligand-protein interactions.
- Pan, Wang,Mao, Lijun,Shi, Mingsong,Fu, Yonghong,Jiang, Xiaomin,Feng, Wen,He, Youzhou,Xu, Dingguo,Yuan, Lihua
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supporting information
p. 3857 - 3866
(2018/03/06)
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- Aminotriazole Mn(I) Complexes as Effective Catalysts for Transfer Hydrogenation of Ketones
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A catalytic system based on complexes comprising abundant and cheap manganese together with readily available aminotriazole ligands is reported. The new Mn(I) complexes are catalytically competent in transfer hydrogenation of ketones with 2-propanol as hydrogen source. The reaction proceeds under mild conditions at 80 °C for 20 h with 3 % of catalyst loading using either KOtBu or NaOH as base. Good to excellent yields were obtained for a wide substrate scope with broad functional group tolerance. The obtained results by varying the substitution pattern of the ligand are consistent with an out-sphere mechanism for the H-transfer.
- Martínez-Ferraté, Oriol,Werlé, Christophe,Franciò, Giancarlo,Leitner, Walter
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p. 4514 - 4518
(2018/10/20)
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- Grignard Reagents on a Tab: Direct Magnesium Insertion under Flow Conditions
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An on-demand preparation of organomagnesium reagents is presented using a new flow protocol. The risks associated with the activation of magnesium are circumvented by a new on-column initiation procedure. Required amounts of solutions with a precise titration were obtained. Telescoped flow or batch reactions allow access to a diverse set of functional groups.
- Huck, Lena,De La Hoz, Antonio,Díaz-Ortiz, Angel,Alcázar, Jesus
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supporting information
p. 3747 - 3750
(2017/07/26)
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- Newly synthesized furanoside-based NHC ligands for the arylation of aldehydes
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New furanoside-based NHC precursor salts (2) were synthesized using amino alcohols from the chloralose derivatives of glucose (a), galactose (b), and mannose (c). The novel compounds were fully characterized by 1H NMR, 13C NMR, and elemental analyses. The catalytic activities of these salts were tested in the arylation of aldehydes as catalysts that were generated in situ from [RhCl(COD)]2. In addition, 2a was converted to the rhodium complex 3a in order to compare the results obtained in situ. The newly synthesized compounds were very efficient in terms of yield; nevertheless they did not exhibit a chiral induction.
- Denizalti, Serpil,?etin Telli, Fatma,Yildiran, Selin,Salman, Azize Ye?im,?etinkaya, Bekir
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p. 689 - 697
(2016/11/09)
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- Exploring the Reactivity of α-Lithiated Aryl Benzyl Ethers: Inhibition of the [1,2]-Wittig Rearrangement and the Mechanistic Proposal Revisited
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By carefully controlling the reaction temperature, treatment of aryl benzyl ethers with tBuLi selectively leads to α-lithiation, generating stable organolithiums that can be directly trapped with a variety of selected electrophiles, before they can undergo the expected [1,2]-Wittig rearrangement. This rearrangement has been deeply studied, both experimentally and computationally, with aryl α-lithiated benzyl ethers bearing different substituents at the aryl ring. The obtained results support the competence of a concerted anionic intramolecular addition/elimination sequence and a radical dissociation/recombination sequence for explaining the tendency of migration for aryl groups. The more favored rearrangements are found for substrates with electron-poor aryl groups that favor the anionic pathway.
- Velasco, Rocío,Silva López, Carlos,Nieto Faza, Olalla,Sanz, Roberto
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p. 15058 - 15068
(2016/10/11)
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- Coupling of aromatic aldehydes with aryl halides in the presence of nickel catalysts with diazabutadiene ligands
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Nickel catalysts with diazabutadiene ligands promote cross-coupling of benzaldehydes with aryl halides in the presence of zinc as reducing agent, which leads to the corresponding benzhydrols and benzophenones. The benzophenone percentage considerably increases when lithium chloride additive is used.
- Asachenko,Valaeva,Kudakina,Uborsky,Izmer,Kononovich,Voskoboynikov
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p. 456 - 463
(2017/03/08)
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- The carbonyl group tuned electron-deficient phosphorus ligands and their application in Rhodium catalyzed arylation to aldehydes
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Acylphosphines, which could be efficiently prepared from acid chlorides and secondary phosphines, were developed as a type of carbonyl group tuned electron-deficient phosphorus ligand. They were found to be a kind of efficient ligand in Rhodium catalyzed arylation to aldehydes through accelerating the transmetalation process. Chiral acylphosphine ligands could be generated from carboxylic acids bearing the chiral framework correspondingly.
- Yang, Jiefang,Chen, Xingyu,Wang, Zhiqian
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supporting information
p. 5673 - 5675
(2015/09/15)
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- Enantioselective addition of ArTi(OiPr)3 to aldehydes catalyzed by a titanium complex of an N-sulfonylated amino alcohol
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Asymmetric additions of ArTi(OiPr)3 to aldehydes catalyzed by a titanium catalyst of N-sulfonylated amino alcohols were reported, and results showed that the chiral N-sulfonylated amino alcohol with two stereogenic centers could catalyze the asymmetric addition of ArTi(OiPr)3 to aldehydes to afford desired secondary alcohols in good yields with good to excellent enantioselectivities of up to 95% ee.
- Chang, Shih-Ju,Zhou, Shuangliu,Gau, Han-Mou
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p. 9368 - 9373
(2015/02/19)
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- UV light-mediated difunctionalization of alkenes through aroyl radical addition/1,4-/1,2-Aryl shift cascade reactions
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UV light-mediated difunctionalization of alkenes through an aroyl radical addition/1,4-/1,2-aryl shift has been described. The resulted aroyl radical from a photocleavage reaction added to acrylamide compounds followed by cyclization led to the formation of oxindoles, whereas the addition to cinnamic amides aroused a unique 1,4-aryl shift reaction. Furthermore, the difunctionalization of alkenes of prop-2-en-1-ols was also achieved through aroyl radical addition and a sequential 1,2-aryl shift cascade reaction.
- Zheng, Lewei,Huang, Hongli,Yang, Chao,Xia, Wujiong
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supporting information
p. 1034 - 1037
(2015/03/30)
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- Palladium-catalyzed arylation of aldehydes with bromo-substituted 1,3-diaryl-imidazoline carbene ligand
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The combination of 0 valent palladium precursor and bromo-substituted 1,3-diaryl-imidazoline carbene ligand precursor such as 1-(2-bromophenyl)-3-(2,6-diisopropylphenyl)-imidazolinium chloride 1a exhibited high catalytic activity for the 1,2-addition of arylboronic acids to aldehydes including aqueous formaldehyde.
- Yamamoto, Tetsuya,Furusawa, Takuma,Zhumagazin, Azamat,Yamakawa, Tetsu,Oe, Yohei,Ohta, Tetsuo
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- Chelating alkoxy NHC-Rh(I) complexes and their applications in the arylation of aldehydes
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In this study, new rhodium(I) complexes (5 and 6) have been prepared by the reaction of [RhCl(COD)]2 with a series of imidazolium salts (3 and 4), which were obtained from a chiral amino alcohol. The catalytic activities of these complexes were tested in the arylation of aldehydes. It was found that the synthesized rhodium complexes were highly effective catalysts for the arylation of aldehydes in short reaction times (5 min, TOF = 1193 h -1). However, the obtained ee values (up to 32% ee) remained low. We have proposed a mechanism for the arylation reaction of aldehydes, which is confirmed via 19F NMR spectroscopy.
- Denizalti, Serpil,Türkmen, Hayati,?etinkaya, Bekir
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supporting information
p. 4129 - 4132
(2014/07/22)
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- From in vitro to in cellulo: Structure-activity relationship of (2-nitrophenyl)methanol derivatives as inhibitors of PqsD in Pseudomonas aeruginosa
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Recent studies have shown that compounds based on a (2-nitrophenyl)methanol scaffold are promising inhibitors of PqsD, a key enzyme of signal molecule biosynthesis in the cell-to-cell communication of Pseudomonas aeruginosa. The most promising molecule displayed anti-biofilm activity and a tight-binding mode of action. Herein, we report on the convenient synthesis and biochemical evaluation of a comprehensive series of (2-nitrophenyl)methanol derivatives. The in vitro potency of these inhibitors against recombinant PqsD as well as the effect of selected compounds on the production of the signal molecules HHQ and PQS in P. aeruginosa were examined. The gathered data allowed the establishment of a structure-activity relationship, which was used to design fluorescent inhibitors, and finally, led to the discovery of (2-nitrophenyl)methanol derivatives with improved in cellulo efficacy providing new perspectives towards the application of PqsD inhibitors as anti-infectives. This journal is the Partner Organisations 2014.
- Storz, Michael P.,Allegretta, Giuseppe,Kirsch, Benjamin,Empting, Martin,Hartmann, Rolf W.
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supporting information
p. 6094 - 6104
(2014/08/05)
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- Synthesis of Ar-BINMOL ligands by [1,2]-wittig rearrangement to probe their catalytic activity in 1,2-addition reactions of aldehydes with Grignard reagents
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We have demonstrated a highly diastereoselective synthesis of optically pure Ar-BINMOL-derived diols and their analogues. The present study demonstrates a unique cascade chirality transfer in a [1,2]-Wittig rearrangement that leads to chiral diols with three stereogenic centers, which include a chiral sp 3 center at the alcohol and C2-axial chirality. Screening these ligands in the arylation of aromatic aldehydes with Grignard reagents shows that the naphthyl-substituted BINMOL promotes the aryl transfer reaction in good yields (70-92 %) and moderate-to-good enantioselectivities (up to 72 % ee), and a series of control experiments substantiates that the axial chirality and the chiral sp3 center at the alcohol of the Ar-BINMOLs are the pivotal enantioselectivity-controlling structure elements. In addition, this study demonstrated the importance of the chiral sp3 center at the alcohol on Ar-BINMOL for the aryl transfer reaction. Finally, we found that the chiral Ar-BINMOL ligand 2h mediated the titanium-promoted 1,2-addition of MeMgBr to aldehydes to give the desired products in good yields with excellent enantioselectivities (up to 92 % ee). Ar-BINMOL ligands: A new diastereoselective synthesis of optically pure Ar-BINMOL-derived diols and their analogues has been established through cascade chirality transfer of a [1,2]-Wittig rearrangement. The axial and sp3 central chirality of Ar-BINMOLs are the pivotal enantioselectivity-controlling structure elements in the 1,2-addition of aldehydes with Grignard reagents. Copyright
- Zheng, Long-Sheng,Jiang, Ke-Zhi,Deng, Yuan,Bai, Xing-Feng,Gao, Guang,Gu, Feng-Lei,Xu, Li-Wen
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p. 748 - 750
(2013/03/28)
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- Dehydrative fragmentation of 5-hydroxyalkyl-1 h -tetrazoles: A mild route to alkylidenecarbenes
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The development of a mild, base-free method for the generation of alkylidenecarbenes is reported. Treatment of 5-hydroxyalkyl-1H-tetrazoles with carbodiimides generates products arising from the 1,2-rearrangement or [1,5]-C-H bond insertion of a putative alkylidenecarbene. Formation of this divalent intermediate is proposed to occur by way of a tetraazafulvene, which undergoes extrusion of 2 mol of dinitrogen. Details of this methodology, its application to the synthesis of combretastatin A-4, and an improved route to 5-hydroxyalkyl-1H-tetrazoles are described.
- Wardrop, Duncan J.,Komenda, John P.
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supporting information; body text
p. 1548 - 1551
(2012/06/05)
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- Microwave-assisted nickel(II) acetylacetonate-catalyzed arylation of aldehydes with arylboronic acids
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Applying sealed vessel microwave heating at 180 °C in toluene the arylation of aromatic and aliphatic aldehydes with arylboronic acids using 1-2 mol % of Ni(acac)2 as a catalyst can be performed efficiently within 10-30 min providing the desired diarylmethanols or benzyl alcohols in good yields.
- Chen, Wen,Baghbanzadeh, Mostafa,Kappe, C. Oliver
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experimental part
p. 1677 - 1679
(2011/04/25)
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- A simple procedure for the polymer-supported N-heterocyclic carbene-rhodium complex via click chemistry: A recyclable catalyst for the addition of arylboronic acids to aldehydes
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A novel polymer-supported carbene-rhodium complex was prepared using a simple procedure via click chemistry. This polymer-supported N-heterocyclic carbene-rhodium complex was characterized and used as a catalyst for the addition of arylboronic acids to aldehydes in good to excellent yields.
- He, Ying,Cai, Chun
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supporting information; experimental part
p. 12319 - 12321
(2011/12/15)
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- Ni(COD)2/4-ClC6H4COR-catalyzed addition reactions of arylboroxines with aldehydes
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Ni(COD)2/4-ClC6H4COR (R = H, CH3, Ph) was found to be an efficient catalyst system for the addition reactions of arylboroxines with aromatic and aliphatic aldehydes. The catalytically active species for Ni(COD)2/4-ClC6H4COR catalyst systems was likely to be their oxidative addition adducts, 4-RCOC6H4Ni(II)Cl(COD) complexes.
- Xing, Chun-Hui,Hu, Qiao-Sheng
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supporting information; experimental part
p. 924 - 927
(2010/05/18)
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- Discovery of novel and potent benzhydryl-tropane trypanocides highly selective for Trypanosoma cruzi
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A benzhydryl tropinone oxime that is potently toxic to Trypanosoma cruzi has been previously identified. An SAR investigation determined that no part of the original compound was superfluous and all early SAR probes led to significant drops in activity. The only alteration that could be achieved without loss of activity was replacement of the aryl chloride substituent with chloro homologues. This led to the discovery of a trifluoromethyl-containing analogue with an EC50 against T. cruzi of 30 nM and a cytotoxicity selectivity index of over 1000 relative to rat skeletal myoblast L-6 cells.
- Holloway,Parisot,Novello,Watson,Armstrong,Thompson,Street,Baell
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supporting information; experimental part
p. 1816 - 1818
(2010/06/21)
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- Palladium catalyzed isomerization of alkenes: A pronounced influence of an o-phenol hydroxyl group
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A novel palladium catalyzed isomerization of alkenes has been found, where an ortho-phenol hydroxyl group has a pronounced influence on the isomerization.
- Fan, Jinmin,Wan, Changfeng,Wang, Qiang,Gao, Linfeng,Zheng, Xiaoqi,Wang, Zhiyong
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supporting information; experimental part
p. 3168 - 3172
(2011/02/25)
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- A new route to acyclic diaminocarbenes via lithium-halogen exchange
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A lithium - halogen exchange route has been developed to generate acyclic diaminocarbenes (ADC) from chloroamidinium salts. Convenient access to various ADC complexes (B, Rh, lr, Pd) stems from a one-pot transmetalation protocol. Formation of a carbenoid species is suggested by 1D and 2D NMR studies with a 13C-labeled chloroamidinium precursor and also by X-ray structures of transition metal-carbene complexes. Rh-ADC complex 4 is an effective catalyst for the 1,2-addition of aryl boronic acids to aryl aldehydes.
- Snead, David R.,Ghiviriga, Ion,Abboud, Khalil A.,Hong, Sukwon
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supporting information; experimental part
p. 3274 - 3277
(2009/12/01)
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- Nickel salt-catalyzed addition reaction of arylboronic acids to aromatic aldehydes
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Arylation reaction of aromatic aldehydes with arylboronic acids proceeded smoothly in the presence of a base and catalytic amount of a nickel salt, Ni(ClO4)2·6H2O, in toluene/IPA = 5:1 or IPA to afford corresponding diarylmethanols in good to excellent yields.
- Zhou, Li,Du, Xin,He, Ren,Ci, Zhenhua,Bao, Ming
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scheme or table
p. 406 - 408
(2009/05/11)
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- Addition reaction of arylboronic acids to aldehydes and α,β-unsaturated carbonyl compounds catalyzed by conventional palladium complexes in the presence of chloroform
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Arylboronic acids react with aldehydes and α,β-unsaturated carbonyl compounds in the presence of a base and a catalytic amount of a palladium(0) complex with chloroform, affording the corresponding addition products in good yields, and chiral benzhydrol was obtained with up to 43% e.e. using (S,S)-bppm as a ligand. General palladium complexes have no catalytic activity without chloroform. Because chloroform is essential for this reaction, these reactions would be promoted by dichloromethylpalladium(II) species.
- Yamamoto, Tetsuya,Iizuka, Michiko,Takenaka, Hiroto,Ohta, Tetsuo,Ito, Yoshihiko
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experimental part
p. 1325 - 1332
(2009/09/28)
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- Cyclopalladated complexes catalyzed addition of arylboronic acids to aldehydes in neat water
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Cyclopalladated ferrocenylimine complexes gave high yields for the addition of arylboronic acids with aldehydes in neat water using a weak acid as additive.
- Yu, Ajuan,Cheng, Baoli,Wu, Yangjie,Li, Jingya,Wei, Kun
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p. 5405 - 5407
(2008/12/21)
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- Development of asymmetric nickel-catalyzed arylation of aromatic aldehydes with arylboron reagents
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The development of the nickel-catalyzed 1,2-addition of triarylboroxins to aromatic aldehydes in the presence of a phosphine ligand is described. This development allowed the asymmetric nickel-catalyzed 1,2-addition of arylboron reagents to aromatic aldehydes. The enantioselectivity is synthetically acceptable (up to 81 % ee) using 1-naphthaldehyde and 2-substituted aromatic aldehydes as substrates. The results have enantioselectivity comparable to the best results reported by us for the rhodium-catalyzed arylation of aromatic aldehydes. Georg Thieme Verlag Stuttgart · New York.
- Yamamoto, Kana,Tsurumi, Kaori,Sakurai, Fumie,Kondo, Kazuhiro,Aoyama, Toyohiko
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experimental part
p. 3585 - 3590
(2009/06/18)
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- Palladium-catalyzed 1,2-addition of potassium aryl- and alkenyltrifluoroborates to aldehydes using thioether-imidazolinium carbene ligands
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(Chemical Equation Presented) Palladium-catalyzed 1,2-addition of potassium aryl- and alkenyltrifluoroborates to aldehydes using thioether- imidazolinium carbene ligands proceeded readily under aqueous conditions. This process tolerated a diverse range of potassium trifluoroborate salts and aldehydes, giving a variety of carbinol derivatives with good to excellent yields.
- Kuriyama, Masami,Shimazawa, Rumiko,Enomoto, Terumichi,Shirai, Ryuichi
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p. 6939 - 6942
(2008/12/22)
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- Anionic four-electron donor-based palladacycles as catalysts for addition reactions of arylboronic acids with α,β-unsaturated ketones, aldehydes, and α-ketoesters
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(Chemical Equation Presented) Anionic four-electron donor-based palladacycle-catalyzed 1,4-additions of arylboronic acids with α,β-unsaturated ketones and 1,2-additions of arylboronic acids with aldehydes and α-ketoesters are described. Our study demonstrated that palladacycles were highly efficient, practical catalysts for these addition reactions. The work described here not only opened a new paradigm for the application of palladacycles, but may also pave the road for other metalacycles as practically useful catalysts for such addition reactions including asymmetric ones.
- He, Ping,Lu, Yong,Dong, Cheng-Guo,Hu, Qiao-Sheng
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p. 343 - 346
(2007/10/03)
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- Phosphinite- and phosphite-based type I palladacycles as highly active catalysts for addition reactions of arylboronic acids with aldehydes, α,β-unsaturated ketones, α-ketoesters, and aldimines
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Phosphinite- and phosphite-based type I palladacycle-catalyzed additions of arylboronic acids with aldehydes, α,β-unsaturated ketones, α-ketoesters, and aldimines are described. Our study showed that readily available phosphinite- and phosphite-based type I palladacycles could possess higher catalytic activity than phosphine-based palladacycles and were highly active, practical catalysts. Our study may pave the road for development of optically active phosphinite- and phosphite-based palladacycles for asymmetric catalysis.
- He, Ping,Lu, Yong,Hu, Qiao-Sheng
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p. 5283 - 5288
(2008/02/09)
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- Nickel-catalyzed 1,2-addition of arylboroxines to aromatic aldehydes
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Development of Ni-Et-Duphos-catalyzed 1,2-addition of arylboroxines to aromatic aldehydes is described. The dramatic effect of boron reagent and phosphine ligand is observed. This method with a phosphine ligand allows asymmetric arylation of aromatic aldehydes (up to 78% ee).
- Arao, Takafumi,Kondo, Kazuhiro,Aoyama, Toyohiko
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p. 4115 - 4117
(2008/02/03)
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- Use of cheaper metal than Rh, CHCl3-free Pd catalyst, in 1,2-addition of aromatic aldehydes with arylboronic acids
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Pd(OAc)2-(±)-tol-BINAP-catalyzed arylation reaction of aromatic aldehydes with arylboronic acids in the absence of CHCl3 is described.
- Suzuki, Kiyoto,Arao, Takafumi,Ishii, Satoru,Maeda, Yuka,Kondo, Kazuhiro,Aoyama, Toyohiko
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p. 5789 - 5792
(2007/10/03)
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- Asymmetric induction during electron transfer mediated photoreduction of carbonyl compounds: Role of zeolites
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Photochemistry of 17 aryl alkyl ketones included within cation exchanged zeolites has been examined. In solution five of the 17 ketones undergo intramolecular hydrogen abstraction reaction even in the presence of a chiral amine and the rest are photoreduced to the corresponding alcohol. Within zeolites all 17 ketones yielded in presence of a chiral amine, the corresponding alcohol as the major product. When a chiral amine was used as the coadsorbent within alkali ion exchanged zeolites, enantiomerically enriched alcohol was formed in all cases. The best chiral induction was obtained with phenyl cyclohexyl ketone (enantiomeric excess: 68%). 1H-13C Cross Polarization Magic Angle Spinning (CP-MAS) experiments, with a model ketone (perdeuterated acetophenone) and chiral amine (pseudoephedrine) included within MY zeolites, suggested that the cation brings the reactant and the chiral amine closer. The role of the cation in such a process is also revealed by the computation results. The results presented here highlight the importance of a supramolecular structure in forcing a closer interaction between a reactant and a chiral inductor that could be used to achieve asymmetric induction in photoproducts. The Royal Society of Chemistry 2006.
- Shailaja,Kaanumalle, Lakshmi S.,Sivasubramanian, Karthikeyan,Natarajan, Arunkumar,Ponchot, Keith J.,Pradhan, Ajit,Ramamurthy
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p. 1561 - 1571
(2008/02/03)
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- Method of preparing organomagnesium compounds
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The present invention is directed to a reagent for use in the preparation of organomagnesium compounds as well as to a method of preparing such organomagnesium compounds. The present invention furthermore provides a method of preparing functionalized or unfunctionalized organic compounds as well as the use of the reagents of the present invention in the preparation of organometallic compounds and their reaction with electrophiles. Finally, the present invention is directed to the use of lithium salts - LiY in the preparation of organometallic compounds and their reactions with electrophiles and to an organometallic compound which is obtainable by the disclosed method.
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Page/Page column 13
(2010/02/14)
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- Palladium-catalyzed addition of arylboronic acids to aldehydes
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(Chemical Equation Presented) Arylboronic acids react with aldehydes in the presence of a base and a catalytic amount of a palladium(0) complex with chloroform, affording the corresponding secondary alcohols in good yields. General palladium complexes have no catalytic activity without chloroform. Chloroform is essential for this reaction, and palladium complex that was prepared from Pd(PPh3)4 with CHCl3 showed good catalytic acitivty as well.
- Yamamoto, Tetsuya,Ohta, Tetsuo,Ito, Yoshihiko
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p. 4153 - 4155
(2007/10/03)
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- Carbinol derivatives via rhodium-catalyzed addition of potassium trifluoro(organo)borates to aldehydes
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Reaction of potassium aryltrifluoroborates with aldehydes, in the presence of a rhodium catalyst, afforded carbinol derivatives in high yields under mild aqueous conditions; this efficient reaction proved to be general, allowing the production of highly hindered diarylmethanols and aliphatic aldehydes were also reactive under these conditions. The Royal Society of Chemistry 2005.
- Pucheault, Mathieu,Darses, Sylvain,Genet, Jean-Pierre
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p. 4714 - 4716
(2007/10/03)
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- Microwave irradiation as a high-speed tool for activation of sluggish aryl chlorides in Grignard reactions
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Grignard reagents have been generated from reluctant aryl chlorides and bromides using controlled microwave heating to establish a safe, productive and reproducible method. In the synthesis of a novel HIV-1 protease inhibitor, microwave irradiation was both used to generate the starting arylmagnesium halide and to promote a subsequent Kumada coupling. Georg Thieme Verlag Stuttgart.
- Gold, Henrik,Larhed, Mats,Nilsson, Peter
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p. 1596 - 1600
(2007/10/03)
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- Scope of enantioselective Palladium(II)-catalyzed aerobic alcohol oxidations with (-)-sparteine
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Evaluation of the substrate scope for Pd(II)/ (-)-sparteine catalyzed aerobic oxidative kinetic resolution of secondary alcohols is disclosed. An improved system is found with use of tert-butyl alcohol solvent in which benzylic and aliphatic alcohols as well as alcohols containing olefins are effectively oxidatively resolved. For substrates that successfully undergo oxidative kinetic resolution, krel values are generally between 10 and 20. Successful scale-up of various substrates to 10-mmol scale is described. Extension to oxidative desymmetrization of 1,3-meso-diols is successful with enantiomeric excesses ranging from 78 to 85%.
- Mandal, Sunil K.,Jensen, David R.,Pugsley, Jacob S.,Sigman, Matthew S.
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p. 4600 - 4603
(2007/10/03)
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- Rhodium-catalyzed addition of arylstannanes to carbon-heteroatom double bond
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The addition of arylstannanes to the carbon-heteroatom double bond in the presence of a catalytic amount of a cationic rhodium complex ([Rh(cod)(MeCN)2]BF4) was examined. The reactions of aldehydes, α-dicarbonyl compounds, and N-substituted aldimines with the arylstannanes gave corresponding alcohols, α-hydroxy carbonyl compounds, and amines, respectively. An arylrhodium complex generated by the transmetalation with the arylstannane was probably the active catalytic species.
- Oi, Shuichi,Moro, Mitsutoshi,Fukuhara, Hiroe,Kawanishi, Takanori,Inoue, Yoshio
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p. 4351 - 4361
(2007/10/03)
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- Selective halogen - Magnesium exchange reaction via organomagnesium ate complex
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Halogen-magnesium exchange of various aryl halides is achieved with a magnesium ate complex at low temperatures. Tributylmagnesate (nBu3MgLi) induces facile iodine-magnesium exchange at -78 °C. Dibutylisopropylmagnesate (iPrnBu2MgLi) is more reactive than nBu3MgLi, and this reagent accomplishes selective bromine-magnesium exchange at -78 °C. This procedure is utilized for the preparation of various polyfunctionalized arylmagnesium species. The exchange of alkenyl halides using this method proceeds with retention of configuration of the double bond.
- Inoue,Kitagawa,Shinokubo,Oshima
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p. 4333 - 4339
(2007/10/03)
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- An electrochemical coupling of organic halide with aldehydes, catalytic in chromium and nickel salts. the Nozaki-Hiyama-Kishi reaction.
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[reaction: see text] Electrochemical arylation of arenecarboxaldehydes using an iron sacrificial anode in the presence of chromium and nickel catalysts afforded the corresponding arylated secondary alcohols in moderate to good yields. The chromium and nickel salts as catalysts are obtained by oxidation of a stainless steel rod during a preelectrolysis in 7% and 3%, respectively. The process was also applied to the addition of vinyl halide, allyl acetate, or alpha-chloroester to aromatic aldehydes.
- Durandetti,Nedelec,Perichon
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p. 2073 - 2076
(2007/10/03)
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- Electroreductive coupling of organic halides with aldehydes catalyzed by nickel(0) complex with 2,2′-bipyridine
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A method of electrosynthesis of secondary alcohols from aldehydes and organic halides under the action of nickel(0) complexes is proposed. The key stage is addition of σ-complex RNi(I)bipy (bipy is 2,2′-bipyridine) to the aldehyde group.
- Budnikova,Keshner,Kargin
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p. 453 - 456
(2007/10/03)
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- Ni(II)/Zn-mediated chemoselective arylation of aromatic aldehydes: Facile synthesis of diaryl carbinols
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(equation presented) Direct arylation of aromatic aldehydes with aryl bromides in the presence of Ni(II)Zn was investigated. The choice of ligand in this nickel-catalyzed coupling was critical to the formation of the secondary alcohols. Monodentate phosphine ligands were ineffective, whereas NiBr2-(dppe)/Zn successfully catalyzed this reductive coupling reaction. The reaction were mild and diarylcarbinols with a variety of functional groups such as ketone, ester, amide, and nitrile groups were readily prepared.
- Majumdar, Kanak Kanti,Cheng, Chien-Hong
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p. 2295 - 2297
(2007/10/03)
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- A novel carbon leaving group in the reaction of organometallic compounds with phosphine oxides
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The reaction of diphenyl(methoxymethyl)phosphine oxide 1 with organometallic reagents was found to lead to substitution of the methoxymethyl group. The P-phenyl substituent showed a lower propensity to undergo a displacement.
- Cardellicchio, Cosimo,Fracchiolla, Giuseppe,Naso, Francesco,Tortorella, Paolo,Holody, Wieslawa,Michal Pietrusiewicz
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p. 5773 - 5776
(2007/10/03)
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- Nickel- and chromium-catalysed electrochemical coupling of aryl halides with arenecarboxaldehydes
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Electrochemical arylation of arenecarboxaldehydes using a stainless steel sacrificial anode in the presence of Ni catalysts afforded the corresponding arylated secondary alcohols in good yields.
- Durandetti, Muriel,Perichon, Jacques,Nedelec, Jean-Yves
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p. 9009 - 9013
(2007/10/03)
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- Photocyclization Reactions. Part 6 [1]. Solvent and Substituent Effects in the Synthesis of Dihydrobenzofuranols Using Photocyclization of 2-Alkoxybenzophenones and Ethyl 2-Benzoylphenoxyacetates
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Photocyclization reactions were carried out on 2-alkoxybenzophenones 1a-h and ethyl 2-benzoylphenoxyacetates 5a-e in three solvents of different polarity (benzene, acetonitrile and methanol) to examine solvent and substituent effects on the cyclization of 1,5-biradical intermediates to dihydrobenzofuranols. Irradiation of 1a-f in benzene gave dihydrobenzofuranols 4a-f in 80-94% yields. The ratios of cis-and trans-isomers of 4b-f were 12:1 to 1:0, showing stereoselective formation of cis-isomers. On the other hand, irradiation of 1a-f in acetonitrile and methanol gave 4a-f in 68-81% and 7-75% yields, respectively. However, the ratios of cis- and trans-isomers of 4b-f were 3.5:1 to 1.3:1 in acetonitrile and 2.0:1 to 1:1.7 in methanol, showing decreased stereoselectivity. The decrease in stereoselectivity was attributed to intermolecular hydrogen bonding between the hydroxyl group of 1,5-biradicals and solvents (acetonitrile and methanol). Similarly, irradiation of 5a-e in benzene afforded cis-dihydrobenzofuranols cis-11a-e stereoselectively. In contrast, irradiation of 5a-e in acetonitrile and methanol gave a mixture of cis- and trans-isomers of 11a-e because of intermolecular hydrogen bonding between the hydroxyl group of 1,5-biradicals and solvents. The cis and Irons ratios of 11a-e varied from 1.5:1 to 17.8:1 in acetonitrile and from 2.6:1 to 1:4.5 in methanol. Solvent and substituent effects on the cyclization of 1,5-biradicals and reaction pathways are discussed.
- Sharshira, Essam Mohamed,Okamura, Mutsuo,Hasegawa, Eietsu,Horaguchi, Takaaki
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p. 861 - 869
(2007/10/03)
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- Lithium tri-tert-butylzincate as a chemoselective metallating reagent for functionalized organic halides
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Chemoselective metallation of functionalized organic halides has been performed under mild reaction conditions using a halogen-zinc exchange with lithium tri-tert-butylzincate and subsequent transformation of the zincates has been investigated.
- Kondo, Yoshinori,Fujinami, Michihiko,Uchiyama, Masanobu,Sakamoto, Takao
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p. 799 - 800
(2007/10/03)
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- Asymmetric Reduction of ortho-Substituted Benzophenones with B-Chlorodiisopinocampheylborane: A Convenient Synthesis of Enantiomerically Enriched Benzhydrols
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A very efficient synthesis of chiral benzhydrols from ortho-substituted benzophenones is described which presumably utilizes a heteroatom-directed, intramolecular asymmetric reduction of ketones with B-chlorodiisopinocampheylborane.
- Shieh, Wen-Chung,Cantrell, William R.,Carlson, John A.
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p. 3797 - 3800
(2007/10/02)
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- Behavior and extension of the scope of NADH models to the reduction of non-activated ketones by a stable indolo NADH model compound in the presence of Lewis acids
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The reduction of non-activated ketones, eg, acetophenone, by a very stable NADH model in the presence of Lewis acids (AlX3, Et2AlCl) is reported.During the reaction, a side equilibrated aldol condensation occurs.Due to the reversibility of this reaction, the overall yield in alcohol is not notably diminished.The scope of NADH models has been extended for the first time to non-activated ketones, such as dialkyl, aryl alkyl and diaryl ketones. - Keywords: NADH model / ketone reduction / Lewis acids / aldol condensation
- Berkous, Rabia,Dupas, Georges,Bourguignon, Jean,Queguiner, Guy
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p. 632 - 635
(2007/10/02)
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