- Structure-based screening and optimization of cytisine derivatives as inhibitors of the menin-MLL interaction
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The natural product-like compound 1 was identified as a direct inhibitor of the menin-MLL interaction by in silico screening. Structure-based optimization furnished analogue 1a, which showed significantly higher potency than both the lead structure 1 and the reference compound MI-2.
- Zhong, Hai-Jing,Lee, Bo Ra,Boyle, Joshua William,Wang, Wanhe,Ma, Dik-Lung,Hong Chan, Philip Wai,Leung, Chung-Hang
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Read Online
- An activity scale of cathode materials for the electrochemical cyclisation of allyl 2-bromobenzyl ether
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The electrocatalytic activity of 10 cathode materials (Ag, Au, Cu, Glassy carbon (GC), Ni, Mg, Mn, Pb, Pt and Ti) was examined for the intramolecular cyclisation reaction of allyl 2-bromobenzyl ether to 2-methyl benzopyran. The influence of the cathode materials on the electrocatalytic activity was tested by means of cyclic voltammetry (CV) in an electrolyte solution of allyl 2-bromobenzyl ether (1?mM) + tetrabutylammonium perchlorate (0.1?M) (Bu4NClO4) in methanol (MeOH). On Au, GC, Ni, Mg, Mn, Pb and Pt one single reduction wave was measured while Ag and Cu exhibited two cathodic reduction waves. Ti did not show a voltammetric response. The best electrocatalytic activity was obtained on Ag which showed a shift of the reduction peak potential of 771?mV with respect to GC, the most inert material. In addition to the screening, rotating disk experiments (RDE) in combination with Koutecky Levich analysis and product formation during electrosynthesis were performed. Koutecky Levich analysis of the RDE at peak potential showed that one-electron was transferred at Au, GC, Ni, Mg, Mn, Pb and Pt. On Ag and Cu the number of transferred electrons determined with Koutecky-Levich depends on the potential and can be tuned to specific one- or two-electron transfer. Electrosynthesis showed that on Au, GC, Ni, Mg, Mn, Pb and Pt exclusively 5-methyl benzopyran was formed. On Ag and Cu product formation was depended on the potential and 2-methyl benzopyran and allyl benzyl ether (not cyclized product) were both formed.
- Vanrenterghem, Bart,Breugelmans, Tom
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Read Online
- CuH-Catalyzed Asymmetric Intramolecular Reductive Coupling of Allenes to Enones
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The CuH-catalyzed asymmetric intramolecular reductive coupling of allenes to enones is successfully realized, providing cis-hydrobenzofurans with promising yields and excellent enantioselectivities. Such brilliant enantioselectivities are partially contributed by CuH-catalyzed favorable kinetic resolution of the cyclization products. This protocol tolerates a broad range of functional groups, allowing for further construction of tricyclic and bridged-ring structures. Moreover, the meta-chiral functionalization of 4-substituted phenol and asymmetric dearomatization modification of phenol-contained bioactive molecules are also described.
- Tan, Yun-Xuan,Tang, Xiao-Qi,Liu, Ping,Kong, De-Shen,Chen, Ya-Li,Tian, Ping,Lin, Guo-Qiang
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Read Online
- One carbon homologation of halides to benzyl ethers
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The preparation of one carbon homologated benzyl ethers from alkyl and aromatic halides is reported. The coupling reaction is rapid and efficient at room temperature.
- Taber, Douglass F.,Paquette, Craig M.,Reddy, P. Ganapati
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Read Online
- Chiral Cyclic Aliphatic Linkers as Building Blocks for Selective Dopamine D2or D3Receptor Agonists
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Linkers are emerging as a key component in regulating the pharmacology of bitopic ligands directed toward G-protein coupled receptors (GPCRs). In this study, the role of regio- and stereochemistry in cyclic aliphatic linkers tethering well-characterized primary and secondary pharmacophores targeting dopamine D2 and D3 receptor subtypes (D2R and D3R, respectively) is described. We introduce several potent and selective D2R (rel-trans-16b; D2R Ki = 4.58 nM) and D3R (rel-cis-14a; D3R Ki = 5.72 nM) agonists while modulating subtype selectivity in a stereospecific fashion, transferring D2R selectivity toward D3R via inversion of the stereochemistry around these cyclic aliphatic linkers [e.g., (-)-(1S,2R)-43 and (+)-(1R,2S)-42]. Pharmacological observations were supported with extensive molecular docking studies. Thus, not only is it an innovative approach to modulate the pharmacology of dopaminergic ligands described, but a new class of optically active cyclic linkers are also introduced, which can be used to expand the bitopic drug design approach toward other GPCRs.
- Battiti, Francisco O.,Bonifazi, Alessandro,Katritch, Vsevolod,Newman, Amy Hauck,Zaidi, Saheem A.
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supporting information
p. 16088 - 16105
(2021/11/16)
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- Normal Alpha Olefin Synthesis Using Dehydroformylation or Dehydroxymethylation
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The present invention discloses processes for producing normal alpha olefins, such as 1-hexene, 1-octene, 1-decene, and 1-dodecene in a multistep synthesis scheme from another normal alpha olefin. Also disclosed are reactions for converting aldehydes, primary alcohols, and terminal vicinal diols into normal alpha olefins.
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Paragraph 0127; 0128; 0129
(2019/09/06)
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- Oxidative Dehydroxymethylation of Alcohols to Produce Olefins
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Catalyst compositions for the conversion of aldehyde compounds and primary alcohol compounds to olefins are disclosed herein. Reactions include oxidative dehydroxymethylation processes and oxidative dehydroformylation methods, which are beneficially conducted in the presence of a sacrificial acceptor of H2 gas, such as N,N-dimethylacrylamide.
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Paragraph 0057; 0058
(2019/09/06)
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- Site-Selective Mono-Oxidation of 1,2-Bis(boronates)
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Site-selective oxidation of vicinal bis(boronates) is accomplished through the use of trimethylamine N-oxide in 1-butanol solvent. The reaction occurs with good efficiency and selectivity across a range of substrates, providing 2-hydro-1-boronic esters which are shown to be versatile intermediates in the synthesis of chiral building blocks.
- Yan, Lu,Morken, James P.
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supporting information
p. 3760 - 3763
(2019/05/24)
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- Versatile etherification of alcohols with allyl alcohol by a titanium oxide-supported molybdenum oxide catalyst: Gradual generation from titanium oxide and molybdenum oxide
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Etherification using allyl alcohol to produce allyl ether via dehydration is a fundamental technique for producing fine chemicals that can be applied to electronic devices. We demonstrate a sustainable method to synthesize allyl ethers from allyl alcohol with various alcohols up to a 91% yield, with water as the sole by-product. In this reaction, the active catalyst is gradually generated as the reaction proceeds through the simple mixing of TiO2 and MoO3. The dispersion of MoO3 on the spent catalyst has been observed by XRD, HAADF-STEM, and STEM-EDS mapping. This catalyst shows excellent catalytic activity by virtue of the highly dispersed nature of MoO3 supported on TiO2, which is reusable at least five times. According to a mechanistic study including the measurement of XPS of MoO3 on TiO2 and control experiments using SiO2 and Al2O3 supports, the suitable reducibility of MoO3 to coordinate the allyl moiety on TiO2 seems to be a key factor for high-yielding syntheses of various allyl ethers even under heterogeneous reaction conditions. The reaction mechanism is considered to be as follows: σ-allyl species are formed from dehydration of the allyl alcohol, followed by a nucleophilic attack by another alcohol against the σ-allyl carbon to give allyl ethers. The developed catalytic system should be suitable for easily handled syntheses of allyl ethers due to the employment of commercially available MoO3 and TiO2 with halide- and organic solvent-free reaction conditions.
- Kon, Yoshihiro,Fujitani, Tadahiro,Nakashima, Takuya,Murayama, Toru,Ueda, Wataru
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p. 4618 - 4625
(2018/09/29)
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- Nano-dispersed platinum(0) in organically modified silicate matrices as sustainable catalysts for a regioselective hydrosilylation of alkenes and alkynes
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Nano-dispersed platinum(0) particles stabilized in a range of organically modified silicate (ORMOSIL) matrices are investigated as sustainable catalysts for the hydrosilylation of alkenes and alkynes. In this study, five different siloxane matrices including triethoxysilane (HTEOS), methyltriethoxysilane (MTES), ethyltriethoxysilane (ETES), triethoxyvinylsilane (TEVS) and propyltriethoxysilane (PTES) are investigated, and the distribution of the metal particles in these materials analyzed by transition electron microscopy (TEM). The particles appeared to be generally of a small size, with a diameter of ca. 2-5 nm in each of these catalysts, however the distribution is not equally uniform from one matrix to the other. HTEOS, MTES and ETES that respectively carry a hydrogen, a methyl and an ethyl group on the triethoxysilane moiety, displayed a more uniform distribution, while particles appeared to be more scattered in the remaining matrices. Catalysts with a uniform particles distribution produced higher and consistent yields, while those with poor particles distribution produced lower and almost random yields, suggesting that the uniformity in particle distribution, and by extension the nature of the siloxane matrix, are important for the catalytic properties of these materials. The scope of the reaction was broadened to a range of olefins, with a goal of investigating the tolerability of the reaction toward a number of reactive functional groups, resulting in the preparation of 28 compounds. This catalytic system also enabled the hydrosilylation of a limited number of alkynes under the optimized reaction conditions.
- Duke, Brett J.,Akeroyd, Evan N.,Bhatt, Shreeja V.,Onyeagusi, Chibueze I.,Bhatt, Shreya V.,Adolph, Brandy R.,Fotie, Jean
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p. 11782 - 11795
(2018/07/25)
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- Tandem Catalysis: Transforming Alcohols to Alkenes by Oxidative Dehydroxymethylation
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We report a Rh-catalyst for accessing olefins from primary alcohols by a C-C bond cleavage that results in dehomologation. This functional group interconversion proceeds by an oxidation-dehydroformylation enabled by N,N-dimethylacrylamide as a sacrificial acceptor of hydrogen gas. Alcohols with diverse functionality and structure undergo oxidative dehydroxymethylation to access the corresponding olefins. Our catalyst protocol enables a two-step semisynthesis of (+)-yohimbenone and dehomologation of feedstock olefins.
- Wu, Xuesong,Cruz, Faben A.,Lu, Alexander,Dong, Vy M.
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p. 10126 - 10130
(2018/08/23)
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- Auto-Tandem Catalysis with Frustrated Lewis Pairs for Reductive Etherification of Aldehydes and Ketones
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Herein we report that a single frustrated Lewis pair (FLP) catalyst can promote the reductive etherification of aldehydes and ketones. The reaction does not require an exogenous acid catalyst, but the combined action of FLP on H2, R-OH or H2O generates the required Br?nsted acid in a reversible, “turn on” manner. The method is not only a complementary metal-free reductive etherification, but also a niche procedure for ethers that would be either synthetically inconvenient or even intractable to access by alternative synthetic protocols.
- Bakos, Mária,Gy?m?re, ádám,Domján, Attila,Soós, Tibor
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supporting information
p. 5217 - 5221
(2017/04/27)
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- Template-Assisted meta-C?H Alkylation and Alkenylation of Arenes
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To expand the scope of meta-functionalization, a pyrimidine-based template effective for the formation of β-aryl aldehydes and ketones, using allyl alcohols, by meta-C?H activation of benzylsulfonyl esters is described. In addition, α,β-unsaturated aldehydes were generated by in situ olefination and deprotection of allyl benzyl ethers. These new functionalizations at the meta-position of an arene have also been successfully implemented in benzylphosphonate, phenethyl carbonyl, and phenethylsulfonyl ester scaffolds. Key to these successful new functionalizations is the creation of an electropositive palladium center by accepting the electron cloud from the metal to the energetically low-lying π-orbitals of pyrimidine ring, and it favors coordination of allyl alcohol to the metal center.
- Bag, Sukdev,Jayarajan, Ramasamy,Mondal, Rahul,Maiti, Debabrata
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supporting information
p. 3182 - 3186
(2017/03/17)
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- Copper-catalyzed intermolecular chloro- and bromotrifluoromethylation of alkenes
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A highly practical copper-catalyzed intermolecular halotrifluoromethylation of alkenes has been developed under mild reaction conditions. A variety of Cl/Br-containing trifluoromethyl derivatives were directly synthesized from a wide range of alkenes, including electron-deficient and unactivated alkenes.
- Fu, Mingyang,Chen, Long,Jiang, Yongpeng,Jiang, Zhong-Xing,Yang, Zhigang
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supporting information
p. 348 - 351
(2016/02/19)
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- Synthesis of ethers from carbonyl compounds by reductive etherification catalyzed by iron(III) and silyl chloride
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A simple iron- and silyl chloride catalyzed method for the preparation of symmetrical and nonsymmetrical ethers is presented. Various aldehydes and ketones were reductively etherified by using triethylsilane as a reducing agent in the presence of 2 mol% of iron(III) oxo acetate and 8 mol% of chloro(trimethyl)silane. The reactions can be carried out at ambient temperatures and pressures with ethyl acetate as the solvent.
- Savela, Risto,Leino, Reko
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p. 1749 - 1760
(2015/06/16)
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- Hydrogen-bond-activated palladium-catalyzed allylic alkylation via allylic alkyl ethers: Challenging leaving groups
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C-O bond cleavage of allylic alkyl ether was realized in a Pd-catalyzed hydrogen-bond-activated allylic alkylation using only alcohol solvents. This procedure does not require any additives and proceeds with high regioselectivity. The applicability of this transformation to a variety of functionalized allylic ether substrates was also investigated. Furthermore, this methodology can be easily extended to the asymmetric synthesis of enantiopure products (99% ee).
- Huo, Xiaohong,Quan, Mao,Yang, Guoqiang,Zhao, Xiaohu,Liu, Delong,Liu, Yangang,Zhang, Wanbin
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supporting information
p. 1570 - 1573
(2014/04/17)
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- Repairing the thiol-ene coupling reaction
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Thiol-ene coupling (TEC) reactions emerged as one of the most useful processes for coupling different molecular units under reaction mild conditions. However, TEC reactions involving weak C-H bonds (allylic and benzylic fragments) are difficult to run and often low yielding. Mechanistic studies demonstrate that hydrogen-atom transfer processes at allylic and benzylic positions are responsible for the lack of efficiency of the radical-chain process. These competing reactions cannot be prevented, but reported herein is a method to repair the chain process by running the reaction in the presence of triethylborane and catechol. Under these reaction conditions, a unique repair mechanism leads to an efficient chain reaction, which is demonstrated with a broad range of anomeric O-allyl sugar derivatives including mono-, di-, and tetrasaccharides bearing various functionalities and protecting groups. In good repair: Undesired hydrogen-atom transfers are responsible for the lack of efficiency in thiol-ene coupling reactions involving allyl glycosides. This competing reaction cannot be prevented but can be very efficiently repaired by carrying out the reaction in the presence of triethylborane and catechol.
- Povie, Guillaume,Tran, Anh-Tuan,Bonnaffe, David,Habegger, Jacqueline,Hu, Zhaoyu,Le Narvor, Christine,Renaud, Philippe
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supporting information
p. 3894 - 3898
(2014/05/06)
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- Regioselective allene hydroarylation via one-pot allene hydrosilylation/Pd-catalyzed cross-coupling
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Advances in hydroarylation have been achieved by the development of a one-pot regioselective allene hydrosilylation/Pd(0)-catalyzed cross-coupling protocol. The regioselectivity is primarily governed by N-heterocyclic carbene (NHC) ligand identity in the hydrosilylation step and is preserved in the subsequent cross-coupling reaction. This methodology affords streamlined access to functionalized 1,1-disubstituted alkenes with excellent regiocontrol. (Chemical Equation Presented).
- Miller, Zachary D.,Montgomery, John
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supporting information
p. 5486 - 5489
(2015/01/09)
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- PRECURSOR COMPOUNDS AND METHODS FOR MAKING SAME
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The present invention relates to a method of obtaining radiopharmaceutical precursors, and in particular precursors to protected amino acid derivatives, which are used as precursors for production of radiolabelled amino acids for use in in vivo imaging procedures, such as positron emission tomography (PET).
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Paragraph 00044-00049
(2013/03/26)
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- A new enantioselective approach to the core structure of hypoxia selective prodrugs related to the duocarmycins
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The indoline scaffold of hypoxia selective prodrugs of DNA-alkylating agents related to the duocarmycin natural products was synthesized via an enantioselective Friedel-Crafts alkylation. Easily accessible starting materials and good stereoselectivity in the alkylation step provide an enantioselective synthesis of the DNA-alkylating subunit.
- Heinrich, Daniel M.,Youte, Jean-Jacques,Denny, William A.,Tercel, Moana
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supporting information; experimental part
p. 7000 - 7003
(2012/02/05)
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- Stereoselective synthesis of the C31-C40/C43-C52 unit of amphidinol 3
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(Chemical Equation Presented) A concise synthesis of a tetrahydropyran ring system corresponding to the C31-C40 and C43-C52 units of amphidinol 3 is described. Successive chemoselective reactions, i.e., cross-metathesis to differentiate the iodoolefin fro
- Kanemoto, Mitsunori,Murata, Michio,Oishi, Tohru
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supporting information; experimental part
p. 8810 - 8813
(2010/03/01)
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- Development of highly chemoselective bulky zincate complex, tBu 4ZnLi2: Design, structure, and practical applications in small-/macromolecular synthesis
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We present full details of the unique reactivities of the newly developed dianion-type bulky zincate, dilithium tetra-ferf-butylzincate (tBu 4ZnLi2). With this reagent, halogen-zinc exchange reaction of variously functionalized haloaromatics and anionic polymerization of N-isopropylacrylamide (NIPAm)/styrene with excellent chemoselectivity were realized. Halogen-zinc exchange reaction followed by electrophilic trapping with propargyl bromide provided a convenient route to functionalized phenylallenes, particularly those with electrophilic functional groups (such as cyano, amide and halogens). Spectral and computational studies of the structure in the gas and liquid phases indicated extraordinary stabilization of this dianion-type zincate by its bulky ligands.
- Furayama, Taniyuki,Yonehara, Mitsuhiro,Arimoto, Sho,Kobayashi, Minoru,Matsumoto, Yotaro,Uchiyama, Masanobu
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supporting information; scheme or table
p. 10348 - 10356
(2009/10/10)
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- Allyl sulfides are privileged substrates in aqueous cross-metathesis: Application to site-selective protein modification
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Allyl sulfides undergo efficient cross-metathesis in aqueous media with Hoveyda-Grubbs second generation catalyst 1. The high reactivity of allyl sulfides in cross-metathesis was exploited in the first examples of cross-metathesis on a protein surface. S-Allylcysteine was incorporated chemically into the protein, providing the requisite allyl sulfide handle. Preliminary efforts to genetically incorporate S-allylcysteine into proteins are also reported. Copyright
- Lin, Yuya A.,Chalker, Justin M.,Floyd, Nicola,Bernardes, Goncalo J. L.,Davis, Benjamin G.
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supporting information; experimental part
p. 9642 - 9643
(2009/02/04)
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- Hexafluoroisopropanol as a unique solvent for stereoselective lododesilylation of vinylsilanes
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Stereoselective preparation of iodoalkenes from vinylsilanes is described. 1,1,1,3,3,3-Hexafluoroisopropanol serves as a unique solvent that ensures high yields and stereoselectivities in the iododesilylation of a variety of functionalized substrates.
- Ilardi, Elizabeth A.,Stivala, Craig E.,Zakarian, Armen
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supporting information; experimental part
p. 1727 - 1730
(2009/04/10)
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- Sequential C-Si bond formations from diphenylsilane: Application to silanediol peptide isostere precursors
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The report of silanediol peptide isosteres as highly active inhibitors of proteolytic enzymes has triggered an increased interest for these compounds, thereby necessitating a general and direct synthetic access to this unusual class of protease inhibitors. In this paper, we report on thetwo-step assembly of the carbon-silicon backbone of a silane-containing dipeptide fragment. The synthetic scheme is comprised of an alkene hydr osilylation step with the simple precursor, diphenylsilane, using eithera radical initiator or RhCl(PPh 3)3, Wilkinson's catalyst, for the creation of a hydridosilane and the first new carbon-s ilicon bond. The next step is the reduction of this hydridosilane with lithium metal providing a silyl lithium reagent, which undergoes a highlydiastereoselective addition to an optically active tert-butanesulfinimi ne, thus generating the second C-Si bond. This method allows sequential functionalization of the two hydrides in diphenylsilane by chemoselective discrimination.
- Nielsen, Lone,Skrydstrup, Troels
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supporting information; experimental part
p. 13145 - 13151
(2009/03/12)
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- [IrCl2Cp*(NHC)] complexes as highly versatile efficient catalysts for the cross-coupling of alcohols and amines
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A comparative study on the catalytic activity of a series of [IrCl 2Cp*(NHC)] complexes in several C-O and C-N coupling processes implying hydrogen-borrowing mechanisms has been performed. The compound [IrCl2Cp*(InBu)] (Cp* = pentamethyl cyclopentadiene; InBu = 1,3-di-n-butylimidazolylidene) showed to be highly effective in the cross-coupling reactions of amines and alcohols, providing high yields in the production of unsymmetrical ethers and N-alkylated amines. A remarkable feature is that the processes were carried out in the absence of base, phosphine, or any other external additive. A comparative study with other known catalysts, such as Shvo's catalyst, is also reported.
- Prades, Amparo,Corberan, Rosa,Poyatos, Macarena,Peris, Eduardo
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scheme or table
p. 11474 - 11479
(2009/12/03)
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- Toward a protecting-group-free halogen-metal exchange reaction: Practical, chemoselective metalation of functionalized aromatic halides using dianion-type zincate,tBu4ZnLi2
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A versatile preparation method for aromatic zincate compounds through a halogen-zinc exchange reaction using dilithium tetra-tert-butylzincate (tBu4ZnLi2) has been developed. This reagent permits efficient preparation of highly functionalized aromatic zincates, particularly, those with electrophilic functional groups, such as ester, amide, alcohol, and phenol. Halogen-zinc exchange reactions followed by electrophilic trapping (with allyl bromide or benzaldehyde) proved to be a powerful tool for C-C bond formation on functionalized aromatic rings. The functionalized aromatic zincate intermediate was also found to undergo copper- and palladium-catalyzed C-C bond-forming reactions with good yields and high chemoselectivity. Copyright
- Uchiyama, Masanobu,Furuyama, Taniyuki,Kobayashi, Minoru,Matsumoto, Yotaro,Tanaka, Kentaro
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p. 8404 - 8405
(2007/10/03)
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- Studies on the synthesis of Richardianidin-1 via the tautomer-arrested annulation of Fischer carbene complexes
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A strategy for the synthesis of richardianidin-1 is evaluated which has as its key step the tautomer-arrested annulation of chromium-carbene complexes. Both inter- and intramolecular variations of the strategy are examined. The intramolecular reaction involves the tethering of the alkyne to the oxygen stabilizing substituent of the carbene carbon. The outcome of the intramolecular tautomer-arrested annulation was found to be highly dependent on the nature of the tether and the on the type of substituent on the alkyne. The product distribution from these reactions included the desired hydrindenone resulting from tautomer-arrested annulation, a naphthalenedione, and a spirocyclohexadienone. The latter two products result from CO insertion prior to cyclization. The optimal tether length for the tautomer-arrested product is four atoms between the alkyne and the carbene carbon. The yields for the intramolecular reaction dropped significantly for a substituent on the alkyne terminus that was larger than a methyl group and this was not suitable for a synthesis of richardianidin-1. Initial studies on the intermolecular tautomer-arrested annulation focused on the regioselectivity of alkyne incorporation. The reaction with isopropyl(methyl)acetylene gives a single regioisomer and reveals that the tautomer-arrested annulation is more regioselective than the normal benzannulation. Furthermore, the intermolecular reaction is more tolerant of larger substituents on the terminus of the alkyne. As a result of the studies on the intermolecular tautomer-arrested annulation a suitable alkyne was found that introduces all of the carbons present in the six-membered lactone of richardianidin-1. Georg Thieme Verlag Stuttgart.
- Bos, Mary Ellen,Loncaric, Catherine,Wu, Chunrui,Wulff, William D.
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p. 3679 - 3705
(2008/03/14)
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- A MULTICORE CHEMICAL COMPOUND LIBRARY
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There is provided a method to convert O-functionalized indazolinone-derivatives to the corresponding N2-functinoalised indazolinone derivatives, by use of microwave energy or a transition metal catalyst. A preferred catalyst is palladium tetrakis. The method described allows the creation of a library of chemical compounds which can be screened for biological activity.
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Page/Page column 27-35
(2010/02/15)
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- Catalytic asymmetric Claisen rearrangement in natural product synthesis: Synthetic studies toward (-)-xeniolide F
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(Chemical Equation Presented) The catalytic asymmetric Claisen rearrangement (CAC) of a highly substituted and functionalized α-alkoxycarbonyl-substituted allyl vinyl ether has been exploited to gain access to an advanced building block for the projected total synthesis of (-)-xeniolide F, the enantiomer of a xenicane diterpene isolated from a coral of the genus Xenia.
- Pollex, Annett,Hiersemann, Martin
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p. 5705 - 5708
(2007/10/03)
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- Halide-Free Dehydrative Allylation Using Allylic Alcohols Promoted by a Palladium-Triphenyl Phosphite Catalyst
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The triphenyl phosphite-palladium complex was found to effect catalytic substitution reactions of allylic alcohols via a direct C-O bond cleavage. The dehydrative etherification proceeded efficiently without any cocatalysts and bases to give allylic ethers in good to excellent yields.
- Kayaki, Yoshihito,Koda, Takashi,Ikariya, Takao
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p. 2595 - 2597
(2007/10/03)
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- Allylation of Alcohols and Carboxylic Acids with Allyl Acetate Catalyzed by [Ir(cod)2]+BF4- Complex
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A facile method for the synthesis of allyl alkyl ethers from alcohols with allyl acetate was developed by the use of [Ir(cod)2] +BF4- complex. For instance, the reaction of allyl acetate with n-octyl alcohol in the presence of a catalytic amount of [Ir(cod)2]+BF4- complex afforded allyl octyl ether in quantitative yield. Allyl carboxylates were also prepared by the exchange reaction between carboxylic acids and allyl acetate in good yields. The [Ir(cod)2]+BF4- complex catalyzed the reaction of alkyl and aromatic amines with allyl acetate to lead to the corresponding allylamines in fair to good yields.
- Nakagawa, Hideto,Hirabayashi, Tomotaka,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 3474 - 3477
(2007/10/03)
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- Process for producing allyl-containing compounds
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An allyl-containing compound represented by following Formula (3): wherein R2, R3, R4, R5 and R6 may be the same as or different from one another and each represent hydrogen atom or an organic group; R7 represents an organic group; and Y represents oxygen atom or sulfur atom, is produced by reacting an allyl ester compound represented by following Formula (1): wherein R1 represents hydrogen atom or an organic group; and R2, R3, R4, R5 and R6 are as defined above, with a compound represented by following Formula (2):R7-Y-H wherein R7 is an organic group; and Y is as defined above, in the presence of at least one transition element compound.
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- Solid-supported cyclohexane-1,3-dione (CHD): A "capture and release" reagent for the synthesis of amides and novel scavenger resin
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A three-step synthesis of cyclohexane-1,3-dione (CHD) resin 6 on polystyrene resin is described. Resin 6 was used to prepare an amide library of high purity by microwave-assisted serial "capture and release" and can be recycled for this purpose. High-loading CHD resin 10 was also shown to scavenge allyl cations in solution.
- Humphrey, Cara E.,Easson, Morag A. M.,Tierney, Jason P.,Turner, Nicholas J.
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p. 849 - 852
(2007/10/03)
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- Tandem hydroformylation/Fischer indole synthesis: A novel and convenient approach to indoles from olefins
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(Matrix presented) A novel one-pot synthesis of indole systems via tandem hydroformylation/Fischer indole synthesis starting from olefins and arylhydrazines is described. This tandem procedure leads directly to 3-substituted indoles if unsubstituted phenylhydrazine is used and to 3,5- respectively 3,7-disubstituted indoles if para- or ortho-substituted arylhydrazines are used.
- Koehling, Petra,Schmidt, Axel M.,Eilbracht, Peter
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p. 3213 - 3216
(2007/10/03)
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- SmI2/water/amine mediates cleavage of allyl ether protected alcohols: application in carbohydrate synthesis and mechanistic considerations.
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[reaction: see text]. SmI2/H2O/amine provides selective cleavage of unsubstituted allyl ethers in good to excellent yields. This method is therefore useful in deprotection of alcohols and carbohydrates.
- Dahlen, Anders,Sundgren, Andreas,Lahmann, Martina,Oscarson, Stefan,Hilmersson, Goeran
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p. 4085 - 4088
(2007/10/03)
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- Oxidation of Unsaturated Ethers with the System Aluminum Tri-tert-butylate-tert-Butyl Hydroperoxide
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The system aluminum tri-tert-butylate-tert-butyl hydroperoxide oxidizes alkyl allyl and aryl allyl ethers by the radical mechanism at room temperature. In the process, either the substrate skeleton is preserved and the carbonyl and hydroperoxy groups are introduced, or the carbon-carbon and carbon-oxygen bonds in the allyl moiety are cleaved. In allyl benzyl ether the reaction centers are the methylene groups of the benzyl and allyl fragments.
- Stepovik, L. P.,Martynova, I. M.,Dodonov, V. A.
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p. 1802 - 1806
(2007/10/03)
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- Novel reactions of ethylene acetals with silyl-substituted nucleophiles. A mild and efficient procedure for the synthesis of homoallyl alkyl ethers and unsymmetrical dialkyl ethers
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Efficient one-pot synthesis of homoallyl alkyl ethers and dialkyl ethers was performed by the allylation and reduction of ethylene acetals with allyltrimethylsilane and t-butyldimethylsilane, respectively, in the presence of alkoxytrimethylsilane.
- Suzuki, Takeshi,Oriyama, Takeshi
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p. 1263 - 1269
(2007/10/03)
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- Selectivity in the tandem cyclization - Carboxylation reaction of unsaturated haloaryl ethers catalyzed by electrogenerated nickel complexes
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The electrochemical reduction of a series of 2-haloaryl ethers containing allyl and propargyl groups under CO2 allows the synthesis of benzofuranacetic acid derivatives. This novel intramolecular cyclization- carboxylation reaction is carried out in single-compartment cells and is catalyzed by [Ni(cyclam)Br2].
- Olivero,Du?ach
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p. 1885 - 1891
(2007/10/03)
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- Pentacoordinate organoaluminum chemistry: Catalytic efficiency of Me3Al in the epoxide cleavage with alkynyllithiums
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A new and highly effective catalytic method for epoxide alkynylations has been developed that involves the chelation-controlled alkylation of heterosubstituted epoxides with Me3Al via pentacoordinate organoaluminum complexes by taking advantage of the exceedingly high affinity of aluminum to oxygen. For example, reaction of epoxy ether, (1-benzyloxy)-3-butene oxide (1), in toluene with PhC?CLi under the influence of catalytic Me3Al (10 mol%) proceeded smoothly at 0 °C for 5 h to furnish the alkynylation product, 1-(benzyloxy)-6-phenylhex-5-yn-3-ol, in 76% yield [cf. 3% without Me3Al catalyst; 78% with stoichiometric Me3Al under similar conditions]. This represents the first catalytic procedure for the amphiphilic alkylation of epoxides. The participation of pentacoordinate Me3Al complexes of epoxy ethers of type 1 is emphasized by comparing the reactivity with the corresponding simple epoxide, 5-phenyl-1-pentene oxide, which was not susceptible to nucleophile attack of PhC?CLi with catalytic Me3Al under similar conditions. The pentacoordinate complex formation of Me3Al with epoxy ether 1 is characterized by low-temperature 13C and 27Al NMR spectroscopy. This approach is also applicable to the selective alkynylation of tosyl aziridines with adjacent ether functionality, which provides a promising method for amino alcohol synthesis.
- Ooi,Kagoshima,Ichikawa,Maruoka
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p. 3328 - 3333
(2007/10/03)
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- Synthesis and fluoride-promoted Wittig rearrangements of α-alkoxysilanes
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(matrix presented) Lewis acid-catalyzed reaction of allyl and benzyl trichloroacetimidates with α-silyl alcohols was found to be a general method for the synthesis of α-alkoxysilanes. Upon exposure to CsF, these α-alkoxysilanes could be made to undergo [2,3]-Wittig rearrangement with an efficiency similar to that realized by the analogous but inherently more toxic α-alkoxystannanes.
- Maleczka Jr., Robert E.,Geng, Feng
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p. 1111 - 1113
(2008/02/09)
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- Auxiliary accelerated reactions: Towards the use of catalytic chiral auxiliaries
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In competition experiments, the acceleration of reactivity of alkenes tethered to pyridyl groups compared with the corresponding alkenes tethered to phenyl groups in the presence of transition metals was demonstrated for two reaction types: Diels-Alder cycloaddition of enoate esters and catalytic hydrogenation of allylic and homoallylic ethers. The rate accelerations observed are of crucial importance in the development of a new concept for asymmetric catalysis: chiral auxiliaries which can function in a catalytic manner.
- Westwell, Andrew D.,Williams, Jonathan M. J.
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p. 13063 - 13078
(2007/10/03)
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- Total Synthesis of Swinholide A, Preswinholide A, and Hemiswinholide A
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The total synthesis of swinholide A (1) has been accomplished via key intermediate aldehyde 12 (Fig. 3), whose construction started from L-rhamnose (18), epoxide 21, and phenylsulfone orthoester 22, and proceeded through an Enders asymmetric alkylation (16 + 17 -> 15), a Ghosez cyclization (21 + 22 -> 20), and a Corey-Sharpless coupling reaction (13 + 14 -> 12).Elaboration of compound 12 along slightly different pathways culminated in the synthesis of carboxylic acid 10 and hydroxy compound 11, whose union by an esterification reaction, followed by ring closure of the subsequently derived hydroxy acid under Yamaguchi conditions, led to swinholide A (1) upon deprotection.The chemistry developed also allowed the total synthesis of preswinholide A methyl ester (7), preswinholide A (8), and hemiswinholide A (78).Keywords: natural products; swinholide A; total syntheses
- Nicolaou, K. C.,Patron, A. P.,Ajito, K.,Richter, P. K.,Khatuya, H.,et al.
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p. 847 - 868
(2007/10/03)
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- Synthesis of 9--adenine and -guanine
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2,2-Dichloro-3-(benzyloxymethyl)cyclobutanone 15, which was prepared in 50percent yield by the cycloaddition of dichloroketene to allyl benzyl ether 14, was converted in four steps and in ca. 40percent overall yield into trans-3-(benzyloxymethyl)cyclobutanol 11b.The latter alcohol 11b was coupled under Mitsunobu conditions with 6-(4-chlorophenylsulfanyl)-9H-purine 21b and 6-(4-chlorophenylsulfanyl)-2-(phenylacetamido)-9H-purine 21c to give the 9-cyclobutylpurine derivatives 22 and 24, respectively, in 88 and 60percent yield.The former product 22 was converted in three steps and in 39percent overall yield into 9-adenine 6, and the latter product was converted in four steps and in 42percent overall yield into 9-guanine 7.X-Ray crystallographic data relating to compounds 22 and 24 are also reported.
- Kaiwar, Vijay,Reese, Colin B.,Gray, Emily J.,Neidle, Stephen
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p. 2281 - 2288
(2007/10/02)
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- REACTIONS OF PHOSPHORUS PENTACHLORIDE WITH ALLYL ARYL ETHERS, SULFIDES, AND NAPHTHALENE DERIVATIVES
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Conditions for phosphorylation of allyl aryl and aryl methylallyl ethers and sulfides, as well as alkenyl- and alkoxynaphthalenes, have been developed.
- Anisimova, E. A.,Mitrasov, Yu. N.,Kormachev, V. V.
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p. 356 - 360
(2007/10/03)
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- Efficient reductive etherification of carbonyl compounds with alkoxytrimethylsilanes
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An efficient TMSOTf catalyzed ether synthesis from carbonyl compounds and alkoxytrimethylsilanes via triethylsilane-reduction is described.
- Hatakeyama, Susumi,Mori, Hisato,Kitano, Kaori,Yamada, Hidetoshi,Nishizawa, Mugio
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p. 4367 - 4370
(2007/10/02)
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- Carbon-functionalized 1,4 7-Trithiacyclononanes: Synthesis, Molecular Mechanics and Co-ordination Chemistry
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A series of functionalized analogues of 1,4,7-trithiacyclononane has been synthesized and the effects of functionalization on their co-ordination chemistry investigated.The substituents were introduced via substituted 1,2-dibromopropanes, by cyclization with 3-thiapentane-1,5-dithiolate in the form of its molybdenum complex (2-).The functionalized macrocycles were then displaced from the metal by additional 3-thiapentane-1,5-dithiolate.A series of complexes (n+) (M = Ag, Hg, Cu, Ni, Co or Fe; L = 2-methyl-1,4,7-trithiacyclononane, the simplest of the new ligands) was prepared.Spectroscopic and electrochemical studies revealed that any effects of substitution on the ring conformational preferences were not manifested in the stability or electrochemistry of the complexes.Molecular-mechanics calculations suggest that no alterations in conformational preferences are caused by a single substitution.Attempts to synthesize analogues with two vicinal methyl groups yielded only polymeric products.
- Smith, Raymond J.,Salek, Spencer N.,Went, Michael J.,Blower, Philip J.,Barnard, Neil J.
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p. 3165 - 3170
(2007/10/02)
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- Stereoselective construction of the C18-C32 fragment of swinholide A
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A stereoselective construction of the fully functionalized C18-C32 fragment 3 of swinholide A 1 starting with building blocks 4 and 5 is described.
- Richter,Tomaszewski,Miller,Patron,Nicolaou
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p. 1151 - 1152
(2007/10/02)
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