- Divergent and Multi-Stage Photoisomerization of Four-Coordinated Boron Compounds with a Naphthyl-Pyridyl/Thiazolyl Backbone
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Examination of the photoreactivity of a new class of N,C-chelate organoboron compounds, including a series of unsymmetrically substituted boron molecules, B(naph-pyridyl)(Ar1)(Ar2) and B(naph-thiazolyl)(Ar1)(Ar2
- He, Zhechang,Liu, Lijie,Zhao, Zhenhui,Mellerup, Soren. K.,Ge, Yuxin,Wang, Xiang,Wang, Nan,Wang, Suning
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Read Online
- METHOD FOR SYNTHESIZING BORONATE ESTER COMPOUND, SODIUM SALT OF BORONATE ESTER COMPOUND, AND METHOD FOR SYNTHESIZING THE SAME
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An object is to establish a technology with which a boronate ester compound can be easily and efficiently synthesized at a low cost with a small number of steps without the need for a complex chemical method and reagents that need to be carefully handled. A further object is to establish a sodium salt of a boronate ester compound that is a novel compound and a technology for synthesizing the sodium salt of a boronate ester compound. Provided are a sodium salt of a boronate ester compound and a method for synthesizing a boronate ester compound or a sodium salt of a boronate ester compound that includes reacting, in a reaction solvent, an organic chloride with a dispersion product obtained by dispersing sodium in a dispersion solvent to obtain an organic sodium compound, and reacting the obtained organic sodium compound with a borate ester compound to obtain a boronate ester compound or a sodium salt of a boronate ester compound.
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Paragraph 0126
(2021/03/13)
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- Borylation using group IV metallocene under mild conditions
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A borylation reaction of aromatic diazonium salts has been optimized using titanocene and zirconocene derivatives as catalysts. The reaction employs diisopropylaminoborane as a borylating agent and proceeds smoothly at room temperature to provide arylboronates after methanolysis and transesterification with pinacol. The reaction mechanism has been found to proceed via a radical pathway.
- Marciasini, Ludovic D.,Vaultier, Michel,Pucheault, Mathieu
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p. 1702 - 1705
(2014/03/21)
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- Mn-catalyzed aromatic C-H alkenylation with terminal alkynes
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The first manganese-catalyzed aromatic C-H alkenylation with terminal alkynes is described. The procedure features an operationally simple catalyst system containing commercially available MnBr(CO)5 and dicyclohexylamine (Cy2NH). The reaction occurs readily in a highly chemo-, regio-, and stereoselective manner delivering anti-Markovnikov E-configured olefins in high yields. Experimental study and DFT calculations reveal that (1) the reaction is initiated by a C-H activation step via the cooperation of manganese and base; (2) manganacycle and alkynylmanganese species are the key reaction intermediates; and (3) the ligand-to-ligand H-transfer and alkynyl-assisted C-H activation are the key steps rendering the reaction catalytic in manganese.
- Zhou, Bingwei,Chen, Hui,Wang, Congyang
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supporting information
p. 1264 - 1267
(2013/03/14)
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- Synthesis of phenylboronic acids in continuous flow by means of a multijet oscillating disc reactor system operating at cryogenic temperatures
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A multijet oscillating disk (MJOD) millireactor system suitable for operating at cryogenic temperatures has been developed, assembled, and investigated. This new reactor system (cryoMJOD) was realized with the purpose to prepare various phenylboronic acids in a continuous two (three)-step telescoped synthetic process at temperatures in the interval -50 to -75 °C. In this process, n-butyllithium was reacted with a phenylbromide to provide the corresponding phenyllithium derivative, whereupon a borate was added under the formation of target product phenylboronic acid in good selectivity and medium-to-good yield (50-75%). These results were competitive with results previously revealed in the literature. The residence times of the telescoped two-step process were considerably shorter compared to those of batch mode operations for the identical syntheses. The flow process was optimized by means of statistical experimental design and multivariate regression, upon which the process was utilized for the production of a series of phenylboronic acid derivatives, all in medium-to-good yield. One of the substrates, 4-methoxyphenylboronic acid, was submitted for throughput improvements, resulting in a process with capability to produce the product phenylboronic acid in a quantity of 2.0 kg × day-1.
- Sleveland, Dagfinn,Bjorsvik, Hans-Rene
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experimental part
p. 1121 - 1130
(2012/08/27)
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- Enantioselective synthesis of cis-1,2-disubstituted cyclopentanes and cyclohexanes by Suzuki-Miyaura cross-coupling and iridium-catalyzed asymmetric hydrogenation
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A series of 1,2-disubstituted cyclohexene derivatives was prepared through Suzuki-Miyaura cross-coupling of 2-bromo-1-cyclohexenecarbaldehyde or 2-carbomethoxy-1-cyclohexen-1-yl triflate with arylboronates. These tetra-substituted cyclic alkenes were subjected to Ir-catalyzed asymmetric hydrogenation. In this way cis-1-methoxymethyl-2-arylcyclohexanes were obtained in high yield with excellent enantio- and diastereoselectivities (up to >99%ee, >99%cis) by using phosphinomethyloxazolines as ligands. Asymmetric hydrogenation of analogous cyclopentene derivatives, prepared by Suzuki-Miyaura cross-coupling, proved to be more difficult and proceeded with lower enantioselectivities of up to 88%ee. The synthetic potential of this cross-coupling/asymmetric-hydrogenation strategy was demonstrated by an enantioselective route to chiral hexahydrofluorenones. Alkene interest: Starting from arylboronates, a variety of cyclic, tetra-substituted olefins was prepared by Suzuki-Miyaura cross-coupling (see scheme). Subsequent Ir-catalyzed asymmetric hydrogenation with phosphanylmethyloxazoline ligand complexes led to cis-disubstituted cycloalkane derivatives in high yield and excellent enantio- and distereoselectivities. Copyright
- Schumacher, Andreas,Schrems, Marcus G.,Pfaltz, Andreas
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supporting information; experimental part
p. 13502 - 13509
(2012/01/05)
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- Reactions of CF3-substituted boranes with α-diazocarbonyl compounds
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Boranes substituted with a CF3-group can be generated from methyl boronic esters RB(OMe)2 and Me3SiCF3/KF followed by treatment with Me3SiCl. These boranes are stable only in coordinating solvents, and due to the increased Lewis acidity of boron, react rapidly with α-diazocarbonyl compounds to give the products of transfer of the organic group from boron. Alkyl, aryl, vinyl, and alkynyl boronic esters can be used in this reaction.
- Elkin, Pavel K.,Levin, Vitalij V.,Dilman, Alexander D.,Struchkova, Marina I.,Belyakov, Pavel A.,Arkhipov, Dmitry E.,Korlyukov, Alexander A.,Tartakovsky, Vladimir A.
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experimental part
p. 5259 - 5263
(2011/10/31)
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- Ortho-magnesiation of boron-substituted benzenes by using (TMP) 2Mg
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Magnesiation ortho to boron: Borylbenzenes with an N-methyl-1,3- ethylenediamino group on the boron atom undergo ortho-magnesiation upon exposure to 2,2,6,6-tetramethylpiperidide (TMP)2Mg, and the resulting ortho-magnesiated borylbenzenes can be trapped with electrophiles (see scheme).
- Kawachi, Atsushi,Nagae, Saori,Onoue, Yasuhiro,Harada, Osamu,Yamamoto, Yohsuke
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p. 8005 - 8008
(2011/09/14)
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- Functionalization of (2S)-Isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4- ones by a Suzuki-Miyaura Cross-Coupling Reaction Using Aryltrifluoroborate Salts: Convenient Enantioselective Preparation of α-Substituted β-Amino Acids
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A simple protocol for the Pd(OAc)2-catalyzed cross-coupling reaction of 1-benzoyl-(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones with potassium aryltrifluoroborates was developed. The reaction is performed at 110°C with a ligand-free catalyst. In all cases, complete conversion of the 1-benzoyl-(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-onesand aryltrifluoroborates into the C-C coupling products was observed within 30-360 min. It is noteworthy that a largevariety of groups present in the potassium aryltrifluoroborates (-CF3, -OMe, -SEt, -CN, -CHO, -Cl, -Cbz, -NCbz,-OH, -CO2H) could be tolerated. Hydrogenation of the endocyclic double bonds in the Suzuki-Miyaura products followed by acid hydrolysis afforded highly enantioenrichedα-aryl-substituted β-amino acids. We present a general approach for the synthesis of (2S)-isopropyl-5-aryl-2,3- dihydro-4(H)-pyrimidin-4-ones by Suzuki-Miyaura reaction of aryltrifluoroborate salts with(2S)-isopropyl-5-iodo-2,3-dihydro-4(H)-pyrimidin-4-ones in the presence of a palladium catalyst and a base. The arylated compounds were transformed into enantioenriched α-aryl-substituted β-amino acids. Copyright
- Stefani, Helio A.,Amaral, Monica F. Z. J.,Reyes-Rangel, Gloria,Vargas-Caporali, Jorge,Juaristi, Eusebio
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experimental part
p. 6393 - 6403
(2011/02/21)
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- Unusual dimerization of N-protected bromomethylindoles/benzyl bromide with arylmetal halides: generation of indolylmethyl/benzyl radical
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A detailed study on the interaction of N-protected bromomethylindoles with various types of aryl/alkyl Grignard is reported. Full experimental details on the mechanism of the unusual dimerization reaction are presented.
- Ramesh, Neelamegam,Prakash, Chandran,Sureshbabu, Radhakrishnan,Dhayalan, Vasudevan,Mohanakrishnan, Arasambattu K.
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p. 2071 - 2079
(2008/09/17)
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- New phenyl-substituted PPV derivatives for polymer light-emitting diodes-synthesis, characterization and structure-property relationship study
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Three new PPV derivatives with dialkoxyphenyl substituents, BEH2P-PPV, BEH3P-PPV, and BEH4P-PPV have been synthesized. The polymers were characterized by FT-IR, 1H NMR, and elemental analysis. The polymers possess excellent solubility, high molecular weights, high photoluminescence efficiencies and good thermal stability. The influence of substitution pattern on the formation of structural defects has been investigated by measuring the signal due to tolane-bisbenzyl moieties (TBB) in the proton NMR spectra. BEH2P-PPV with a steric phenyl group at the ortho-position on the side phenyl ring shows the lowest amount of TBB, which indicates suitable steric hindrance can be applied to suppress the formation of irregular head-to-head and tail-to-tail linkage in the polymer chains. In addition, the polarity of solvents used for the Gilch polymerization will also affect the amount of irregular structure in the polymers. Polar solvents such as THF will result in polymers with low TBB content. Energy level measurement from cyclic voltammetry revealed that the influences of the substitution pattern on the HOMOs and LUMOs are different. The three polymers possess similar HOMO energy levels while the LUMO of BEH4P-PPV is much higher than that of the other two polymers. Polymer light-emitting diodes fabricated from BEH2P-PPV, BEH3P-PPV, and BEH4P-PPV with the configuration of ITO/PEDOT/polymer/Ba/Al, emitted bright blue-green to green light with the maximum peaks at 496, 488, and 525 nm, respectively. The turn-on electric field and maximum external quantum efficiencies of the diodes are 0.30, 0.50, and 0.42 MV/cm and 0.37%, 0.66%, and 0.25% respectively. The quantum efficiency is mainly determined by the electron injection from the cathode. With the highest luminance, lowest turn-on electric field, and good quantum efficiency as well as negligible structural defects, BEH2P-PPV is the most promising material among the three polymers for polymer light-emitting diodes.
- Chen, Zhi-Kuan,Lee, Nancy Hoi Sim,Huang, Wei,Xu, Yi-She,Cao, Yong
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p. 1009 - 1020
(2007/10/03)
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- Substituted 3-amino biaryl propionic acids as potent VLA-4 antagonists.
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A series of substituted N-(3,5-dichlorobenzenesulfonyl)-(L)-prolyl- and (L)-azetidyl-beta-biaryl beta-alanine derivatives was prepared as selective and potent VLA-4 antagonists. The 2,6-dioxygenated biaryl substitution pattern is important for optimizing potency. Oral bioavailability was variable and may be a result of binding to circulating plasma proteins.
- Kopka, Ihor E,Lin, Linus S,Mumford, Richard A,Lanza Jr., Thomas,Magriotis, Plato A,Young, David,DeLaszlo, Stephen E,MacCoss, Malcolm,Mills, Sander G,Van Riper, Gail,McCauley, Ermengilda,Lyons, Kathryn,Vincent, Stella,Egger, Linda A,Kidambi, Usha,Stearns, Ralph,Colletti, Adria,Teffera, Yohannes,Tong, Sharon,Owens, Karen,Levorse, Dorothy,Schmidt, John A,Hagmann, William K
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p. 2415 - 2418
(2007/10/03)
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- Syntheses, structures, and coordination of diborylbipyridines and bipyridinediborates
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6,6'-Bis(diethylboryl)-2,2'-bipyridine (1a) was obtained in low yield by in situ deprotonation of 2,2'-bipyridine in the presence of diethyl(methoxy)borane. 6,6'-Dilithio-2,2'-bipyridine reacts with various alkoxyboranes leading to bipyridinediborates 2 in good yields. The derivatives 2b and 2c allow the formation of the free diborylbipyridines 1b and 1c. The coordination properties of the diboryl-bipyridines as tetra- functional donor-acceptor compounds have been used for the formation of the copper complex 4 and of the adduct 5 which is built from diborylbipyridine and a dihydroxydiboroxan derivative. The composition of the products follows from spectroscopic data and from X-ray structure analyses for 2f, 4, and 5.
- Weis, Norbert,Pritzkow, Hans,Siebert, Walter
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p. 393 - 398
(2007/10/03)
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- Synthesis of arylboronates via the palladium(0)-catalyzed cross-coupling reaction of tetra(alkoxo)diborons with aryl triflates
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The cross-coupling reaction of (RO)2BB(OR)2 (RO = methoxo and pinacolato) with aryl triflates to give arylboronates was carried out at 80°C in the presence of PdCl2(dppf) (3 mol%), dppf (3 mol%) and KOAc (3 equivs) in dioxane. The reaction was available with various functional group such as nitro, cyano, ester, and carbonyl groups.
- Ishiyama, Tatsuo,Itoh, Yoshiya,Kitano, Takahiro,Miyaura, Norio
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p. 3447 - 3450
(2007/10/03)
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