cas 16419-60-6, 2-Tolylboronic acid | Articles data

Articles about 16419-60-6Total 44 be found

Article title
Article abstract
Author
Journal number and time
Download

Deprotection of pinacolyl boronate esters via hydrolysis of intermediate potassium trifluoroborates
An efficient two-step procedure for the deprotection of pinacolyl organoboronate esters is described. Reaction with excess potassium hydrogen fluoride produces the corresponding stable, crystalline potassium organotrifluoroborate salts. Treatment of the trifluoroborates with either inorganic base or trimethylsilyl chloride and water affords the corresponding organoboronic acid in high yield.
Yuen, Alexander K.L.,Hutton, Craig A.
p. 7899 - 7903
(2005)
Read Online

Asymmetric construction of chiral C-N axes through rhodium-catalyzed 1,4-addition
Catalytic asymmetric construction of chiral C-N axes has been developed through a rhodium-catalyzed asymmetric 1,4-addition reaction. Both central chirality and axial chirality have been controlled at the same time using Rh/(R,R)-Ph-bod* catalyst with high enantio- and diastereoselectivity. This method has also been applied to the preparation of a planar-chiral ferrocene derivative. The resulting chiral C-N axis can be used as a good template to control the stereochemistry in the subsequent transformations such as alkylation and Diels-Alder reactions.
Duan, Wei-Liang,Imazaki, Yusuke,Shintani, Ryo,Hayashi, Tamio
p. 8529 - 8536
(2007)
Read Online

Aryllead triacetates in the synthesis of oxaphenanthrene derivatives
Ortho-Halomethylphenyllead triacetates (halo = bromine or chlorine) react with phenols in the presence of triethylamine and a pyridine derivative to afford modest to good yields of dibenzo[b,d]-6H-pyrans.
Fedorov, Alexey Yu,Carrara, Fabien,Finet, Jean-Pierre
p. 5875 - 5877
(2001)
Read Online

Structure, conformation, and dynamic processes of the stereolabile atropisomers of hindered terphenyl hydrocarbons
(Chemical Equation Presented) Ortho-substituted p-terphenyl hydrocarbons exist as trans and cis atropisomers that were identified by low-temperature NMR spectroscopy. The interconversion barriers increase with the dimensions of the ortho substituents, the experimental values being matched by ab initio calculations. X-ray diffraction shows that only the trans atropisomer is present in the solids. Spectra of a tert-butyl derivative in nonequilibrium conditions indicate that the cis is more populated than the trans atropisomer in solution, favored by attractive interactions.
Lunazzi, Lodovico,Mazzanti, Andrea,Minzoni, Mirko,Edgar Anderson
p. 1291 - 1294
(2005)
Read Online

Method for synthesizing sodium 2-carboxyphenylborate
The invention discloses a method for synthesizing sodium 2-carboxyphenylborate. The method comprises the following two steps of: 1) taking methyl 2-bromobenzoate as an initial raw material, through bromine removal by butyl lithium, carrying out a one-pot reaction with triisopropyl borate or trimethyl borate to obtain a product 2-methoxycarbonyl phenylboronic acid, and 2) hydrolyzing the 2-methoxycarbonyl phenylboronic acid in a sodium hydroxide methanol solution, and pulping with acetone to obtain sodium 2-carboxyphenylborate monohydrate. The method has the advantages of easily available raw materials, simple operation, safety, environmental protection, low cost and high yield.
-
Paragraph 0020-0021

(2020/06/17)

Aryl boronic acid preparation method
The invention belongs to the technical field of fine chemical engineering, and relates to an aryl boronic acid preparation method. In the prior art, aryl boronic acid as a novel safe and environmentally-friendly arylation reagent is widely used in scientific research and production of various fine chemicals containing aryl structures in the fields of medicines, pesticides, advanced materials and the like; and the aryl boronic acid compound preparation method reported in the disclosed literature has problems of harsh reaction conditions and high cost. A purpose of the invention is to provide amethod, wherein an aryl boron compound is formed by carrying out a reaction on a Grignard reagent and trialkyl borate under mild conditions, the composition of the aryl boron compound is converted from the main component diaryl borate into the main component aryl borate, and the aryl borate is hydrolyzed to obtain aryl boric acid, so that the preparation cost of the acyl aryl boric acid compound can be remarkably reduced, and the method has good practical application prospect.
-
Paragraph 0033-0036

(2020/01/25)

Bedford-type palladacycle-catalyzed miyaura borylation of aryl halides with tetrahydroxydiboron in water
A mild aqueous protocol for palladium catalyzed Miyaura borylation of aryl iodides, aryl bromides and aryl chlorides with tetrahydroxydiboron (BBA) as a borylating agent is developed. The developed methodology requires low catalyst loading of Bedford-type palladacycle catalyst (0.05 mol %) and works best under mild reaction conditions at 40 °C in short time of 6 h in water. In addition, our studies show that for Miyaura borylation using BBA in aqueous condition, maintaining a neutral reaction pH is very important for reproducibility and higher yields of corresponding borylated products. Moreover, our protocol is applicable for a broad range of aryl halides, corresponding borylated products are obtained in excellent yields up to 93% with 29 examples demonstrating its broad utility and functional group tolerance.
Zernickel, Anna,Du, Weiyuan,Ghorpade, Seema A.,Sawant, Dinesh N.,Makki, Arwa A.,Sekar, Nagaiyan,Eppinger, J?rg
p. 1842 - 1851
(2018/02/23)

Asymmetric Arylation of Imines Catalyzed by Heterogeneous Chiral Rhodium Nanoparticles
Asymmetric arylation of aldimines catalyzed by heterogeneous chiral rhodium nanoparticles has been developed. The reaction proceeded in aqueous media without significant decomposition of the imines by hydrolysis to afford chiral (diarylmethyl)amines in high yields with outstanding enantioselectivities. This catalyst system exhibited the highest turnover number (700) in heterogeneous catalysts reported to date for these reactions. The reusability of the catalyst was also demonstrated.
Yasukawa, Tomohiro,Kuremoto, Tatsuya,Miyamura, Hiroyuki,Kobayashi, Sh?
supporting information
p. 2716 - 2718
(2016/06/15)

Efficient metal-free photochemical borylation of aryl halides under batch and continuous-flow conditions
A rapid, chemoselective and metal-free C-B bond-forming reaction of aryl iodides and bromides in aqueous solution at low temperatures was discovered. This reaction is amenable to batch and continuous-flow conditions and shows exceptional functional group tolerance and broad substrate scope regarding both the aryl halide and the borylating reagent. Initial mechanistic experiments indicated a photolytically generated aryl radical as the key intermediate.
Chen, Kai,Zhang, Shuai,He, Pei,Li, Pengfei
p. 3676 - 3680
(2016/06/09)

Fast and Tight Boronate Formation for Click Bioorthogonal Conjugation
A new click bioorthogonal reaction system was devised to enable the fast ligation (kON≈340 m-1 s-1) of conjugatable derivatives of a rigid cyclic diol (nopoldiol) and a carefully optimized boronic acid partner, 2-methyl-5-carboxymethylphenylboronic acid. Using NMR and fluorescence spectroscopy studies, the corresponding boronates were found to form reversibly within minutes at low micromolar concentration in water, providing submicromolar equilibrium constant (Keq≈105-106 m-1). Efficient protein conjugation under physiological conditions was demonstrated with model proteins thioredoxin and albumin, and characterized by mass spectrometry and gel electrophoresis.
Akgun, Burcin,Hall, Dennis G.
supporting information
p. 3909 - 3913
(2016/03/19)

Benzosulfones as photochemically activated sulfur dioxide (SO2) donors
Sulfur dioxide (SO2) is a gaseous environmental pollutant which is routinely used in industry as a preservative and antimicrobial. Recent data suggests that SO2 may have value as a therapeutic agent. However, due to its gaseous nature, localizing SO2 generation is challenging. Herein, various 1,3-dihydrobenzo[c]thiophene 2,2-dioxides (benzosulfones) were prepared as candidates for photochemically activated sulfur dioxide (SO2) generation. These compounds were found to be stable in buffer but were photolysed upon irradiation with UV light to generate SO2. Our data indicates that photolysis of benzosulfones depends on substituents, and that the presence of electron donating groups results in an enhanced yield of SO2. This journal is
Malwal, Satish R.,Chakrapani, Harinath
p. 2399 - 2406
(2015/03/04)

Pyrene derivatives comprising heteroaryl amine group and organic light-emitting diode including the same
The present invention relates to a pyrene derivative represented by chemical formula A, and an organic light-emitting diode including the same. In the chemical formula A, substituents Z, Ar_1, Ar_2, R_1 to R_5, connecting groups L_1 and L_2, and X, m, p and q are the same as defined in a detailed description of the present invention.COPYRIGHT KIPO 2015
-
Paragraph 0331; 0351-0356

(2016/10/10)

An easy route to (hetero)arylboronic acids
An unprecedented spontaneous reactivity between diazonium salts and diboronic acid has been unveiled, leading to a versatile arylboronic acid synthesis directly from (hetero)arylamines. This fast reaction (35 min overall) tolerates a wide range of functional groups and is carried out under very mild conditions. The radical nature of the reaction mechanism has been investigated.
Erb, William,Hellal, Akila,Albini, Mathieu,Rouden, Jacques,Blanchet, Jerome
supporting information
p. 6608 - 6612
(2014/06/09)

Sequential one-pot access to molecular diversity through aniline aqueous borylation
On the basis of our recently reported aniline aqueous borylation, molecular diversity was achieved in a one-pot process by combining other reactions such as esterification, Suzuki-Miyaura coupling, hydrogenolysis, or Petasis borono-Mannich.
Erb, William,Albini, Mathieu,Rouden, Jacques,Blanchet, Jrme
p. 10568 - 10580
(2015/01/08)

Structure-activity study leading to identification of a highly active thienopyrimidine based EGFR inhibitor
Based on the thieno[2,3-d]pyrimidine scaffold, a series of new 4-amino-6-aryl thienopyrimidines have been prepared and evaluated as EGFR tyrosine kinase inhibitors. The in vitro activity was found to depend strongly on the substitution pattern in the 6-aryl ring, the stereochemistry, and the basicity at the secondary 4-amino group. A stepwise optimization by combination of active fragments led to the discovery of three structures with EGFR IC 50 50 of 0.3 nM towards EGFR and its mutants L858R and L861Q. Studies using human cancer cell lines and an EGFR-L858R reporter cell system revealed good cellular potency, verifying the identified thienopyrimidines as promising lead structures.
Bugge, Steffen,Kaspersen, Svein Jacob,Larsen, Synne,Nonstad, Unni,Bj?rk?y, Geir,Sundby, Eirik,Hoff, B?rd Helge
p. 354 - 374
(2014/03/21)

Mn-catalyzed aromatic C-H alkenylation with terminal alkynes
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
p. 1264 - 1267
(2013/03/14)

Nickel-catalyzed borylation of halides and pseudohalides with tetrahydroxydiboron [B2(OH)4]
Arylboronic acids are gaining increased importance as reagents and target structures in a variety of useful applications. Recently, the palladium-catalyzed synthesis of arylboronic acids employing the atom-economical tetrahydroxydiboron (BBA) reagent has been reported. The high cost associated with palladium, combined with several limitations of both palladium- and copper-catalyzed processes, prompted us to develop an alternative method. Thus, the nickel-catalyzed borylation of aryl and heteroaryl halides and pseudohalides using tetrahydroxydiboron (BBA) has been formulated. The reaction proved to be widely functional group tolerant and applicable to a number of heterocyclic systems. To the best of our knowledge, the examples presented here represent the only effective Ni-catalyzed Miyaura borylations conducted at room temperature.
Molander, Gary A.,Cavalcanti, Livia N.,Garcia-Garcia, Carolina
p. 6427 - 6439
(2013/07/26)

SYNTHESIS OF BORONIC ESTERS AND BORONIC ACIDS USING GRIGNARD REAGENTS
Boronic esters and boronic acids are synthesized at ambient temperature in an ethereal solvent by the reaction of Grignard reagents with a boron-containing substrate. The boron-containing substrate may be a boronic ester such as pinacolborane, neopentylglycolborane, or a dialkylaminoborane compound such as diisopropylaminoborane. The Grignard reagents may be preformed or generated from an alkyl, alkenyl, aryl, arylalkyl, heteroaryl, vinyl, or allyl halide compound and Mg°. When the boron-containing substrate is a boronic ester, the reactions generally proceed at room temperature without added base in about 1 to 3 hours to form a boronic ester compound. When the boron-containing substrate is a dialkylaminoborane compound, the reactions generally proceed to completion at 0°C in about 1 hour to form a boronic acid compound.
-
Paragraph 0102-0103; 0106

(2013/03/26)

Synthesis of phenylboronic acids in continuous flow by means of a multijet oscillating disc reactor system operating at cryogenic temperatures
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
p. 1121 - 1130
(2012/08/27)

Scope of the palladium-catalyzed aryl borylation utilizing bis-boronic acid
The Suzuki-Miyaura reaction has become one of the more useful tools for synthetic organic chemists. Until recently, there did not exist a direct way to make the most important component in the coupling reaction, namely the boronic acid. Current methods to make boronic acids often employ harsh or wasteful reagents to prepare boronic acid derivatives and require additional steps to afford the desired boronic acid. The scope of the previously reported palladium-catalyzed, direct boronic acid synthesis is unveiled, which includes a wide array of synthetically useful aryl electrophiles. It makes use of the newly available second generation Buchwald XPhos preformed palladium catalyst and bis-boronic acid. For ease of isolation and to preserve the often sensitive C-B bond, all boronic acids were readily converted to their more stable trifluoroborate counterparts.
Molander, Gary A.,Trice, Sarah L. J.,Kennedy, Steven M.,Dreher, Spencer D.,Tudge, Matthew T.
supporting information; experimental part
p. 11667 - 11673
(2012/09/05)

Palladium-catalyzed borylation of aryl and heteroaryl halides utilizing tetrakis(dimethylamino)diboron: One step greener
The palladium-catalyzed borylation of aryl and heteroaryl halides with a novel borylating agent, tetrakis(dimethylamino)diboron [(Me2N) 2B-B(NMe2)2], is reported. The method is complementary to the previously reported method utilizing bis-boronic acid (BBA) in that certain substrates perform better under one set of optimized reaction conditions than the other. Because tetrakis(dimethylamino)diboron is the synthetic precursor to both BBA and bis(pinacolato)diboron (B 2Pin2), the new method represents a more atom-economical and efficient approach to current borylation methods.
Molander, Gary A.,Trice, Sarah L. J.,Kennedy, Steven M.
supporting information
p. 4814 - 4817,4
(2012/12/12)

Reaction of grignard reagents with diisopropylaminoborane. Synthesis of alkyl, aryl, heteroaryl and allyl boronic acids from organo(diisopropyl)- aminoborane by a simple hydrolysis
Diisopropylaminoborane (BH2-N(iPr)2) is prepared by reacting lithium diisopropylaminoborohydride (iPr-LAB) with trimethylsilyl chloride (TMSCl). Aliphatic, aromatic, and heteroaromatic (diisopropylamino) boranes are readily synthesiz
Bailey, Christopher L.,Murphy, Chris L.,Clary, Jacob W.,Eagon, Scott,Gould, Naomi,Singaram, Bakthan
p. 331 - 341
(2013/08/23)

Lithium aminoborohydrides 17. Palladium catalyzed borylation of aryl iodides, bromides, and triflates with diisopropylaminoborane prepared from lithium diisopropylaminoborohydride
The Alcaraz-Vaultier borylation of aryl halides and triflates is reported utilizing diisopropylaminoborane (BH2N(iPr)2) prepared from the corresponding lithium aminoborohydride (LAB reagent). BH 2N(iPr)2, prepared by reacting lithium diisopropylaminoborohydride with trimethylsilyl chloride, provided the most consistent isolated yields from this reaction. Catalytic amounts of palladium dichloride produced the highest yields from aryl iodides, while catalytic tris(dibenzylideneacetone)dipalladium(chloroform) provided the best yields for aryl bromides and triflates. This route to boronic acids is mild enough to tolerate various functionalities and for the first time employs aryl triflates as substrates for the Alcaraz-Vaultier borylation. In addition, it was found that both boronic acid and ester compounds could be isolated from the reaction mixture utilizing simple work-up procedures. Treatment of the reaction intermediate with an acid/base work-up provided the corresponding boronic acid, while treating the same intermediate with a diol, such as neopentyl glycol, afforded the corresponding boronic ester.
Haddenham, Dustin,Bailey, Christopher L.,Vu, Chau,Nepomuceno, Gabby,Eagon, Scott,Pasumansky, Lubov,Singaram, Bakthan
experimental part
p. 576 - 583
(2011/03/18)

Iron trichloride promoted hydrolysis of potassium organotrifluoroborates
In the presence of iron trichloride, the hydrolysis of potassium organotrifluoroborates occurs smoothly at room temperature to afford the corresponding organoboronic acids in good to excellent yields. The hydrolysis is effective for aryltrifluoroborates as well as alkenyl- and alkyl- trifluoroborates.
Blevins, David W.,Yao, Min-Liang,Yong, Li,Kabalka, George W.
experimental part
p. 6534 - 6536
(2011/12/22)

A recyclable Au(I) catalyst for selective homocoupling of arylboronic acids: Significant enhancement of nano-surface binding for stability and catalytic activity
Au nanoparticles stabilized by polystyrene-co-polymethacrylic acid microspheres (PS-co-PMAA) were prepared and characterized via X-ray diffraction (XRD), and transmission electron microscope (TEM). The Au nanoparticles supported on the microspheres showed highly selective catalytic activity for homo-coupling reactions of arylboronic acids in a system of aryl-halides and arylboronic acids. X-ray photoelectron spectroscopy (XPS) spectra of the catalyst shows large amounts of Au(l) complexes band to the surface of the Au nanoparticles, which contributes to the selective homocoupling of the arylboronic acids. More importantly, this supported Au complex is a highly recyclable catalyst. The supported Au catalyst can be recycled and reused at least 6 times for a phenylboronic acid reactant, whereas the parent complex shows very low catalytic activity for this compound. The high catalytic activity of this material is attributed to: (1) the high surface to volume ratio which leads to more active sites being exposed to reactants; (2) the strong surface binding of the Au nanoparticle to the Au(1) complexes, which enhances both the stability and the catalytic activity of these complexes. Copyright
Zhang, Xin,Zhao, Haitao,Wang, Jianhui
experimental part
p. 5153 - 5160
(2011/12/15)

Introduction of allyi and prenyl side-chains into aromatic systems by suzuki cross-coupling reactions
This paper reports some studies aiming at the developement of a general protocol useful for the synthesis of allyl- and prenylaromatic compounds. The first part deals with, the preparation of boron reagents like arylboronic acids and their pinacol esters as well as of pinacol allyl- and prenylboronates. The second part of the paper is devoted to the use of these boron reagents in Suzuki-Miyaura cross-coupling reactions leading to allylation and prenylation of aromatic compounds. Of the six methods studied, the most promising re-suits were obtained by using the Pd2(dba)3-catalyzed reactions of arylboronic acids with allyl and prenyl bromides, that lead to the products of cross coupling in high yields (average 87%), and the reactions of aryl trifluoroborates with allyl and prenyl bromides catalyzed by Pd(OAc)2 that lead to the products of coupling in all cases in high yields (average 82%).
Gerbino, Dario C.,Mandolesi, Sandra D.,Schmalz, Hans-Guenther,Podesta, Julio C.
scheme or table
p. 3964 - 3972
(2010/02/27)

Efficient hydrolysis of organotrifluoroborates via silica gel and water
(Chemical Equation Presented) A general, mild, and efficient method for the hydrolysis of organotrifluoroborates to unveil boronic acids using silica gel and H2O was developed. This method proved to be tolerant of a broad range of aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates as well as structurally diverse aminomethylated organotrifluoroborates.As anticipated, electron-rich substrates provided the corresponding boronic acids more readily than electron-poor substrates, owing to the resonance-stabilized difluoroborane intermediate. The method developed was expanded further for the conversion of organotrifluoroborates to the corresponding boronate esters. 2009 American Chemical Society.
Molander, Gary A.,Cavalcanti, Livia N.,Canturk, Belgin,Pan, Po-Shen,Kennedy, Lauren E.
supporting information; experimental part
p. 7364 - 7369
(2010/01/16)

A MICROOPTIC GLUCOSE DETECTOR
Disclosed is a compound that fluoresces in the presence of saccharides, the compound having the formula wherein F designates a fluorophore, R is a lower aliphatic or aromatic group, n and m are each O, 1, or 2, n+m is the integer 2 or 3, p is an integer of 1 to about 30, and the moieties [CH2CH2]p and the benzene ring attached to the boron atom are substituted or unsubstituted. The present invention also provides a fully- integrated microfluidic system for detection of the fluorescence which comprises a light source; a self-assembled monolayer of a compound of the above formula coated on a gold surface that fluoresces in the presence of a saccharide; a light processor; and a detector.
-
Page/Page column 13

(2008/06/13)

A concise synthesis of novel naphtho[a]carbazoles and benzo[c]carbazoles
Starting from simple indole precursors the synthesis of naphtho[a]carbazoles and benzo[c]carbazoles is described. Key steps include the use of the Suzuki-Miyaura reaction to afford 2- or 3-aryl substituted indoles, as well as a potassium t-butoxide and light assisted aromatic ring-forming reaction.
Pathak, Rakhi,Nhlapo, Johanna M.,Govender, Sameshnee,Michael, Joseph P.,Van Otterlo, Willem A. L.,De Koning, Charles B.
p. 2820 - 2830
(2007/10/03)

Methodology for the synthesis of 1,2-disubstituted arylnaphthalenes from α-tetralones
α-Tetralones were initially converted into 1-bromo- dihydronaphthalene-2-carbaldehydes and 1-bromo-naphthalene-2-carbaldehydes. These precursors were then subjected to Suzuki coupling reactions to afford 1,2-disubstituted aryldihydronaphthalenes and 1,2-disubstituted arylnaphthalenes, respectively. The former products were oxidized with DDQ to give 1,2-disubstituted arylnaphthalenes.
Moleele, Simon S.,Michael, Joseph P.,De Koning, Charles B.
p. 2831 - 2844
(2007/10/03)

Formal intramolecular photoredox chemistry of meta-substituted benzophenones
(Chemical Equation Presented) Photolysis of 3-(hydroxymethyl)benzophenone (1) in aqueous solution (pH -4 M) conditions. Evidence suggests that the highly efficient (Φ ～ 0.6) reaction involves a unimolecular mechanism and an overall formal intramolecular photoredox process, which requires electronic communication between the 1,3-positions of the benzene ring, an unprecedented example of the photochemical meta effect. The photoredox reaction was not observed in organic solvents, where only photoreduction of the benzophenone moiety was observed.
Mitchell, Devin,Lukeman, Matthew,Lehnherr, Dan,Wan, Peter
p. 3387 - 3389
(2007/10/03)

Carbon-carbon bond-forming enantioselective synthesis of chiral organosilicon compounds by rhodium/chiral diene-catalyzed asymmetric 1,4-addition reaction
(Chemical Equation Presented) A new synthetic method for chiral organosilicon compounds through a rhodium-catalyzed asymmetric 1,4-addition of arylboronic acids to β-silyl α,β-unsaturated carbonyl compounds has been developed. By employing (R,R)-Bn-bod * as a ligand, a range of arylboronic acids can be coupled with these substrates in very high enantiomeric excess. The resulting β-silyl 1,4-adducts can be converted to β-hydroxy carbonyl compounds or allylsilanes while retaining their stereochemical information.
Shintani, Ryo,Okamoto, Kazuhiro,Hayashi, Tamio
p. 4757 - 4759
(2007/10/03)

Solvolysis and ring closure of quinone methides photogenerated from biaryl systems
A variety of biaryl quinone methides have been photogenerated with a range of efficiencies from biaryl precursors 4-6 and 8, 10, and 11, all having hydroxyl and hydroxymethyl substituents on alternate rings. These novel biaryl quinone methides, which cannot be readily generated via thermal chemistry, are trapped by added nucleophiles such as MeOH and ethanolamine; two that cannot undergo electrocyclic ring closure (from 8 and 11) are readily observable by nanosecond laser photolysis, with long wavelength maxima (λ max) of 600 and 520 nm, respectively. Photogenerated o,o′-biaryl quinone methides undergo electrocyclic ring closure to give the corresponding chromene (pyran) products in high yield. Since the precursor biaryl alcohols have highly twisted structures in the ground state (dihedral angle of up to 90° by molecular mechanics calculations), a significant twisting motion to planarity is required to achieve reaction. Using steady-state fluorescence studies, we present evidence to suggest that the mechanism of quinone methide formation may occur via one of the following mechanisms: (i) dissociation of the proton from ArOH that precedes twisting; or (ii) ArOH dissociation and twisting taking place either simultaneously or in quick succession.
Shi, Yijian,Wan, Peter
p. 1306 - 1323
(2007/10/03)

The synthesis of angularly fused polyaromatic compounds by using a light-assisted, base-mediated cyclization reaction
The synthesis of substituted polyaromatic compounds that contain at least four benzene rings fused together in an angular fashion is described. Suzuki coupling of 1-bromo-3,4-dihydronaphthalene-2-carbaldehyde with a number of aromatic boronic acids affords products such as 1-(1,4-dimethoxy-3-methyl-2-naphthyl)-3,4-dihydronaphthalene-2-carbaldehyde. Exposure of these dihydronaphthalenes to potassium tert-butoxide and DMF at 80°C yields polyaromatic compounds such as 9,14-dimethoxynaphtho[1,2-a]anthracene.
Pathak, Rakhi,Vandayar, Kantharuby,Van Otterlo, Willem A. L.,Michael, Joseph P.,Fernandes, Manuel A.,De Koning, Charles B.
p. 3504 - 3509
(2007/10/03)

Deprotection of pinacolyl boronate esters by transesterification with polystyrene-boronic acid
A mild, efficient method for the deprotection of pinacolyl organoboronate esters is described. Treatment of the organoboronate ester with excess polystyrene-boronic acid followed by filtration and evaporation of the solvent provides the corresponding organoboronic acid. Mild deprotection of pinacolyl boronate esters to the corresponding boronic acids was achieved in the presence of excess polystyrene-boronic acid via a transesterification process. The procedure allows for the cleavage of pinacolyl boronate esters in the presence of sensitive functional groups. Crown Copyright
Pennington, Thomas E.,Kardiman, Cynantya,Hutton, Craig A.
p. 6657 - 6660
(2007/10/03)

Dihydrobenzofuran and dihydrobenzothiophene 2,4-pentadienoic acid derivatives having selective activity for retinoid X (RXR) receptors
Compounds of the formula where the variables have the meaning defined in the specification, are specific or selective agonists of RXR retinoid receptors.
-
Page/Page column 29

(2010/01/31)

A new method for installation of aryl and alkenyl groups onto a cyclopentene ring and synthesis of prostaglandins
To construct a new strategy for synthesis of cyclopentanoids, the transition metal-catalyzed coupling reaction of cis 4-cyclopentene-1,3-diol monoacetate 1 with hard nucleophiles, RT-m, was investigated (eq 1 in Chart 1). Although preliminary experiments using PhZnCl, PhSnMe3, [Ph-B(Me)(OCH-(Me)CH(Me)O)]-Li+ (6a) (derived from boronate ester 4a (RT = Ph) and MeLi) in the presence of a palladium or a nickel catalyst resulted in production of unidentified compounds, enone 16, and/or ketone 17 or recovery of 1, a new borate 5a (derived from 4a and n-BuLi) in the presence of a nickel catalyst (NiCl2(PPh3)2) in THF at room temperature furnished the trans coupling products 2a (RT = Ph) and 3a (RT = Ph) in high combined yield, but with a low product ratio of 0.9:1. The ratio was improved to 13:1 by addition of t-BuCN and NaI into the reaction mixture. This is the first successful example of the reaction of 1 with a hard nucleophile, and the increase in the ratio, realized with the additives, is unprecedented. This reagent system (borate 5 (1.2-1.8 equiv), NiCl2-(PPh3)2 (5-10 mol%), t-BuCN (2-5 equiv), NaI (0.5-1 equiv), THF, room temp) was further investigated with aryl borates 5b-g and alkenyl borates 5h-n to afford 2b-n in moderate to good yields (52-89%) with practically acceptable levels of the regioselectivity (5 ～ 21:1), thus establishing the generality of the reaction (Table 2, eqs 6 and 7). Starting with the products of the coupling reaction, syntheses of the prostaglandin intermediates 13 and 14 (for 11-deoxy-PGE2 and PGA2) and Δ7-PGA1 methyl ester (15) were accomplished efficiently. During these investigations, LDA, LiCA, and LHMDS were found to be equally efficient bases for aldol reaction at the α′ (α prime) position of cyclopentenones 39, 40, and 41 (Table 3).
Kobayashi, Yuichi,Murugesh, Modachur G.,Nakano, Miwa,Takahisa, Eisuke,Usmani, Shahid B.,Ainai, Takayuki
p. 7110 - 7123
(2007/10/03)

Phosphine ligands metal complexes and compositions thereof for cross-coupling reactions
The present invention discloses new efficient processes for various bond forming reactions, including Suzuki reactions and aryl aminations. Organic compounds (e.g., ligands), their metal complexes and compositions using those compounds, provide useful catalysts. The invention also relates to performing Suzuki cross coupling reactions with unreactive aryl-chlorides.
-
(2008/06/13)

A novel method for the synthesis of substituted naphthalenes and phenanthrenes
A new method for the synthesis of substituted naphthalenes and phenanthrenes was discussed. A formal synthesis of tanshinone I was also studied. Natural products that contain a naphthalene or phenanthrene nucleus often exhibit biological activity, which makes them attractive targets in organic synthesis. The results showed that the reaction can be proceed through at least two different pathways.
De Koning, Charles B.,Michael, Joseph P.,Rousseau, Amanda L.
p. 787 - 797
(2007/10/03)

Transmetallations between aryltrialkyltins and borane: Synthesis of arylboronic acids and organotin hydrides
Aryltrialkyltin compounds react with borane in THF to give mixtures of trialkyltin hydrides and arylboranes, which on hydrolysis give arylboronic acid in high yields. The arylboronic acids are easily separated and obtained free of organotins.
Faraoni,Koll,Mandolesi,Zú?iga,Podestá
p. 236 - 238
(2007/10/03)

Therapeutic amines
Compounds of formula I, and their pharmaceutically acceptable salts, STR1 in which R1 and R2 are hydrogen, alkyl, cycloalkyl, cycloalkylalkyl, phenylalkyl or alkenyl; or NR1 R2 is a heterocyclic group; A is trimethylene optionally substituted by alkyl and the phenyl ring is optionally substituted by substituents such as halogeno, alkenyl, amino, cyano, ureido, alkyl, carbamoylalkyl, alkanoylamino, alkoxycarbonyl, N-alkyl-alkanoylamino, alkanoyl and amines thereof; are inhibitors of squalene synthese and hence useful in treating diseases in which a lowering of cholesterol is desirable. As well as the use of these compounds in medicine, novel compounds, processes for their preparation and pharmaceutical compositions are also referred to.
-
(2008/06/13)

Synthesis and X-ray crystal structure investigation of a potential boronate affinity chromatography ligand o-boronobenzalmethoxyamine
A potential boronate affinity chromatography ligand o-boronobenzalmethoxyamine (IV) and its precursor of the distinguishing functional group.In addition, 11B NMR data confirmed the lack of any coordination between the boron and oxygen atoms in the boronic acid compounds III and IV and the catachol ester derivative (V) of IV. o-Formylbenzeneboronic acid (III) crystallizes in space group P21/n with a = 3.883(1), b = 13.225(1), c = 14.029(2) Angstroem, β = 92.16(1) deg, and four molecules per unit cell. o-Boronobenzalmethoxyamine (IV) crystallizes in space group Pccn with a = 14.158(2), b = 17.156(1), c = 7.734(2) Angstroem, and eight molecules per unit cell.Selected bond distances and angles are tabularized.KEY WORDS: Boronate, o-Boronobenzalmethoxyamine, o-formylbenzeneboronic acid(III).
Scouten, W. H.,Liu, X.-C.,Khangin, N.,Mullica, D. F.,Sappenfield, E. L.
p. 621 - 626
(2007/10/02)

THE REACTIONS OF DIBORANE WITH ARYL-ORGANOTIN COMPOUNDS
A number of tetraaryltin compounds, Ar4Sn (where Ar = phenyl, o- and p-tolyl, and p-chlorophenyl) and tryphenyltin compounds, PH3SnX (where X = Cl, H, OH, OCOCH3 and OCOCF3) have been treated with diborane in tetrahydrofuran.Transmetallation occurs in which one or more aryl groups are transferred to boron.The organoboron intermediates give phenols upon oxidation and boronic and borinic acids upon hydrolysis.Pyridine complexes of organoboranes have also been isolated.
Pickles, G. M.,Spencer, T.,Thorpe, F. G.,Chopa, A. B.,Podesta, J. C.
p. 7 - 16
(2007/10/02)

REACTIONS OF DIBORANE WITH LITHIUM DIARYLCUPRATES AND ORGANOCADMIUM COMPOUNDS
Lithium diarylcuprates react with diborane to form as intermediates organoboron compounds, which can be converted into phenols, arylboronic acids and arylamines; complexes of triarylboron compounds can also be isolated.Preliminary studies show that organo
Bullen, N. P.,Chiheru, K. S.,Thorpe, F. G.
p. 147 - 154
(2007/10/02)