- A new polymorph of tri(p-tolyl)boroxine
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A new orthorhombic polymorph of tri(p-tolyl)boroxine (Pmn21) with relatively short intermolecular B-O distances of 3.321 A was crystallized from CDCl3 at ambient temperature. The crystal structure of the orthorhombic polymorph of tri
- Haberecht, Monika C.,Bolte, Michael,Wagner, Matthias,Lerner, Hans-Wolfram
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Read Online
- Direct Imide Formation from Thiophene Dicarboxylic Acids Gives Expanded Side-Chain Selection in Thienopyrrolediones
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The synthesis of thienopyrroledione (TPD) has been updated to reduce the number of synthetic steps, remove hazardous and toxic reagents, reduce the amount of byproduct waste, and reduce the use of solvents when unnecessary. Diverse functionalization is possible, introducing 16 examples in yields from 34% to 95%. This reaction scheme was shown to be general for thiophene imides, and a more thorough exploration into side chain engineering is presented with TPD acceptors often used in organic electronic applications.
- Wolfe, Rylan M. W.,Reynolds, John R.
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Read Online
- Synthesis of borophosphonate cage compounds: Influence of substituent and concentration effects on product distribution in condensation reactions of aryl phosphonic acids and boronic acids
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Aryl borophosphonate cage compounds [ArPO3BAr′]n with n = 4 or 6 were synthesized by condensation reactions of ArP(O)(OH)2 and Ar′B(OH)2. (3,5-tBu2-Ph)P(O)(OH)2 (1) reacts with a
- Liu, Qian,Contrella, Nathan D.,Filatov, Alexander S.,Jordan, Richard F.
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Read Online
- Nickel- and Palladium-Catalyzed Cross-Coupling Reactions of Organostibines with Organoboronic Acids
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A strategy for the formation of antimony-carbon bond was developed by nickel-catalyzed cross-coupling of halostibines. This method has been applied to the synthesis of various triaryl- and diarylalkylstibines from the corresponding cyclic and acyclic halostibines. This protocol showed a wide substrate scope (72 examples) and was compatible to a wide range of functional groups such as aldehyde, ketone, alkene, alkyne, haloarenes (F, Cl, Br, I), and heteroarenes. A successful synthesis of arylated stibine 3 a in a scale of 34.77 g demonstrates high synthetic potential of this transformation. The formed stibines (R3Sb) were then used for the palladium-catalyzed carbon–carbon bond forming reaction with aryl boronic acids [R?B(OH)2], giving biaryls with high selectivity, even the structures of two organomoieties (R and R′) are very similar. Plausible catalytic pathways were proposed based on control experiments.
- Zhang, Dejiang,Le, Liyuan,Qiu, Renhua,Wong, Wai-Yeung,Kambe, Nobuaki
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supporting information
p. 3104 - 3114
(2020/12/11)
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- Copper-Catalyzed Asymmetric Arylation of N-Heteroaryl Aldimines: Elementary Step of a 1,4-Insertion
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Copper complexes of monodentate phosphoramidites efficiently promote asymmetric arylation of N-azaaryl aldimines with arylboroxines. DFT calculations and experiments support an elementary step of 1,4-insertion in the reaction pathway, a step in which an aryl-copper species adds directly across four atoms of C=N?C=N in the N-azaaryl aldimines.
- Wu, Chunlin,Qin, Xurong,Moeljadi, Adhitya Mangala Putra,Hirao, Hajime,Zhou, Jianrong Steve
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supporting information
p. 2705 - 2709
(2019/02/06)
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- Recyclable, Strong, and Highly Malleable Thermosets Based on Boroxine Networks
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Traditional thermoset materials have favorable material properties but are unable to reprocess and are difficult to recycle. Small molecule boroxines have been shown to undergo a reversible exchange reaction. Herein we employ boroxine as dynamic cross-lin
- Ogden, William A.,Guan, Zhibin
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supporting information
p. 6217 - 6220
(2018/05/23)
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- Kinetics and Mechanism of the Palladium-Catalyzed Oxidative Arylating Carbocyclization of Allenynes
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Pd-catalyzed C-C bond-forming reactions under oxidative conditions constitute a class of important and widely used synthetic protocols. This Article describes a mechanistic investigation of the arylating carbocyclization of allenynes using boronic acids and focuses on the correlation between reaction conditions and product selectivity. Isotope effects confirm that either allenic or propargylic C-H activation occurs directly after substrate binding. With an excess of H2O, a triene product is selectively formed via allenic C-H activation. The latter C-H activation was found to be turnover-limiting and the reaction zeroth order in reactants as well as the oxidant. A dominant feature is continuous catalyst activation, which was shown to occur even in the absence of substrate. Smaller amounts of H2O lead to mixtures of triene and vinylallene products, where the latter is formed via propargylic C-H activation. The formation of triene occurs only in the presence of ArB(OH)2. Vinylallene, on the other hand, was shown to be formed by consumption of (ArBO)3 as a first-order reactant. Conditions with sub-stoichiometric BF3·OEt2 gave selectively the vinylallene product, and the reaction is first order in PhB(OH)2. Both C-H activation and transmetalation influence the reaction rate. However, with electron-deficient ArB(OH)2, C-H activation is turnover-limiting. It was difficult to establish the order of transmetalation vs C-H activation with certainty, but the results suggest that BF3·OEt2 promotes an early transmetalation. The catalytically active species were found to be dependent on the reaction conditions, and H2O is a crucial parameter in the control of selectivity.
- Bartholomeyzik, Teresa,Pendrill, Robert,Lihammar, Richard,Jiang, Tuo,Widmalm, G?ran,B?ckvall, Jan-E.
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supporting information
p. 298 - 309
(2018/01/17)
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- Palladium(II)-Catalyzed Enantioselective Synthesis of α-(Trifluoromethyl)arylmethylamines
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We describe a method for the synthesis of α-(trifluoromethyl)arylmethylamines that consists of the palladium(II)-catalyzed addition of arylboroxines to imines derived from trifluoroacetaldehyde. Palladium acetate is used as a catalyst with electron-neutral or electron-rich arylboroxines, and it was found that addition of an ammonium or silver salt was crucial to promote the reaction of electron-poor boroxines. With (S)-t-Bu-PyOX as the chiral ligand, this method delivers a variety of α-trifluoromethylated amines in 57-91% yield and with greater than 92% ee in most cases.
- Johnson, Thomas,Luo, Bo,Lautens, Mark
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p. 4923 - 4930
(2016/07/06)
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- Rhodium-Catalyzed Asymmetric Arylation/Defluorination of 1-(Trifluoromethyl)alkenes Forming Enantioenriched 1,1-Difluoroalkenes
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The reaction of 1-(trifluoromethyl)alkenes (CF3CH=CHR) with arylboroxines (ArBO)3 in the presence of a chiral diene-rhodium catalyst gave high yields of chiral 1,1-difluoroalkenes (CF2=CHC?HArR) with high enantioselectivity (≥95% ee). The reaction is assumed to proceed through β-fluoride elimination of a β,β,β-trifluoroalkylrhodium intermediate that is generated by arylrhodation of the 1-(trifluoromethyl)alkene.
- Huang, Yinhua,Hayashi, Tamio
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supporting information
p. 12340 - 12343
(2016/10/07)
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- Expanding the structural diversity of Bcr-Abl inhibitors: Hybrid molecules based on GNF-2 and Imatinib
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In order to expand the structural diversity of Bcr-Abl inhibitors, twenty hybrids (series E and P) have been synthesized and characterized based on Imatinib and GNF-2. Their biological activities were evaluated in vitro against human leukemia cells. Most compounds exhibited potent antiproliferative activity against K562 cells, especially for compounds E4, E5 and E7. Furthermore, these new hybrids were also screened for Abl kinase inhibitory activity, and some of them inhibited Abl kinase with low micromolar IC50 values. In particular, compound P3 displayed the most potent activity with IC50 value of 0.017 μM comparable with that of Imatinib. Molecular docking studies indicated that these novel hybrids fitted well with the active site of Bcr-Abl. These results suggested the great potential of these compounds as novel Bcr-Abl inhibitors.
- Pan, Xiaoyan,Dong, Jinyun,Shao, Ruili,Su, Ping,Shi, Yaling,Wang, Jinfeng,He, Langchong
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supporting information
p. 4164 - 4168
(2015/11/03)
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- Asymmetric Synthesis of Triarylmethanes by Rhodium-Catalyzed Enantioselective Arylation of Diarylmethylamines with Arylboroxines
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The reaction of racemic diarylmethylamines, (Ar1Ar2CHNR2), where Ar1 is substituted with a 2-hydroxy group, with arylboroxines (Ar3BO)3 in the presence of a chiral diene-rhodium catalyst gave high yields of chiral triarylmethanes (Ar1Ar2CH?Ar3) with high enantioselectivity (up to 97% ee). The reaction is assumed to proceed through o-quinone methide intermediates which undergo Rh-catalyzed asymmetric 1,4-addition of the arylboron reagents.
- Huang, Yinhua,Hayashi, Tamio
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supporting information
p. 7556 - 7559
(2015/07/01)
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- Direct Amidation of N-Boc- and N-Cbz-Protected Amines via Rhodium-Catalyzed Coupling of Arylboroxines and Carbamates
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N-Boc- and N-Cbz-protected amines are directly converted into amides by a novel rhodium-catalyzed coupling of arylboroxines and carbamates, replacing the traditional two-step deprotection-condensation sequence. Both protected anilines and aliphatic amines are efficiently transformed into a wide variety of secondary benzamides, including sterically hindered and electron-deficient amides, as well as in the presence of acid-labile and reducible functional groups.
- Lim, Diane S. W.,Lew, Tedrick T. S.,Zhang, Yugen
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supporting information
p. 6054 - 6057
(2016/01/09)
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- Cross-coupling synthesis of methylallyl alkenes: Scope extension and mechanistic study
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Cross-coupling reactions between 2-methyl-2-propen-1-ol and various boronic acids are used to obtain aromatic-(2-methylallyl) derivatives. However, deboronation or isomerization side reactions may occur for several boronic acids. We describe herein the synthesis of original alkenes with good yields under mild reaction conditions that decrease these side reactions. The scope of this environmentally benign reaction is thereby extended to a wide variety of boronic acids. A mechanistic study was conducted and suggested a plausible catalytic cycle mechanism, pointing to the importance of the Lewis acidity of the boronic acid used.
- Tabélé, Clémence,Curti, Christophe,Kabri, Youssef,Primas, Nicolas,Vanelle, Patrice
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p. 22890 - 22899
(2016/01/25)
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- Enantioselective, nickel-catalyzed suzuki cross-coupling of quinolinium ions
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Quinolinium ions are engaged in an asymmetric, Ni-catalyzed Suzuki cross-coupling to yield 2-aryl- and 2-heteroaryl-1,2-dihydroquinolines. Key to the development of this method is the use of a Ni(II) precatalyst that activates without the need for strong reductants or high temperatures. The Ni-iminium activation mode is demonstrated as an exceptionally mild pathway to generate enantioenriched products from racemic starting materials.
- Shields, Jason D.,Ahneman, Derek T.,Graham, Thomas J. A.,Doyle, Abigail G.
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supporting information
p. 142 - 145
(2014/01/23)
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- Efficient palladium-catalyzed suzuki-miyaura reactions using phenolic schiff base ligands under ambient conditions in aqueous media
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The palladium complexes of a series of simple Schiff base ligands with or without phenolic hydroxyl groups have been found to be the excellent catalysts for the Suzuki-Miyaura reactions of aryl iodides, aryl bromides and activated aryl chlorides under ambient conditions in aqueous ethanol media. The introduction of phenolic hydroxyl and/or pyridine groups to the ligands increased the catalytic activity. Under optimal reaction conditions, satisfactory to excellent yields of biaryls were obtained with a wide range of substrates for relatively low loadings of catalyst. Graphical Abstract: Phenolic hydroxyl group and N4-type Schiff base ligands (L1-2) have been proven to be the excellent catalysts for the Suzuki-Miyaura reactions of aryl iodides, aryl bromides and activated aryl chlorides in aqueous ethanol under ambient. Furthermore, a diverse choice of functionalized arylboronic acids bearing difluoro, trifluoro and trifluoromethyl substituents were successfully coupled (>97 %)[Figure not available: see fulltext.].
- Zhou, Zhonggao,Zhou, Zhenyun,Chen, Aichen,Zhou, Xiuhua,Qi, Qi,Xie, Yongrong
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p. 401 - 405
(2013/06/05)
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- Rhodium-catalyzed asymmetric hydroarylation of 3-pyrrolines giving 3-arylpyrrolidines: Protonation as a key step
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A hydroxorhodium complex coordinated with (R)-segphos was found to catalyze the hydroarylation of 3-pyrrolines with arylboroxines under neutral conditions to give 3-arylpyrrolidines with high enantioselectivity in high yields.
- So, Chau Ming,Kume, Satoshi,Hayashi, Tamio
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supporting information
p. 10990 - 10993
(2013/08/23)
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- Programmed selective sp2 C-O bond activation toward multiarylated benzenes
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A variety of important multiarylated benzenes were efficiently synthesized from phloroglucinol derivatives 1 through sequential cross-couplings via Pd-catalyzed C-OTs, Ni-catalyzed C-OC(O)NEt2, and C-OMe bond activation. High selectivity was achieved based on the rational design and inherent diversity in the reactivity of different C-O bonds.
- Zhao, Fei,Zhang, Yun-Fei,Wen, Jing,Yu, Da-Gang,Wei, Jiang-Bo,Xi, Zhenfeng,Shi, Zhang-Jie
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supporting information
p. 3230 - 3233
(2013/07/26)
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- Palladium(II)-catalyzed enantioselective synthesis of α- (trifluoromethyl)arylmethylamines
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Trifluoromethylacetaldimines, generated in situ from the corresponding N,O-acetals, undergo 1,2-addition of arylboroxines under palladium(II) catalysis to generate a variety of α-(trifluoromethyl)arylmethylamines with good to high enantioselectivity (up to 97% ee). The pyridine-oxazolidine (PyOX) class of ligands was found to be particularly suitable for this transformation, which proceeds without exclusion of ambient air and moisture.
- Johnson, Thomas,Lautens, Mark
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supporting information
p. 4043 - 4045
(2013/09/12)
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- Rhodium(I)/diene-catalyzed addition reactions of arylborons with ketones
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Rh(I)/diene-catalyzed addition reactions of arylboroxines/arylboronic acids with unactivated ketones to form tertiary alcohols in good to excellent yields are described. By using C2-symmetric (3aR,6aR)-3,6-diaryl-1,3a,4,6a- tetrahydropentalenes as ligands, the asymmetric version of such an addition reaction, with up to 68% ee, was also realized.
- Liao, Yuan-Xi,Xing, Chun-Hui,Hu, Qiao-Sheng
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supporting information; experimental part
p. 1544 - 1547
(2012/06/05)
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- Rh-catalyzed addition of arylboroxines to cyclic N -(Isopropanesulfinyl) ketimines
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Arylboroxines, which are easily accessed by drying commercially available arylboronic acids, are added to N-(isopropanesulfinyl)ketimines derived from cyclohexanone, N-Boc-piperidin-4-one, and tetrahydropyran-4-one in high yields and with excellent functional group compatibility via rhodium catalysis. These results contrast with additions to the corresponding ketimines incorporating the larger N-tert-butanesulfinyl group, which give considerably lower yields. Efficient two-step preparation of racemic isopropanesulfinamide from inexpensive isopropyl disulfide and recycling of the isopropanesulfinyl group from the addition products are also described.
- Jung, Hyung Hoon,Buesking, Andrew W.,Ellman, Jonathan A.
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p. 9593 - 9600,8
(2012/12/12)
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- Rh-catalyzed addition of arylboroxines to cyclic N -(Isopropanesulfinyl) ketimines
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Arylboroxines, which are easily accessed by drying commercially available arylboronic acids, are added to N-(isopropanesulfinyl)ketimines derived from cyclohexanone, N-Boc-piperidin-4-one, and tetrahydropyran-4-one in high yields and with excellent functional group compatibility via rhodium catalysis. These results contrast with additions to the corresponding ketimines incorporating the larger N-tert-butanesulfinyl group, which give considerably lower yields. Efficient two-step preparation of racemic isopropanesulfinamide from inexpensive isopropyl disulfide and recycling of the isopropanesulfinyl group from the addition products are also described.
- Jung, Hyung Hoon,Buesking, Andrew W.,Ellman, Jonathan A.
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p. 9593 - 9600
(2013/01/15)
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- Kinetic and spectroscopic studies of aerobic copper(II)-catalyzed methoxylation of arylboronic esters and insights into aryl transmetalation to copper(II)
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We previously reported a preliminary mechanistic study of aerobic Cu(OAc)2-catalyzed methoxylation of 4-tolylboronic ester (King et al. J. Am. Chem. Soc., 2009, 131, 5044-5045), which revealed that aryl transmetalation from the boronic ester to CuII is the turnover-limiting step. In the present study, more thorough kinetic and spectroscopic studies provide additional insights into the transmetalation pathway and identity of the CuII catalyst resting state(s). EPR spectroscopic studies show that at least two copper(II) species are present under catalytic conditions, and their relative populations vary as a function of reaction time and acidity of the arylboronic ester and are influenced by addition of acetic acid or acetate to the reaction mixture. Analysis of kinetic data and 11B NMR and EPR spectra under diverse reaction conditions suggests that aryl transmetalation occurs from a tetracoordinate, anionic boronate to a cationic CuII species, mediated by a methoxide bridge.
- King, Amanda E.,Ryland, Bradford L.,Brunold, Thomas C.,Stahl, Shannon S.
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p. 7948 - 7957
(2013/01/16)
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- Bis-sulfamyl imines: Potent substrates for asymmetric additions of arylboroxines under rhodium catalysis
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Bis-sulfamyl imines are shown to be potentially ideal substrates for rhodium-catalysed asymmetric additions of arylboron nucleophiles as they show: (i) near perfect enantioselectivities (11 examples, 98-99+% ee), (ii) good to excellent diastereoselectivities (10-32:1 rac:meso), and (iii) high functional group tolerance in removal of the low molecular weight protecting group via mild heating in aqueous pyridine.
- Crampton, Rosemary,Woodward, Simon,Fox, Martin
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supporting information; experimental part
p. 903 - 906
(2011/06/19)
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- Ruthenium-catalyzed conversion of sp3 C-O bonds in ethers to C-C bonds using triarylboroxines
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Catalytic conversion of unreactive sp3 C-O bonds in alkyl ethers to C-C bonds is described. Alkyl ethers bearing 2- or 4-pyridyl groups were coupled with triarylboroxines in the presence of a ruthenium catalyst. Triarylboroxines bearing a variety of functional groups including electron-withdrawing and -donating groups can be used for the reaction. No additional base was required for the coupling with the organoboron reagents, and base-sensitive groups can be tolerated. The reaction is considered to proceed via dehydroalkoxylation followed by addition of triarylboroxines to form C-C bonds.
- Ogiwara, Yohei,Kochi, Takuya,Kakiuchi, Fumitoshi
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supporting information; experimental part
p. 3254 - 3257
(2011/08/02)
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- Highly functional group compatible Rh-catalyzed addition of arylboroxines to activated N-tert-butanesulfinyl ketimines
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The rhodium-catalyzed addition of readily accessible arylboroxines to N-tert-butanesulfinyl ketimines derived from oxetan-3-one, N-Boc-azetidin-3-one, and isatins proceeds in high yields with excellent functional group compatibility. Moreover, high diastereoselectivities are observed for the additions to the N-sulfinyl ketimines derived from isatins.
- Jung, Hyung Hoon,Buesking, Andrew W.,Ellman, Jonathan A.
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supporting information; experimental part
p. 3912 - 3915
(2011/09/16)
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- Asymmetric additive-free aryl addition to aldehydes using perhydrobenzoxazines as ligands and boroxins as aryl source
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A highly efficient enantioselective aryl addition to aldehydes using boroxins as aryl source and conformationally restricted perhydro-1,3- benzoxazines as ligands is reported. Both enantiomeric forms of chiral arylphenylmethanols and 1,1′-disubstituted diarylmethanols are afforded with excellent yields and enantioselectivities using the same ligand by means of an appropriate combination of boroxin and aromatic aldehyde. The enantiocontrol is not significantly influenced by electronic effects or steric hindrance, even with substituted boroxins. Very homogeneous ee's are reached when substituted arylboroxins are employed, without the use of any class of additive or pre-treatment.
- Infante, Rebeca,Nieto, Javier,Andres, Celia
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body text
p. 6691 - 6699
(2011/11/04)
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- CuCl/bipyridine-catalyzed addition reactions of arylboroxines with aldehydes, α,β-unsaturated ketones, and N-tosyl aldimines
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CuCl/bipyridine-catalyzed addition reactions of arylboroxines with aldehydes and α,β-unsaturated ketones at elevated temperatures were described. By using the microwave energy, CuCl/bipyridine-catalyzed addition reactions of arylboroxines with aldimines were also realized.
- Liao, Yuan-Xi,Hu, Qiao-Sheng
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body text
p. 7602 - 7607
(2011/11/12)
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- Nickel-catalyzed efficient and practical Suzuki-Miyaura coupling of alkenyl and aryl carbamates with aryl boroxines
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(Figure Presented) Suzuki-Miyaura coupling of unactivated alkenyl carbamates Is described to construct polysubstituted olefins. The developed process is also suitable for heteroaromatic and even electron-rich aromatic carbamates.
- Xu, Li,Li, Bi-Jie,Wu, Zhen-Hua,Lu, Xing-Yu,Guan, Bing-Tao,Wang, Bi-Qin,Zhao, Ke-Qing,Shi, Zhang-Jie
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supporting information; experimental part
p. 884 - 887
(2010/04/29)
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- Ni(COD)2/4-ClC6H4COR-catalyzed addition reactions of arylboroxines with aldehydes
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Ni(COD)2/4-ClC6H4COR (R = H, CH3, Ph) was found to be an efficient catalyst system for the addition reactions of arylboroxines with aromatic and aliphatic aldehydes. The catalytically active species for Ni(COD)2/4-ClC6H4COR catalyst systems was likely to be their oxidative addition adducts, 4-RCOC6H4Ni(II)Cl(COD) complexes.
- Xing, Chun-Hui,Hu, Qiao-Sheng
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supporting information; experimental part
p. 924 - 927
(2010/05/18)
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- Novel rhodamine dyes via suzuki coupling of xanthone triflates with arylboroxins
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Novel rhodamine dyes were prepared from xanthone precursors in a 'one-pot' procedure via reaction of the xanthone with trifluoromethanesulfonic anhydride followed by Pd-mediated Suzuki coupling between the xanthone triflate and an arylboroxin. Rhodamines with 9-(3- or 4-carboxyphenyl) and 9-(3-nitrophenyl) substituents were prepared by this procedure. The procedure also works well with thio- and selenoxanthones, but not with telluroxanthones. Georg Thieme verlag Stuttgart.
- Calitree, Brandon D.,Detty, Michael R.
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scheme or table
p. 89 - 92
(2010/07/16)
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- Construction of polysubstituted olefins through Ni-Catalyzed direct activation of Alkenyl C-O of substituted alkenyl acetates
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(Figure Presented) Reliable companion: For the first time cross-coupling between alkenyl acetates and arylboroxines/PhZnCl has been developed via Ni catalysis. Alkenyl acetates could be well-differ-entiated from aryl acetates (see scheme). This reliable method provides a convenient pathway to construct polysubstituted styrene derivatives.
- Sun, Chang-Liang,Yang, Wang,Xiao, Zhou,Wu, Zhen-Hua,Li, Bi-Jie,Guan, Bing-Tao,Shi, Zhang-Jie
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supporting information; body text
p. 5844 - 5847
(2010/09/03)
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- Chiral 1,1′-binaphthylazepine-derived amino alcohol catalyzed asymmetric aryl transfer reactions with boroxine as aryl source
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Using chiral 1,1′-binaphthylazepine-derived amino alcohol as catalyst, the direct addition of in situ prepared arylzinc (with triphenylboroxine as aryl source) to various aryl aldehydes can afford optically active diarylmethanols in high yields and enantioselectivities (up to 96%).
- Liu, Can,Guo, Zong-Liang,Weng, Jiang,Lu, Gui,Chan, Albert S. C.
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experimental part
p. 159 - 164
(2010/09/04)
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- Arylation and vinylation of α-diazocarbonyl compounds with boroxines
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An alternative approach for α-arylation and α-vinylation of carbonyl compounds is described: reaction between aryl-or vinylboroxines with α-diazocarbonyl compounds leads to the formation of α-arylated or α-vinylated carbonyl compounds under mild conditions.
- Peng, Cheng,Zhang, Wei,Yan, Guobing,Wang, Jianbo
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supporting information; experimental part
p. 1667 - 1670
(2009/08/07)
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- Steric tuning of the amidomonophosphane-rhodium(l) catalyst in asymmetric addition of arylboroxines to n-phosphinoyl aldimines
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Highly enantioselective rhodium-catalyzed addition of arylboroxlnes to N-phosphinoylaldimines was realized by the steric tuning of a dlphenylphosphorus moiety to a di(o-tolyl)phosphorus moiety of a chiral amidomonophosphane. The presence of MS 4 A in a 5:1 solvent mixture of dioxane-propanol was essential to afford the corresponding dlarylmethylamines In high yield.
- Hao, Xinyu,Kuriyama, Masami,Chen, Qian,Yamamoto, Yasutomo,Yamada, Ken-Ichi,Tomioka, Kiyoshi
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body text
p. 4470 - 4473
(2009/12/24)
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- Rhodium catalyzed reaction of internal alkynes with organoborons under CO atmosphere: a product tunable reaction
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Alkynes react with organoborons under a CO atmosphere in the presence of a rhodium(I) catalyst to afford mainly 5-aryl-2(5H)-furanones, α,β-unsaturated ketones, and indanones. The product selectivity can be tuned by modifying the reaction conditions.
- Artok, Levent,Ku?, Melih,Aksin-Artok, ?zge,Dege, Fatma Nurcan,?zkilin?, Fatma Yelda
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experimental part
p. 9125 - 9133
(2010/01/16)
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- N,N-diethyl O-carbamate: Directed metalation group and orthogonal Suzuki-Miyaura cross-coupling partner
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(Chemical Equation Presented) The first Suzuki-Miyaura cross-coupling of an aryl O-carbamate, a versatile and powerful directed metalation group (DMG) in directed ortho metalation (DoM) chemistry, is described using the inexpensive, bench-stable catalyst NiCl2(PCy3)2. Broad synthetic scope and good efficiency are demonstrated for aryl and heteroaryl O-carbamates. The role of water and hydrolysis equilibrium between free boronic acid and boroxine was established to be a crucial parameter for this transformation. When combined with DoM and traditional Pd-catalyzed Suzuki-Miyaura strategies, the methodology offers concise routes to uniquely substituted molecules, avoiding the need for protection/deprotection of the phenol and the use of strongly nucleophilic cross-coupling partners.
- Antoft-Finch, Aurora,Blackburn, Tom,Snieckus, Victor
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supporting information; experimental part
p. 17750 - 17752
(2010/03/25)
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- METHOD FOR THE PRODUCTION OF LOSARTAN
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The invention relates to a novel method for the production of losartan, an imidazol derivative with the chemical name 2-n-butyl-4-chloro-5-hydroxymethyl-1-{[2'-(1H-tetrazol-5-yl)biphenyl-4-]methyl}imidazol and the pharmacologically active salts thereof. The invention also relates to novel intermediate products which are suitable for the production of losartan, and to novel methods for the production of intermediate compounds which are suitable for the production of losartan. One aspect of the invention is a method for the production of a compound of general formula (I), which can arise as an intermediate step in the inventive representation of losartan.
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Page/Page column 20; 31
(2008/06/13)
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- Efficient synthesis of valsartan, a nonpeptide angiotensin II receptor antagonist
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A highly efficient and convergent approach to the synthesis of the angiotensin II receptor antagonist valsartan (1), one of the most important agents used in antihypertensive therapy today, is described. Directed ortho-metalation of 4-bromotoluene provides the key boronic acid intermediate 11 which was subjected to palladium-catalyzed Suzuki coupling. This method overcomes many of the drawbacks associated with the previously reported syntheses. The saponification of the methyl ester in valsartan was realized in a convenient and economical manner, which is more suitable for industrial production. Georg Thieme Verlag Stuttgart.
- Zhang, Chen,Zheng, Guojun,Fang, Lijing,Li, Yulin
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p. 475 - 477
(2007/10/03)
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- Catalyzed asymmetric aryl transfer reactions to aldehydes with boroxines as aryl source
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Asymmetric aryl transfer of triphenylboroxin to a set of aryl aldehydes has been carried out in the presence of chiral amino alcohols derived from (S)-proline with high enantioselectivity. Substituted phenyl boroxins were also used as aryl source in asymmetric arylation of benzaldehyde.
- Wu, Xiaoyu,Liu, Xinyuan,Zhao, Gang
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p. 2299 - 2305
(2007/10/03)
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- 14C-labeled and large-scale synthesis of the angiotensin-(1-7)-receptor agonist AVE 0991 by cross-coupling reactions.
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The synthesis of (14)C-labeled AVE 0991 ((14)()C-1a) and large-scale synthesis of AVE 0991 (1a) are described. In the key step of the synthesis, the C-C coupling reaction of the imidazole (2) and thiophene (3) building blocks was studied under Suzuki and Stille reaction conditions, respectively. Suzuki reaction gave only moderate yields, whereas the best results were obtained under Stille reaction conditions with up to 64% yield.
- Derdau, Volker,Oekonomopulos, Raymond,Schubert, Gerrit
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p. 5168 - 5173
(2007/10/03)
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- Formation of boroxine: Its stability and thermodynamic parameters in solution
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Condensation of three boronic acids proceeding at room temperature gave their corresponding boroxines; NMR spectral measurements revealed that the reaction was reversible at room temperature, that electron-donating groups supported the formation of boroxine, and that entropically driven forces promoted the formation of boroxine in solution.
- Tokunaga, Yuji,Ueno, Hiroki,Shimomura, Youji,Seo, Toshihiro
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p. 787 - 790
(2007/10/03)
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