- Direct bromodeboronation of arylboronic acids with CuBr2 in water
-
An efficient and practical method has been developed for the preparation of aryl bromides via the direct bromodeboronation of arylboronic acids with CuBr2 in water. This strategy provides several advantages, such as being ligand-free, base-free, high yielding, and functional group tolerant.
- Tang, Yan-Ling,Xia, Xian-Song,Gao, Jin-Chun,Li, Min-Xin,Mao, Ze-Wei
-
supporting information
(2021/01/05)
-
- ipso-Bromination/iodination of arylboronic acids: Poly(4-vinylpyridine)-Br2/I2 complexes as safe and efficient reagents
-
Poly(4-vinyl pyridine) supported bromine/iodine complexes were prepared and probed for ipso-bromination/iodination of arylboronic acids. These solid complexes with catalytic amount of additive are found to be safe and efficient reagent system for the ipso-bromination/iodination. The reaction occurs under mild conditions and tolerates various functional groups resulting in products with high selectivity and yields.
- Fu, Fang,Gurung, Laxman,Czaun, Miklos,Mathew, Thomas,Prakash, G.K. Surya
-
supporting information
(2019/08/26)
-
- Acceptorless Dehydrogenation of Hydrocarbons by Noble-Metal-Free Hybrid Catalyst System
-
A hybrid catalysis that comprises an acridinium photoredox catalyst, a thiophosphate organocatalyst, and a nickel catalyst-enabled acceptorless dehydrogenation of hydrocarbons is reported. The cationic nickel complex played a critical role in the reactivity. This is the first example of acceptorless dehydrogenation of hydrocarbons by base metal catalysis under mild reaction conditions of visible light irradiation at room temperature.
- Fuse, Hiromu,Kojima, Masahiro,Mitsunuma, Harunobu,Kanai, Motomu
-
supporting information
p. 2042 - 2045
(2018/04/16)
-
- Nickel-Catalyzed Deamidative Step-Down Reduction of Amides to Aromatic Hydrocarbons
-
To date, cleavage of the C-N bond in aromatic amides has been achieved in molecules with a distorted constitutional framework around the nitrogen atom. In this report, a nickel-catalyzed reduction of planar amides to the corresponding lower hydrocarbon homologue has been reported. This involves a one-pot reductive cleavage of the C-N bond followed by a tandem C-CO bond break in the presence of a hydride source. Substrate scope circumscribes deamidation examples which proceed via oxidative addition of nickel in the amide bonds of nontwisted amides. Mechanistic studies involving isolation and characterization of involved intermediates via different spectroscopic techniques reveal a deeper introspection into the plausible catalytic cycle for the methodology.
- Dey, Aniruddha,Sasmal, Sheuli,Seth, Kapileswar,Lahiri, Goutam Kumar,Maiti, Debabrata
-
p. 433 - 437
(2017/06/05)
-
- A mild and ligand-free Ni-catalyzed silylation via C-OMe cleavage
-
Metal-catalyzed transformations that forge carbon-heteroatom bonds are of central importance in organic synthesis. Despite the formidable potential of aryl methyl ethers as coupling partners, the scarcity of metal-catalyzed C-heteroatom bond formations via C-OMe cleavage is striking, with isolated precedents requiring specialized, yet expensive, ligands, high temperatures, and π-extended backbones. We report an unprecedented catalytic ipso-silylation of aryl methyl ethers under mild conditions and without recourse to external ligands. The method is distinguished by its wide scope, which includes the use of benzyl methyl ethers, vinyl methyl ethers, and unbiased anisóle derivatives, thus representing a significant step forward for designing new C-heteroatom bond formations via C-OMe scission. Applications of this transformation in orthogonal silylation techniques as well as in further derivatizations are also described. Preliminary mechanistic experiments suggest the intermediacy of Ni(0)-ate complexes, leaving some doubt that a canonical catalytic cycle consisting of an initial oxidative addition of the C-OMe bond to Ni(0) species comes into play.
- Zarate, Cayetana,Nakajima, Masaki,Martin, Ruben
-
p. 1191 - 1197
(2017/05/16)
-
- A mild Ni/Cu-catalyzed silylation via C -O cleavage
-
A Ni/Cu-catalyzed silylation of unactivated C-O electrophiles derived from phenols or benzyl alcohols is described. This transformation is characterized by its wide scope and mild conditions, providing a direct access to synthetically versatile silylated compounds. The protocol allows for the coupling of C(sp 2)-O and even C(sp3)-O bonds with similar efficiency.
- Zarate, Cayetana,Martin, Ruben
-
p. 2236 - 2239
(2014/03/21)
-
- Halodeboronation of organotrifluoroborates using tetrabutylammonium tribromide or cesium triiodide
-
Halodeboronation of organotrifluoroborates using commercially available tetrabutylammonium tribromide (TBATB) or cesium triiodide in aqueous medium is reported. The mild, transition metal-free method has proven to be tolerant of a wide range of functional groups. High regio- and chemoselectivity are observed. Two synthetic routes to (Z)-dibromoalkenes from alkynes, through stereodefined (Z)-2-bromoalkenyltrifluoroborates and (Z)-1,2-bis(boryl) alkenyltrifluoroborates, have been developed using the TBATB mediated bromodeboronation as the key step.
- Yao, Min-Liang,Kabalka, George W.,Blevins, David W.,Reddy, Marepally Srinivasa,Yong, Li
-
experimental part
p. 3738 - 3743
(2012/06/30)
-
- Ruthenium-catalyzed transformation of aryl and alkenyl triflates to halides
-
Aryl triflates were transformed to aryl bromides/iodides simply by treating them with LiBr/NaI and [Cp*Ru(MeCN)3]OTf. The ruthenium complex also catalyzed the transformation of alkenyl sulfonates and phosphates to alkenyl halides under mild conditions. Aryl and alkenyl triflates undergo oxidative addition to a ruthenium(II) complex to form η'1- arylruthenium and 1-ruthenacyclopropene intermediates, respectively, which are transformed to the corresponding halides.
- Imazaki, Yusuke,Shirakawa, Eiji,Ueno, Ryota,Hayashi, Tamio
-
supporting information
p. 14760 - 14763
(2012/11/07)
-
- An improved palladium-catalyzed conversion of aryl and vinyl triflates to bromides and chlorides
-
A facile Pd-catalyzed conversion of aryl and vinyl triflates to aryl and vinyl halides (bromides and chlorides) is described. This method allows convenient access to a variety of aryl, heteroaryl, and vinyl halides in good to excellent yields and with greatly simplified conditions relative to our previous report.
- Pan, Jun,Wang, Xinyan,Zhang, Yong,Buchwald, Stephen L.
-
supporting information; experimental part
p. 4974 - 4976
(2011/11/06)
-
- Chemoselective bromodeboronation of organotrifluoroborates using tetrabutylammonium tribromide: Application in (Z)-dibromoalkene syntheses
-
(Chemical Equation Presented) Tetrabutylammonlum trlbromlde (TBATB) has been found to be a unique bromodeboronatlon reagent for organotrlf luoroborates. When compared to previously reported bromodeboronatlon methods, the mild and metal-free reaction conditions tolerate a wider range of functional groups. High reglo- and chemoselectlvlty are observed In the presence of both unsaturated carbon-carbon bonds and aldehyde functional groups. An efficient synthetic route to (Z)-dlbromoalkenes from terminal alkynes has been developed using the TBATB-medlated bromodeboronatlon as a key step.
- Yao, Min-Liang,Reddy, Marepally Srinivasa,Li, Yong,Walfish, Ingrid,Blevins, David W.,Kabalka, George W.
-
supporting information; experimental part
p. 700 - 703
(2010/04/02)
-
- Ruthenium-catalyzed transformation of alkenyl triflates to alkenyl halides
-
In the presence of a ruthenium catalyst, alkenyl triflates were found to be transformed to the corresponding bromides, chlorides and iodides simply by treatment with a lithium halide (1.2 equiv.). The Royal Society of Chemistry 2009.
- Shirakawa, Eiji,Imazaki, Yusuke,Hayashi, Tamio
-
scheme or table
p. 5088 - 5090
(2009/12/08)
-
- Synthesis and photophysical processes of 9-bromo-10-naphthalen-2-yl-anthracene
-
A novel luminescent compound, 9-bromo-10-naphthalen-2-yl-anthracene (BNA) is synthesized by Suzuki Cross-coupling reaction of 9-bromo-anthracene and naphthalene-2-boronic acid. The structure is characterized by 1H NMR, IR and UV-vis spectroscopy. The photophysical processes of 9-bromo-10-naphthalen-2-yl-anthracene have been carefully investigated by UV-vis absorption and fluorescence spectra. The results show that the compound emits blue and blue-violet light. The emission spectra exhibit obvious solvent effect. With the difference in polarity of solvents, The emission spectra is not only slightly blue shift with the increase of the solvent polarity but also change on the intensity of fluorescence at room temperature .The light emitting can be quenched by electron donor, N,N-dimethylaniline (DMA). On adding gradually DMA into the solution of BNA, the emission intensities of fluorescence are gradually decreased. The quenching effect follows the Stern-Volmer equation.
- Guo, Zhiqiang,Jin, Shuo,Liu, Bo
-
p. 672 - 675
(2007/10/03)
-
- The stereochemical course of the generation and interception of a six-membered cyclic allene: 3δ2-1H-naphthalene (2,3-didehydro-1,2-dihydronaphthalene)
-
The bromofluorocarbene adduct rac-1 of indene, possessing the fluorine atom at the endo position, is a useful substrate for the generation of the isonaphthalene 4 by the Doering-Moore-Skattebol reaction. By resolution of rac-1, an enantiomerically pure precursor of a six-membered cyclic allene was obtained for the first time. The treatment of (+)- or (-)-1, dissolved in 2,5-dimethyl-, 2-tert-butyl-5-methyl-, or 2,5-bis-(tert-butyl)furan, with methyllithium gave rise to the [4+2] cycloadducts 6 of 4 to the furans. It was shown by means of HPLC on Chiralcel OD that the formation of 6 proceeded with about 40 % ee, and that this value was independent of the type and concentration of the furan, and the reaction temperature. The absolute configurations of the enantiomers 1, as well as those of the enantiomers 6, were determined by simulation of the CD spectra by quantum chemical methods and by the comparison of them with the experimental spectra. In the case of (+)-1, the reliability of this procedure was checked by X-ray crystal structure analysis. On the basis of these results, a model is proposed for the steric course of the reaction sequence, leading from a pure enantiomer 1 to the 70:30 mixtures of the product enantiomers 6. The use of indene as trapping reagent for 4 furnished the [2+2] cycloadduct 15. For the preparation of rac-15, the particularly simple one-pot procedure was employed, in which indene, tetra-bromomethane, and methyllithium were combined and in which the dibromocarbene adduct 2 of indene serves as precursor of 4. Compound 2 could not be isolated, but was characterised by low-temperature 1H NMR spectra. The conversion of (+)- or (-)-1 into 4 in the presence of indene afforded 15 only with a very low enantioselectivity. The constitutions and the relative configurations of 15 as well as the compounds 8 and 16, which resulted from thermolysis of the cycloadducts 6b and 15, respectively, were elucidated by X-ray crystal diffraction. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Christl, Manfred,Braun, Martin,Fischer, Hartmut,Groetsch, Stefan,Mueller, Germar,Leusser, Dirk,Deuerlein, Stephan,Stalke, Dietmar,Arnone, Mario,Engels, Bernd
-
p. 5045 - 5058
(2007/10/03)
-
- The conversion of phenols to the corresponding aryl halides under mild conditions
-
Mild, novel procedures have been developed for the syntheses of aryl halides from the corresponding phenols in modest to good yields via boronate ester intermediates.
- Thompson, Alicia L. S.,Kabalka, George W.,Akula, Murthy R.,Huffman, John W.
-
p. 547 - 550
(2007/10/03)
-
- Reductions of aryl perfluorosulfonates with dimethylamine·borane (Me2NH·BH3) catalyzed by Pd(0): An operationally simple, inexpensive, and general protocol
-
Treatment of aryl nonaflates or triflates in CH3CN in the presence of one equivalent of Me2NH·BH3 and K2CO3 leads via Pd(0) catalysis to high yields of reduced arenes.
- Lipshutz, Bruce H.,Buzard,Vivian, Randall W.
-
p. 6871 - 6874
(2007/10/03)
-
- Determination of the gas-phase acidities of halogen-substituted aromatic compounds using the silane-cleavage method
-
The gas-phase acidities of halogen-substituted aromatic compounds have been determined in a flowing afterglow-triple quadrupole apparatus with use of the silane cleavage method developed by DePuy and co-workers [C. H. DePuy, S. Gronert, S. E. Barlow, V. M. Bierbaum and R. Damrauer, J. Am. Chem. Sec., 111, 1968 (1989)]. In this method the relative yields of siloxide ion products produced in reactions of OH- with trimethylsilyl- or phenyidimethylsilyl-substituted aromatic compounds are correlated with the difference in gas-phase acidity of the accompanying neutral products. Acidities are reported for different ring-positions in fluoro-, chloro- and bromobenzene, chloro- and bromonaphthalene and benzyl chloride. Excellent precision is achieved in most cases, with assigned uncertainties less than 23 kcal/mol. Goad agreement is obtained between the acidities determined with use of two different types of silane precursor. Halogen-substitution increases the gas-phase acidities of benzene and naphthalene by similar amounts (13-14 kcal/mol). The effects on different ring-positions in benzene and naphthalene are shown to be primarily inductive in nature, falling-off by a consistent 2.5-3.5 kcal/mol per bond separating the acidic site from the haloges-bearing carbon in the chlorine and bromine-substituted systems. Larger effects are evident in the positional acidities of fluorobenzene. The meta and pava position acidities of halobenzenes are shown to be linearly correlated with the acidities of the corresponding meta and pava halophenols, haloanilines and halotoluenes.
- Wenthold,Squires
-
-
- THE INVENTION OF RADICAL REACTIONS. PART XVI. RADICAL DECARBOXYLATIVE BROMINATION AND IODINATION OF AROMATIC ACIDS
-
Thiohydroxamic esters of aromatic carboxylic acids undergo clean decarboxylative bromination or iodination on treatment with bromotrichloromethane, iodoform or diiodomethane in the presence of a radical initiator.
- Barton, Derek H.R.,Lacher, Brigitte,Zard, Samir Z.
-
p. 4321 - 4328
(2007/10/02)
-
- Acylation of naphthalenes
-
Naphthalene substituted in the 2- or β-position with an electron-donating substituent can be acylated with high regioselectivity in the 6-position by using an acylating agent in substantially anhydrous hydrogen fluoride which functions both as catalyst and solvent.
- -
-
-
- A Computerised Least Square Method for Determination of Stability Constants of 1:1 Molecular Complexes and Chemical Shift of Pure Complexes from Nuclear Magnetic Resonance Data
-
A computerised method utilising nuclear magnetic resonance data has been developed for the determination of stability constants of 1:1 molecular complexes.It is based on the principle of least squares in which the coefficients are adjusted under a constraint with the help of Lagrange's method of undetermined multipliers.The method utilises the complete expression for equilibrium constant and is mathematically rigorous, straightforward, non-iterative and requires very little computer time.
- Seal, B. K.,Mukherjee, A. K.
-
p. 413 - 415
(2007/10/02)
-
- RADICAL DECARBOXYLATIVE BROMINATION OF AROMATIC ACIDS
-
Thiohydroxamic esters (mixed anhydrides) of aromatic and α,β-unsaturated carboxylic acids undergo clean decarboxylative bromination on treatment with bromotrichloromethane in the presence of a radical initiator.
- Barton, Derek H.R.,Lacher, Brigitte,Zard, Samir Z.
-
p. 5939 - 5942
(2007/10/02)
-
- Evidence for the Intermediacy of the Aryl Radical in the Sandmeyer Reaction
-
The competition between bromodediazoniation and chlorodediazoniation is exploited as a test of the occurrence of an aryl radical in the Sandmeyer reaction pathway.The use of five reducing agents, covering a wide range of redox ability, is shown not to influence the experimental kBr/kCl values.The intermediacy of a common species is consequently inferred and supported by independent generation of the phenyl radical by decomposition of benzoyl peroxide.Considerations on the rates of the ligand transfer processes are put forward.
- Galli, Carlo
-
p. 1139 - 1142
(2007/10/02)
-
