- Arynes and Their Precursors from Arylboronic Acids via Catalytic C-H Silylation
-
A new, operationally simple approach is presented to access arynes and their fluoride-activated precursors based on Ru-catalyzed C-H silylation of arylboronates. Chromatographic purification may be deferred until after aryne capture, rendering the arylboronates de facto precursors. Access to various new arynes and their derivatives is demonstrated, including, for the first time, those based on a 2,3-carbazolyne and 2,3-fluorenyne core, which pave the way for novel derivatizations of motifs relevant to materials chemistry.
- Devaraj, Karthik,Ingner, Fredric J.L.,Sollert, Carina,Gates, Paul J.,Orthaber, Andreas,Pilarski, Lukasz T.
-
p. 5863 - 5871
(2019/04/16)
-
- Microwave-induced covalent functionalization of few-layer graphene with arynes under solvent-free conditions
-
A non-conventional modification of exfoliated few-layer graphene (FLG) with different arynes under microwave (MW) irradiation and solvent-free conditions is reported. The described approach allows reaching fast, efficient and mild covalent functionalization of FLG.
- Sulleiro,Quiroga,Pe?a,Pérez,Guitián,Criado,Prato
-
supporting information
p. 2086 - 2089
(2018/03/06)
-
- Reactions of an Isolable Dialkylstannylene with Propynoates and Benzyne
-
The reactions of stable monomeric dialkylstannylene 1 with methyl and ethyl propynoates give the corresponding 1:2 adducts, alkenyl(alkynyl)stannane 2 and 3 in high yields, while 1 does not react with parent acetylene or common mono- and disubstituted acetylenes such as phenylacetylene, trimethylsilylacetylene, diethyl 2-butynedioate, etc. Notably, 2 and 3 have the Z-configuration of the alkenyl moieties, in contrast to similar adducts obtained by the known reactions of silylenes with terminal acetylenes. It is suggested that the formation of a carbonyl oxygen-coordinate cyclic zwitterion as a key intermediate is essential for the reactions. Stannylene 1 adds to in situ generated benzyne, forming a 1:1 adduct having a unique 3-stanna-1-silaindane ring system.
- Xu, Jian,Xiao, Xu-Qiong,Yan, Chenting,Li, Zhifang,Lu, Qiong,Yang, Qian,Lai, Guoqiao,Kira, Mitsuo
-
p. 2399 - 2405
(2018/08/21)
-
- Synthesis of Fused Polycyclic 1,4-Benzodiazepines via Metal-Free Cascade [5 + 2]/[2 + 2] Cycloadditions
-
A metal-catalyst-free, mild, and efficient synthetic protocol for polycyclic 1,4-benzodiazepines via cascade [5 + 2]/[2 + 2] cycloadditions between pyridinium zwitterions and arynes is reported. Mechanistic experiments revealed that pyridinium zwitterions act as 1,5-dipoles in [5 + 2] cycloadditions with arynes for the construction of 1,4-benzodiazepines, which further undergo [2 + 2] cycloaddition resulting in the one-pot formation of one C-N bond and three C-C bonds.
- Shin, Jinhwan,Lee, Jiyoun,Ko, Donguk,De, Nirupam,Yoo, Eun Jeong
-
p. 2901 - 2904
(2017/06/07)
-
- ROOM TEMPERATURE POLYMER CROSSLINKING USING 1-FUNCTIONALIZED BENZOCYCLOBUTENE
-
Specific benzocyclobutenes serve as intramolecular or intermolecular or both intramolecular or intermolecular crosslinkers. The benzocyclobutenes can be incorporated into polymers post polymerization or can be provided as monomers that participate in homo
- -
-
-
- Lewis acid triggered reactivity of a lewis base stabilized scandium-terminal imido complex: C-H bond activation, cycloaddition, and dehydrofluorination
-
A stable scandium-terminal imido complex is activated by borane to form an unsaturated terminal imido complex by removing the coordinated Lewis base, 4-(dimethylamino)pyridine, from the metal center. The ensuing terminal imido intermediate can exist as a
- Chu, Jiaxiang,Han, Xianghao,Kefalidis, Christos E.,Zhou, Jiliang,Maron, Laurent,Leng, Xuebing,Chen, Yaofeng
-
supporting information
p. 10894 - 10897
(2014/08/18)
-
- Temporary intramolecular generation of pyridine carbenes in metal-free three-component C - H bond functionalisation/aryl-transfer reactions
-
Nucleophilic addition of pyridines to benzyne generates zwitterionic adducts that evolve by a rapid intramolecular proton shift to produce the corresponding pyridine carbenes, N-phenyl pyrid-2-ylidenes. In the presence of electrophilic ketones (isatin derivatives), the pyridylidenes can further react by an original bis-arylation reaction of the carbonyl compounds involving a formal pyridine C - H bond functionalisation. The overall transformation is an unprecedented three-component reaction featuring a carbene intermediate. The mechanism of this transformation was examined in detail by using both experimental and theoretical approaches. It was found that the generation of N-phenyl pyrid-2-ylidene from pyridine and benzyne is energetically favoured, and that the corresponding carbene dimer can also form easily. Under the three-component reaction conditions, the pyridylidene preferentially adds to the ketone group of the isatin derivative to produce a zwitterionic adduct amenable to an intramolecular aryl transfer reaction by a concerted nucleophilic aromatic substitution. This peculiar reactivity for a carbene was compared to possibly competitive known reactions of stable carbenes with carbonyl compounds, and the reaction was found to be under thermodynamic control. The reported method of generation of N-phenyl pyrid-2-ylidenes and their reactivity with carbonyl compounds unlock new perspectives in organic synthesis. Carbene reactivity: Pyridine reacts with benzyne by a nucleophilic addition/ intramolecular proton shift sequence to generate N-phenyl pyrid-2-ylidenes (see scheme). These unusual carbenes react with isatin derivatives in an original three-component bis-arylation reaction involving a formal pyridine C - H bond functionalisation. The mechanism of the reaction has been investigated experimentally and theoretically.
- Nawaz, Faisal,Mohanan, Kishor,Charles, Laurence,Rajzmann, Michel,Bonne, Damien,Chuzel, Olivier,Rodriguez, Jean,Coquerel, Yoann
-
p. 17578 - 17583
(2014/01/06)
-
- Pitfalls in the photoelectron spectroscopic investigations of benzyne. photoelectron spectrum of cyclopentadienylideneketene
-
The 9.24 eV ionization energy often quoted in photoelectron spectroscopic investigations of benzyne is not due to benzyne 1 but to benzene, C 6H6. The 8.9 eV ionization is not due to benzyne either but to cyclopentadienylideneketene 12 when a 10.2 eV band is also present, or to biphenylene 5 when a 7.6 eV band is simultaneously present. Cyclopentadienylideneketene 12 has been generated by flash vacuum thermolysis of four different precursors, which permit a linking of infrared, mass, and photoelectron spectroscopic observations.
- Chrostowska, Anna,Pfister-Guillouzo, Genevieve,Gracian, Franoise,Wentrup, Curt
-
experimental part
p. 1084 - 1090
(2011/04/15)
-
- Mass spectrometry of benzyne and cyclopentadienylideneketene
-
The formation of cyclopentadienylideneketene 2 and benzyne 1 in flash vacuum thermolysis reactions is investigated by on-line mass spectrometry. Compounds 13, 14, and 15 all afford ketene 2, which decomposes to benzyne and CO in the high-temperature regime. Cyclopentadienylideneketene 2 is stable on the microsecond time-scale of neutralization-reionization experiments. Collisional activation mass spectrometry of m/z 76 from 14, 15, and 5 indicates that the C6H4·+ ions most likely undergo ring opening in the mass spectrometer.
- Monsandl, Thomas,MacFarlane, Graham,Flammang, Robert,Wentrup, Curt
-
experimental part
p. 1076 - 1083
(2011/04/15)
-
- The Reaction of Acetic Acid 2-Selenoxo-2H-pyridin-1-yl Esters with Benzynes: A Convenient Route to Benzo[b]seleno[2,3-b]pyridines
-
Benzyne and its 3,4,5,6-tetraphenyl, 3- and 4-methyl, 3-methoxy and 4,5-difluoro derivatives react with acetic acid 2-selenoxo-2H-pyridin-1-yl esters 4a-e to give benzo[b]seleno[2,3-b]pyridines 10-15 in modest yields. The benzynes were generated by one or more of the following methods: diazotization of anthranilic acids 5a-g with isoamyl nitrate; mild thermal decomposition of 2-diazoniobenzenecarboxylate hydrochlorides 6a-d; treatment of (phenyl)[o-(trimethylsilyl)phenyl]iodonium triflate (7) with tetrabutylammonium fluoride; and treatment of 2-trimethylsilylphenyl triflates 8a-c with cesium fluoride. In all the reactions, the corresponding 2-(methylselenenyl)pyridines 16a-d were also obtained suggesting that these reactions may involve selenium addition to benzyne via a SET (single electron transfer).
- Rao, U. Narasimha,Sathunuru, Ramadas,Maguire, John A.,Biehl, Ed
-
-
- Polarization Spectroscopy and ab Initio Study of Photooriented Matrix-Isolated Isotopomers of Phthalic Anhydride. Assignment of the Infrared Absorption Spectrum
-
In this paper we provide an assignment of symmetries for all transitions observed in the infrared spectrum of phthalic anhydride (1a), based on data determined from polarization studies of photooriented 1a.Photoselection, using two electronic transitions in phthalic anhydride 1a, at 34083 and 40650 cm-1 and of A1 and B2 symmetry, respectively, produced two differently oriented uniaxial samples of the anhydride immobilized in neon and other noble-gas matrices.Subsequent polarization measurements in the infrared region, combined with polarized Raman data, allowed a complete determination of transition moment directions for all observed fundametal vibrations.To facilitate definitive spectral assignments, we studied three isotopomers of 1a: 1,2-(13)C labeled phthalic anhydride (1b), the perdeuterated phthalic anhydride (1c), and the α-13C-labeled compound (1d).Absolute infrared absorption intensities were determined for all observed transitions utilizing absolute infrared absorption intensities of CO and CO2, formed in equimolar amounts with o-benzyne (2) in phototransformations of 1.Interpretation of the experimental results and the final assignments were aided by quantum mechanical modeling at the SCF/6-31G** level.
- Biernacki, Peter R.,Kaszynski, Piotr,Hess, B. Andes,Thulstrup, Erik W.,Radziszewski, Juliusz G.
-
p. 6309 - 6316
(2007/10/02)
-
- Infrared spectrum of o-benzyne: Experiment and theory
-
The complete set of vibrational frequencies and absolute infrared intensities has been determined for o-benzyne and two of its isotopomers: C6D4 and 1,2-13C2C4H4. In addition, for the majority of the transitions symmetries were assigned from infrared linear dichroism of the matrix-isolated samples, photooriented with polarized light during several photochemical transformations. Thermal relaxation of the high static pressure created by the initial photofragmentation causes dramatic changes of the fine site structure of each band of o-benzyne and results in a single-site infrared absorption spectra. A high-resolution, single-site vibrational spectrum was also obtained independently from laser hole-burning experiments. Band-shape analysis in different inert gas matrices (Ne, Ar, Xe, N2, and CO) greatly facilitates the correlation of isotopomer bands with those of unlabeled o-benzyne. The triple bond stretching vibration appears at 1846 cm-1 in a Ne matrix, with an experimental absolute intensity of 2.0 ± 0.4 km/mol in the unlabeled o-benzyne and is polarized along the symmetry axis. It is red-shifted by 2 cm-1 in the perdeutero-o-benzyne and by 53 cm-1 in the doubly 13C-labeled compound, in very good agreement with our theoretical prediction (MP2/6-31G**) and previous gas-phase data for o-benzyne.
- Radziszewski, Juliusz G.,Hess Jr., B. Andes,Zahradnik, Rudolf
-
-
- Gas-Phase Chemistry of the Dimethyaluminum Oxide Ion and Related Aluminum Oxide Ions: Comparison of Reactivity with Siloxide Ions
-
The anion [CH3)2Alo]- (1) has prepared In a flowing afterglow selected ion flow tube (FA-SIFT) by ion selection from the reaction mixture of trimethylaluminum dimer and hydroxide. This unusual ion is quite reactife and has extensively studied. It with halogen-containing compounds of several types, including fluorobenzene, chlorobenzene, bromofluorobenzene, acetyl chloride, and HF, to give {(CHj^AKOHJX] , where X = F, Cl, and Br. Its chemistry with hexafteorabenzene and silicon tetrafluoride has also detailed as have a number of reactions with carboxylic adds, esters, anhydrides, sulfur-containing neutrals, alcohols, water, and ammonia. The dominant reaction pattern of 1 involves six-centered processes which require a relatively acidic hydrogen and a lone pair donor atom in the neutral reactant. In these reactions, ion 1 abstracts a proton as the lone pair atom to aluminum, often with concomitant extrusion of a small, neutral molecule. We have compared the reactifity of 1 with that of [(CH3)3SiO]- and briefly examined other aluminum oiide ions. The kinetics of several reactions as well the thermochemical relationships among some of these ions have studied, Acidity studies coupled with thermochemical analysis establish that the conjugate acid of [A1O]~ is A1OH, not HA1O. Computational studies out to the reaction of trimethylaluminum and hydroxide, and the acidities and of A1OH and HA1O.
- Damrauer, Robert,Krempp, Mich?ele,Micheal,Gordon
-
p. 2393 - 2400
(2007/10/02)
-
- THE RADICAL COUPLING MECHANISM IN THE DIAZO COUPLING REACTION. MIGRATION VS. DECOMPOSITION OF PHENYLAZO RADICAL GENERATED FROM PHENYLAZO 1-NAPHTHYL ETHER IN THE SOLVENT CAGE
-
The thermal reaction of phenylazo 1-naphthyl ether generates a pair of phenylazo and naphthoxy radicals in the solvent cage, in which these radicals couple together at the aromatic carbon to give 4-phenylazo-1-naphthol and 2-phenylazo-1-naphthol.
- Tezuka, Takahiro,Tanikawa, Hiroharu,Sasaki, Katsunori,Tajima, Harumi
-
p. 1811 - 1814
(2007/10/02)
-
- Synthesis and Reactions of 1,2-Fused 3-Cyanoindolizines
-
With the intention that annulation of carbo- or heteroaromatic rings at the 1,2-positions can activate 3-cyanoindolizines as 1,3-dipolar species, 6-cyanobenzindolizines, pyridazinoindolizines and 5-cyano-1,3-diphenylthiophenoindolizine we
- Matsumoto, Kiyoshi,Uchida, Takane,Aoyama, Kinuyo,Nishikawa, Masahiko,Kuroda, Takeshi,Okamoto, Tadashi
-
p. 1793 - 1801
(2007/10/02)
-
- DETECTION BY INFRARED SPECTROSCOPY OF BENZYNE FORMED BY FLASH VACUUM PYROLYSIS AND TRAPPED IN AN ARGON MATRIX
-
Benzyne has been detected in the argon matrices obtained from pyrolyses of isobenzofuran-1,3-dione (1), 2,3-benzodioxin-1,4-dione (2), benzocyclobutenedione (3), 2,2-dimethyl-5-(octahydro-1',2',4'-methano-3'H-cyclobutapentalen-3'-ylidene)-1,3-dioxan-4,6-dione (8) and 5,5'-(pentacyclo2,6.04,10.05,8>decane-3'',9''-diylidene)bis(2,2-dimethyl-1,3-dioxan-4,6-dione) (9).At both 650 deg C and 700 deg C compound (3) yields only benzyne while (8) yields ketenes and benzyne.It is suggested that compounds (1), (2) and (3) undergo concerted fragmentation to benzyne while (8) and (9) give ketene intermediates which fragment to benzyne.
- Brown, Roger F. C.,Browne, Neil R.,Coulston, Karen J.,Danen, Louisa B.
-
p. 1075 - 1078
(2007/10/02)
-
- Novel Benzyne Additions to the 1,2,5-Thiadiazole and 1,2,5-Selenadiazole Ring Systems
-
Novel modes of benzyne addition to 3,4-dimethyl-1,2,5-thiadiazole and 3,4-dimethyl-1,2,5-selenadiazole afford methyl derivatives of three heterocyclic systems: quinoxaline, 1,2-benzisothiazole, and 1,3-benzoselenazole respectively.
- Bryce, Martin R.,Hanson, Peter,Vernon, John M.
-
p. 299 - 300
(2007/10/02)
-
- Small rings, 36. Attempts to Synthesize Tetramethyltetrahedrane from Alicyclic Precursors
-
Synthesis as well as the thermal and photochemical behaviour of compounds with ring skeletons 1 and 3 are described.Whereas the former are accessible by standard procedures the approach to the bicyclobutane derivatives is based on the isomerization of diester 1b into valence isomer 3b which can be achieved in good yield by SiO2 or Al2O3.There are only minor differences in the cleavage of the pairs 1/3 provoked by heating or photochemical excitation.This is even true for irradiations in argon at 10 K.Under those conditions anhydrides 1a and 3a form the samecharge transfer complex 28a between tetramethylcyclobutadiene and phthalic anhydride.A direct detection of tetramethyltetrahedrane using these means is not possible.
- Maier, Guenther,Mayer, Wolfram,Freitag, Hans-Albrecht,Reisenauer, Hans Peter,Askani, Rainer
-
p. 3935 - 3958
(2007/10/02)
-
- Substituted 9,10-dihydroanthracen-9,10-imines
-
Substituted 9,10-dihydroanthracen-9,10-imines are disclosed to be minor tranquilizers, anticonvulsnts, muscle relaxants, and to be useful in the treatment of extrapyramidal disorders such as Parkinson's disease; also disclosed are processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; and methods of treatment comprising administering such compounds and compositions.
- -
-
-