- Reductive electrophilic substitution of diarylmethyl methyl ethers: Synthetic applications
-
The reductive cleavage of diarylmethyl methyl ethers with Li metal in THF led to quantitative formation of the corresponding diarylmethyl anions. Quenching with electrophiles afforded substituted diarylmethanes in good to excellent yields.
- Azzena,Melloni,Fenude,Fina,Marchetti,Sechi
-
-
Read Online
- Niobium(V) pentachloride: an efficient catalyst for C-, N-, O-, and S-nucleophilic substitution reactions of benzylic alcohols
-
Benzylic alcohols undergo easy C-, N-, O-, and S- centered nucleophilic substitution reactions with a catalytic amount of NbCl5.
- Yadav,Bhunia, Dinesh C.,Vamshi Krishna,Srihari
-
-
Read Online
- Photoinduced Electron Transfer to a Carbenium Ion
-
Irradiation (λ>430 nm) of the cation obtained by protonation of 1,1-di-p-anisylethylene (1) in the presence of excess 1 in benzene-trifluoroacetic acid solution results in electron transfer from the nautral ethylene and the formation of the corresponding
- Al-Ekabi, H.,Kawata, H.,Mayo, P. de
-
-
Read Online
- Organometallic Phase Transfer Catalysis under Acidic Conditions. Cobalt Carbonyl Induced Hydrogenation of Activated Olefins
-
Diarylethylenes and 9,9'-bifluorenylidene are hydrogenated, in excellent yields, on treatment with cobalt carbonyl or bis(tri-n-butylphosphine)dicobalt hexacarbonyl, benzene, 48-50percent aqueous tetrafluoroboric acid, and sodium 4-dodecylbenzenesulphonate.
- Alper, Howard,Heveling, Josef
-
-
Read Online
- Direct electrochemical reduction of 4,4-(2,2,2-trichloroethane-1,1-diyl)bis(methoxybenzene) (methoxychlor) at carbon and silver cathodes in dimethylformamide
-
Cyclic voltammetry and controlled-potential (bulk) electrolysis have been employed to investigate the electrochemical reduction of 4,4-(2,2,2-trichloroethane-1,1-diyl)bis(methoxybenzene), commonly known as the pesticide methoxychlor, at glassy carbon and silver cathodes in dimethylformamide (DMF) containing 0.050 M tetra-n-butylammonium tetrafluoroborate (TBABF4). Reduction of methoxychlor at both glassy carbon and silver shows four voltammetric peaks, the first three of which are associated with cleavage of carbon–chlorine bonds; the fourth peak is assigned to reduction of 4,4-(ethene-1,1-diyl)bis(methoxybenzene). Bulk electrolyses of methoxychlor at reticulated vitreous carbon and silver mesh cathodes at potentials corresponding to each of the first three voltammetric peaks were conducted; coulometric n values and product distributions (determined by means of GC and GC–MS techniques) depend on potential. In particular, two completely dechlorinated products, namely 4,4-(ethane-1,1-diyl)bis(methoxybenzene) and 4,4-(ethene-1,1-diyl)bis(methoxybenzene) have been identified and quantitated. A mechanistic scheme is proposed to account for the formation of the various products.
- McGuire, Caitlyn M.,Peters, Dennis G.
-
-
Read Online
- Indium Tribromide-Catalysed Transfer-Hydrogenation: Expanding the Scope of the Hydrogenation and of the Regiodivergent DH or HD Addition to Alkenes
-
The transfer-hydrogenation as well as the regioselective and regiodivergent addition of H?D from regiospecific deuterated dihydroaromatic compounds to a variety of 1,1-di- and trisubstituted alkenes was realised with InBr3 in dichloro(m)ethane. In comparison with the previously reported BF3?Et2O-catalysed process, electron-deficient aryl-substituents can be applied reliably and thereby several restrictions could be lifted, and new types of substrates could be transformed successfully in hydrodeuterogenation as well as deuterohydrogenation transfer-hydrogenation reactions.
- Li, Luomo,Hilt, Gerhard
-
supporting information
p. 11221 - 11225
(2021/06/25)
-
- Site-Specific Oxidation of (sp3)C-C(sp3)/H Bonds by NaNO2/HCl
-
A site-specific oxidation of (sp3)C-C(sp3) and (sp3)C-H bonds in aryl alkanes by the use of NaNO2/HCl was explored. The method is chemical-oxidant-free, transition-metal-free, uses water as the solvent, and proceeds under mild conditions, making it valuable and attractive to synthetic organic chemistry.
- Zhao, Jianyou,Shen, Tong,Sun, Zhihui,Wang, Nengyong,Yang, Le,Wu, Jintao,You, Huichao,Liu, Zhong-Quan
-
supporting information
p. 4057 - 4061
(2021/05/26)
-
- Regiodivergent DH or HD Addition to Alkenes: Deuterohydrogenation versus Hydrodeuterogenation
-
The regioselective and regiodivergent addition of H-D to a variety of 1,1-diarylalkenes was realized utilizing selectively deuterated dihydroaromatic compounds, which were generated by cobalt catalysis. The reaction was initiated by catalytic amounts of B
- Hilt, Gerhard,Li, Luomo
-
supporting information
(2020/03/03)
-
- Electrochemical Hydrogenation with Gaseous Ammonia
-
As a carbon-free and sustainable fuel, ammonia serves as high-energy-density hydrogen-storage material. It is important to develop new reactions able to utilize ammonia as a hydrogen source directly. Herein, we report an electrochemical hydrogenation of alkenes, alkynes, and ketones using ammonia as the hydrogen source and carbon electrodes. A variety of heterocycles and functional groups, including for example sulfide, benzyl, benzyl carbamate, and allyl carbamate were well tolerated. Fast stepwise electron transfer and proton transfer processes were proposed to account for the transformation.
- Li, Jin,He, Lingfeng,Liu, Xu,Cheng, Xu,Li, Guigen
-
supporting information
p. 1759 - 1763
(2019/01/16)
-
- Catalytic protodeboronation of pinacol boronic esters: Formal anti-Markovnikov hydromethylation of alkenes
-
Pinacol boronic esters are highly valuable building blocks in organic synthesis. In contrast to the many protocols available on the functionalizing deboronation of alkyl boronic esters, protodeboronation is not well developed. Herein we report catalytic protodeboronation of 1°, 2° and 3° alkyl boronic esters utilizing a radical approach. Paired with a Matteson-CH2-homologation, our protocol allows for formal anti-Markovnikov alkene hydromethylation, a valuable but unknown transformation. The hydromethylation sequence was applied to methoxy protected (-)-Δ8-THC and cholesterol. The protodeboronation was further used in the formal total synthesis of δ-(R)-coniceine and indolizidine 209B.
- Clausen, Florian,Kischkewitz, Marvin,Bergander, Klaus,Studer, Armido
-
p. 6210 - 6214
(2019/06/27)
-
- Cyclohexa-1,3-diene-based dihydrogen and hydrosilane surrogates in B(C6F5)3-catalysed transfer processes
-
The cyclohexa-1,3-diene motif is introduced as an equally effective alternative to the cyclohexa-1,4-diene platform in B(C6F5)3-catalysed transfer processes. The transfer hydrogenation of alkenes is realised with α-terpinene and the related transfer hydrosilylation is achieved with 5-trimethylsilyl-substituted cyclohexa-1,3-diene. Both yields and substrate scope are comparable with the prior systems.
- Yuan, Weiming,Orecchia, Patrizio,Oestreich, Martin
-
supporting information
p. 10390 - 10393
(2017/09/25)
-
- Mild and regioselective benzylic C-H functionalization: Ni-catalyzed reductive arylation of remote and proximal olefins
-
The synergistic combination of NiH-catalyzed alkene isomerization with nickel-catalyzed cross-coupling has yielded a general protocol for the synthesis of a wide range of structurally diverse 1,1-diarylalkanes in excellent yields and high regioselectivities from readily accessible olefin starting materials. Furthermore, the practicality and synthetic flexibility of this approach is highlighted by the successful employment of isomeric mixtures of olefins for regioconvergent arylation.
- He, Yuli,Cai, Yalei,Zhu, Shaolin
-
supporting information
p. 1061 - 1064
(2017/05/15)
-
- Nucleophilicity of Alkyl Zirconocene and Titanocene Precatalysts, and Kinetics of Activation by Carbenium Ions and by B(C6F5)3
-
Kinetics of activation of methyl and benzyl metallocene precatalysts by benzhydrylium ions, tritylium ions, and triarylborane B(C6F5)3were measured spectrophotometrically. The rate constants correlate linearly with the electrophilicity parameter E of the benzhydrylium and tritylium ions employed, allowing us to determine the σ-nucleophilicities of the metal–carbon bond of several zirconocenes and titanocenes. Bridging, substitution, metal, and ligand effects on the rates of metal–alkyl bond cleavage (M=Zr, Ti) were studied and structure–reactivity correlations were used to predict the kinetics of generation of metallocenium ions pairs, which are active catalysts in polymerization reactions and are highly electrophilic Lewis acids in frustrated Lewis pair catalysis.
- Berionni, Guillaume,Kurouchi, Hiroaki,Eisenburger, Lucien,Mayr, Herbert
-
supporting information
p. 11196 - 11200
(2016/08/03)
-
- Cationic Iron(III) porphyrin catalyzed dehydrative friedel-crafts reaction of alcohols with arenes
-
Alcohols react with arenes in the presence of cationic iron(III) porphyrin catalyst. The reaction involves the formation of the C-C bond via dehydration, which is formal Lewis acid catalyzed Friedel-Crafts reaction. Georg Thieme Verlag Stuttgart, New York.
- Teranishi, Satoru,Kurahashi, Takuya,Matsubara, Seijiro
-
supporting information
p. 2148 - 2152
(2013/10/21)
-
- Development of a large scale asymmetric synthesis of the glucocorticoid agonist BI 653048 BS H3PO4
-
The development of a large scale synthesis of the glucocorticoid agonist BI 653048 BS H3PO4 (1·H3PO4) is presented. A key trifluoromethyl ketone intermediate 22 containing an N-(4-methoxyphenyl)ethyl amide was prepared by an enolization/bromine-magnesium exchange/electrophile trapping reaction. A nonselective propargylation of trifluoromethyl ketone 22 gave the desired diastereomer in 32% yield and with dr = 98:2 from a 1:1 diastereomeric mixture after crystallization. Subsequently, an asymmetric propargylation was developed which provided the desired diastereomer in 4:1 diastereoselectivity and 75% yield with dr = 99:1 after crystallization. The azaindole moiety was efficiently installed by a one-pot cross coupling/indolization reaction. An efficient deprotection of the 4-methoxyphenethyl group was developed using H3PO4/anisole to produce the anisole solvate of the API in high yield and purity. The final form, a phosphoric acid cocrystal, was produced in high yield and purity and with consistent control of particle size.
- Reeves, Jonathan T.,Fandrick, Daniel R.,Tan, Zhulin,Song, Jinhua J.,Rodriguez, Sonia,Qu, Bo,Kim, Soojin,Niemeier, Oliver,Li, Zhibin,Byrne, Denis,Campbell, Scot,Chitroda, Ashish,Decroos, Phil,Fachinger, Thomas,Fuchs, Victor,Gonnella, Nina C.,Grinberg, Nelu,Haddad, Nizar,Jaeger, Burkhard,Lee, Heewon,Lorenz, Jon C.,Ma, Shengli,Narayanan, Bikshandarkoil A.,Nummy, Larry J.,Premasiri, Ajith,Roschangar, Frank,Sarvestani, Max,Shen, Sherry,Spinelli, Earl,Sun, Xiufeng,Varsolona, Richard J.,Yee, Nathan,Brenner, Michael,Senanayake, Chris H.
-
p. 3616 - 3635
(2013/06/04)
-
- Carbon-based leaving group in substitution reactions: Functionalization of sp3-hybridized quaternary and tertiary benzylic carbon centers
-
Lewis acid promoted substitution reactions employing Meldrum's acid and 5-methyl Meldrum's acid as carbon-based leaving groups are described which transform unstrained quaternary and tertiary benzylic Csp 3-Csp3 bonds into Csp3-X bonds (X = C, H, N). Importantly, this reaction has a broad scope in terms of both suitable substrates and nucleophiles with good to excellent yields obtained (typically >90%).
- Mahoney, Stuart J.,Lou, Tiantong,Bondarenko, Ganna,Fillion, Eric
-
p. 3474 - 3477
(2012/09/05)
-
- Feeding the Heck reaction with alcohol: One-pot synthesis of stilbenes from aryl alcohols and bromides
-
Aryl alcohols are employed as feedstock for the Heck reaction. Keggin-type heteropolyacids catalyse the selective dehydration of the alcohols to styrenes, which, in one-pot, undergo palladium-catalysed Heck arylation with aryl bromides, affording broadly functionalised stilbenes. The choice of solvent is critical for the cascade dehydration-Heck reaction, with electron-rich aryl alcohols preferring a basic medium while electron-deficient ones demanding solvents of lower basicity. Copyright
- Colbon, Paul,Barnard, Jonathan H.,Purdie, Mark,Mulholland, Keith,Kozhevnikov, Ivan,Xiao, Jianliang
-
supporting information; scheme or table
p. 1395 - 1400
(2012/07/03)
-
- Iodine-catalyzed nucleophilic substitution reactions of benzylic alcohols
-
Molecular iodine efficiently catalyzes the direct nucleophilic substitution of the hydroxy group of benzylic alcohols with carbon and oxygen nucleophiles. Georg Thieme Verlag Stuttgart.
- Srihari, Pabbaraja,Bhunia, Dinesh C.,Sreedhar, Pamu,Yadav, Jhillu S.
-
experimental part
p. 1045 - 1049
(2009/04/04)
-
- Br?nsted-acid-catalyzed coupling of electron-rich arenes with substituted allylic and secondary benzylic alcohols
-
p-Toluenesulfonic acid and triflic acid catalyze efficiently the coupling of electron-rich arenes with allylic and benzylic alcohols. Reactions are conducted under mild conditions, in air, and in the absence of solvent.
- Le Bras, Jean,Muzart, Jacques
-
p. 7942 - 7948
(2008/02/08)
-
- Zeolite-Promoted Oxidations of 1,1-Diarylethylenes
-
(Equation Presented) The intrazeolite photooxygenations of four diarylethylenes have been examined. Several intermediates, including an epoxide, have been identified by comparison to independently synthesized samples. Aldehyde intermediates were shown to undergo intrazeolite Norrish type I cleavages in competition with a novel new photooxygenation/autoxidation reaction.
- Clennan, Edward L.,Pan, Gui-Ian
-
p. 4979 - 4982
(2007/10/03)
-
- Activation conditions play a key role in the activity of zeolite CaY: NMR and product studies of Bronsted acidity
-
CaY, activated under different conditions, was characterized with 1H, 31P, and 1H/27A] double resonance MAS NMR. The 1H MAS NMR spectra of CaY, calcined in an oven at 500 °C, shows resonances from H2O (bound to Ca2+ and the zeolite framework), CaOH+, aluminum hydroxides, silanols, and Bronsted acid sites. No evidence for Lewis acidity is observed on adsorption of trimethylphosphine, and an estimate of ≈16 Bronsted acid sites per unit cell is obtained for this sample. CaY activated in an oven at higher temperatures contains less water, but all the other species are still present. In contrast, CaY activated by slow ramping of the temperature under vacuum to 500 or 600 °C shows a much lower concentration of Bronsted acid sites (1/unit cell). Again, no evidence for Lewis acidity was observed. These NMR results have been utilized to understand the very different product distributions that are observed for reactions of 1,1- and 1,2-diarylethylenes in zeolite CaY activated in an oven (in air) and under vacuum. Samples with high concentrations of Bronsted acid sites react stoichiometrically with these sites, yielding diarylalkanes. At low concentrations, the Bronsted acid sites can act catalytically resulting in isomerization reactions.
- Kao, Hsien-Ming,Grey, Clare P.,Pitchumani, Kasi,Lakshminarasimhan,Ramamurthy
-
p. 5627 - 5638
(2007/10/03)
-
- Hole transfer promoted hydrogenation: One-electron oxidation as a strategy for selective reduction of π-bonds
-
One-electron oxidation is developed as a strategy for selective and efficient reduction of relatively ionizable functionalities, including conjugated dienes, styrenes, vinyl sulfides, aromatics, and even strained σ-bonds. Reduction is highly sensitive to substrate ionizability and permits selective reduction of the more ionizable function in a difunctional context. Ionization of the substrates to cation radicals is effected via the mild hole transfer agent tris(4-bromophenyl)aminium hexachloroantimonate, and subsequent reduction of the cation radicals is accomplished by tributyltin hydride. The new reduction conditions provide a novel route for generating free radicals which may prove useful in the field of radical cyclizations. This is especially attractive in the case of phenyl vinyl sulfides since the phenylthio group, which remains intact subsequent to cyclization, provides versatile functionality for further synthetic operations.
- Mirafzal, Gholam A.,Liu, Jianping,Bauld, Nathan L.
-
p. 6072 - 6077
(2007/10/02)
-
- CATALYSE PAR DES COMPLEXES DU NICKEL DE L'ELECTROSYNTHESE DE 1,1 DIARYLETHANE A PARTIR D'HALOGENURES AROMATIQUES ET D'ETHYLENE.
-
In mixed THF-HMPA, the electrochemical reduction of nickel bromide leads to catalytic nickel species very efficient towards the electro-reductive coupling of ethylene with arylhalides yielding 1,1-diarylethane as the main product.
- Rollin, Y,Meyer, G.,Troupel, M.,Fauvarque, J. F.
-
p. 3573 - 3576
(2007/10/02)
-