13524-73-7Relevant academic research and scientific papers
The preparation and use of polyHIPE-grafted reactants to reduce alkyl halides under free-radical conditions
Chemin, Alexandre,Mercier, Anthony,Deleuze, Herve,Maillard, Bernard,Mondain-Monval, Olivier
, p. 366 - 370 (2001)
PolyHIPE-supported tin hydride and thiol are synthesized to reduce alkyl bromides under free-radical conditions, taking advantage of the fully interconnected polyHIPE structure. Radical reduction of 1-bromoadamantane, 6-bromohex-1-ene and 1-allyloxy-2-bromobenzene are performed using two methodologies: one using supported tin hydride as reducing agent, and another using supported thiol as polarity-reversal catalyst in the presence of triethylsilane as reducing agent. The polyHIPE-supported tin hydride is used either in catalytic or stoichiometric amounts depending on the bromo compound to be reduced. In the case of unsaturated bromides, both methodologies lead to reductive cyclization, thus enabling radical rearrangement before hydrogen transfer. PolyHIPE-supported organotin hydride is a good alternative to tributyltin hydride to prevent tin contamination and facilitate product separation. PolyHIPE-supported thiol, in the presence of an excess of triethylsilane, shows good activity and selectivity toward reductive cyclization products. Results obtained by the two methodologies are compared and discussed.
Induction of radical cyclizations with the 10-methyl-9,10-dihydroacridine / NaBH4 photocatalytic system
Boisvert, Guy,Giasson, Richard
, p. 6587 - 6590 (1992)
The radical cyclization of suitably unsaturated aromatic halides, such as 1-allyloxy-2-halobenzenes (1a-d), can be induced with the 10-methyl-9,10-dihydroacridine / NaBH4 photocatalytic system in DMF. The method is preparatively useful with the most reactive halides.
Intermediacy of Aryl Radicals and Arylmetal Compounds in Reductive Dehalogenation of Halogenoarenes with Lithium Aluminium Hydride
Beckwith, Athelstan L. J.,Goh, Swee Hock
, p. 905 - 906 (1983)
Reduction of o-allyloxybromobenzene (1) with lithium aluminium hydride proceeds by two competing pathways; one involving aryl radicals is promoted by oxygen, the other affords initially an arylmetal compound.
Fast Tin-Free Hydrodehalogenation and Reductive Radical Cyclization Reactions: A New Reduction Process
Vaillard, Santiago E.,Postigo, Al,Rossi, Roberto A.
, p. 2037 - 2041 (2004)
The photostimulated reactions of several aryl and alkyl chlorides and bromides with the monoanion of reduced ethyl benzoate 5H furnish the reduced products in high yields. If the aryl moieties have suitable double bonds, the cyclized reduced products are obtained in high yields. The photostimulated reaction of 1-allyloxy-2-bromobenzene (1a) with 5H affords 3-methyl-2,3-dihydro-benzofuran (2a) in 97% yield. When 1-allyloxy-2-chlorobenzene (1b) is used, the yield of 2a is only 55%, which increases up to 91% when acetone enolate ion is added to the reaction mixture as entrainment reagent. With diallyl-(2-bromophenyl)amine (3a), and 2-allyloxy-1-halonaphthalenes (chloro, 4b, and bromo, 4a) the cyclized reduced products are obtained in yields above 96%. By competition experiments, 5H reacts ca. 5 times faster with 1-naphthyl radicals than benzenethiolate ions do, which is near the diffusion limit rate.
Radical cyclisation of 1-bromo-2-(prop-2-enyloxy)benzene using a polymer-supported organotin hydride
Lapotre,Deleuze,Maillard,Mulholland
, p. 3207 - 3218 (2001)
The use of polymer-supported organotin hydride for the cyclisation 1-bromo-2-(prop-2-enyloxy)benzene I to give 2,3-dihydro-3-methylbenzofuran II has been studied. The supports were prepared by suspension copolymerisation of an organotin-functionalised monomer. Two approaches have been investigated either using a stoichiometric or a catalytic amount of organotin support.
Radical cyclization reaction using a combination of phosphinic acid and a base in aqueous ethanol
Yorimitsu, Hideki,Shinokubo, Hiroshi,Oshima, Koichiro
, p. 104 - 105 (2000)
Treatment of allylic ether of 2-iodophenol or 2-haloethanal allylic acetal with phosphinic acid, a base and a radical initiator (AIBN or triethylborane) in aqueous ethanol provided the corresponding radical cyclization product in excellent yield. An addit
Photo-induced thiolate catalytic activation of inert Caryl-hetero bonds for radical borylation
K?nig, Burkhard,Wang, Hua,Wang, Shun
supporting information, p. 1653 - 1665 (2021/06/17)
Substantial effort is currently being devoted to obtaining photoredox catalysts with high redox power. Yet, it remains challenging to apply the currently established methods to the activation of bonds with high bond dissociation energy and to substrates with high reduction potentials. Herein, we introduce a novel photocatalytic strategy for the activation of inert substituted arenes for aryl borylation by using thiolate as a catalyst. This catalytic system exhibits strong reducing ability and engages non-activated Caryl–F, Caryl–X, Caryl–O, Caryl–N, and Caryl–S bonds in productive radical borylation reactions, thus expanding the available aryl radical precursor scope. Despite its high reducing power, the method has a broad substrate scope and good functional-group tolerance. Spectroscopic investigations and control experiments suggest the formation of a charge-transfer complex as the key step to activate the substrates.
Potent Reductants via Electron-Primed Photoredox Catalysis: Unlocking Aryl Chlorides for Radical Coupling
Chernowsky, Colleen P.,Cowper, Nicholas G. W.,Wickens, Zachary K.,Williams, Oliver P.
supporting information, (2020/02/04)
We describe a new catalytic strategy to transcend the energetic limitations of visible light by electrochemically priming a photocatalyst prior to excitation. This new catalytic system is able to productively engage aryl chlorides with reduction potentials hundreds of millivolts beyond the potential of Na0 in productive radical coupling reactions. The aryl radicals produced via this strategy can be leveraged for both carbon-carbon and carbon-heteroatom bond-forming reactions. Through direct comparison, we illustrate the reactivity and selectivity advantages of this approach relative to electrolysis and photoredox catalysis.
Radical Hydrodehalogenation of Aryl Bromides and Chlorides with Sodium Hydride and 1,4-Dioxane
Hokamp, Tobias,Dewanji, Abhishek,Lübbesmeyer, Maximilian,Mück-Lichtenfeld, Christian,Würthwein, Ernst-Ulrich,Studer, Armido
supporting information, p. 13275 - 13278 (2017/10/09)
A practical method for radical chain reduction of various aryl bromides and chlorides is introduced. The thermal process uses NaH and 1,4-dioxane as reagents and 1,10-phenanthroline as an initiator. Hydrodehalogenation can be combined with typical cyclization reactions, proving the nature of the radical mechanism. These chain reactions proceed by electron catalysis. DFT calculations and mechanistic studies support the suggested mechanism.
Pushing the Limits of Neutral Organic Electron Donors: A Tetra(iminophosphorano)-Substituted Bispyridinylidene
Hanson, Samuel S.,Doni, Eswararao,Traboulsee, Kyle T.,Coulthard, Graeme,Murphy, John A.,Dyker, C. Adam
supporting information, p. 11236 - 11239 (2016/07/06)
A new ground-state organic electron donor has been prepared that features four strongly π-donating iminophosphorano substituents on a bispyridinylidene skeleton. Cyclic voltammetry reveals a record redox potential of ?1.70 V vs. saturated calomel electrode (SCE) for the couple involving the neutral organic donor and its dication. This highly reducing organic compound can be isolated (44 %) or more conveniently generated in situ by a deprotonation reaction involving its readily prepared pyridinium ion precursor. This donor is able to reduce a variety of aryl halides, and, owing to its redox potential, was found to be the first organic donor to be effective in the thermally induced reductive S N bond cleavage of N,N-dialkylsulfonamides, and reductive hydrodecyanation of malonitriles.
