- Coupling Photocatalysis and Substitution Chemistry to Expand and Normalize Redox-Active Halides
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Photocatalysis can generate radicals in a controlled fashion and has become an important synthetic strategy. However, limitations due to the reducibility of alkyl halides prevent their broader implementation. Herein we explore the use of nucleophiles that can substitute the halide and serve as an electron capture motif that normalize the variable redox potentials across substrates. When used with photocatalysis, bench-stable, commercially available collidinium salts prove to be excellent radical precursors with a broad scope.
- Rathnayake, Manjula D.,Weaver, Jimmie D.
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supporting information
p. 2036 - 2041
(2021/04/05)
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- A heavy-metal-free desulfonylative Giese-type reaction of benzothiazole sulfones under visible-light conditions
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A visible-light-induced desulfonylative Giese-type reaction has been developed. Essential to the success is the employment of Hantzsch ester to activate benzothiazole sulfones without any heavy-metal additives. Not only benzylic benzothiazole sulfones but also alkyl ones were viable substrates and reacted with electron-deficient alkenes and a propiol amide.
- Inuzuka, Toshiyasu,Iwama, Haruka,Ogawa, Daichi,Sengoku, Tetsuya,Yoda, Hidemi
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supporting information
p. 9858 - 9861
(2021/10/12)
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- Nickel-Catalyzed Negishi-Type Arylation of Trialkylsulfonium Salts
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Negishi-type arylation of trialkylsulfonium salts with arylzinc reagents has been accomplished under nickel catalysis. The use of cyclohexanethiol as an additional ligand was found to be particularly important to promote C-S cleavage. The present reaction accommodates one-pot arylation of dialkyl sulfides by combining with S -methylation with MeOTf. Mechanistic experiments suggest that C-S cleavage would proceed via single-electron transfer (SET) to generate the most stable carbon-centered radical and that the thiolate ligand would promote the C-S cleavage and radical recombination step.
- Minami, Hiroko,Nogi, Keisuke,Yorimitsu, Hideki
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supporting information
p. 1542 - 1546
(2021/09/06)
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- Preparation method of alkyl nitrile compound
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The invention discloses a preparation method of an alkyl nitrile compound. Specifically, the preparation method comprises the following step: in an organic solvent, in the presence of a protective gasand under the action of a catalyst, carrying out a reduction reaction as shown in the specification on olefin as shown in a formula I, a cyanation reagent and water, wherein the alkyl nitrile compound 1 is a compound II and/or a compound III. The preparation method provided by the invention is mild in condition, can realize hydrocyanation of olefin more safely and efficiently, and has good substrate universality and functional group compatibility.
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Paragraph 0214-0219
(2020/08/18)
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- Low-Valent Titanium-Mediated Radical Conjugate Addition Using Benzyl Alcohols as Benzyl Radical Sources
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A concise method to directly generate benzyl radicals from benzyl alcohol derivatives has been developed. The simple and inexpensive combination of TiCl4(collidine) (collidine = 2,4,6-collidine) and manganese powder afforded a low-valent titanium reagent, which facilitated homolytic cleavage of benzylic C-OH bonds. The application to radical conjugate addition reactions demonstrated the broad scope of this method. The reaction of various benzyl alcohol derivatives with electron-deficient alkenes furnished the corresponding radical adducts.
- Suga, Takuya,Shimazu, Shoma,Ukaji, Yutaka
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supporting information
p. 5389 - 5392
(2018/09/12)
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- Visible-Light-Mediated Remote γ-C(sp3)-H Functionalization of Alkylimidates: Synthesis of 4-Iodo-3,4-dihydropyrrole Derivatives
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An efficient and environmentally friendly synthetic approach toward functionalized dihydropyrrole derivatives is reported. The developed protocol proceeds via chemoselective intramolecular N-C bond formation of alkylimidates through 1,5-hydrogen atom transfer from in situ generated imidate N-radicals. The major advantage of this designed strategy lies in the choice of starting materials, mild reaction conditions, high chemo- and diastereoselectivity, clean source of energy, and good functional group tolerance. Further, 4-iododihydropyrroles could be easily transformed into a variety of useful derivatives.
- Kumar, Yogesh,Jaiswal, Yogesh,Kumar, Amit
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supporting information
p. 4964 - 4969
(2018/08/24)
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- Nickel-Catalyzed 1,2-Aminoarylation of Oxime Ester-Tethered Alkenes with Boronic Acids
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A nickel-catalyzed 1,2-aminoarylation of oxime-ester-tethered alkenes with boronic acids was developed. A variety of pyrroline derivatives were synthesized in good yields via the successive formation of C(sp3)-N and C(sp3)-C(sp2) bonds. For cyclobutanone-derived oxime esters, the reaction provided aliphatic nitriles incorporating an aromatic group in the γ-position. A mechanism involving iminyl radical and carbon-centered radical intermediates was proposed.
- Yang, Hai-Bin,Pathipati, Stalin R.,Selander, Nicklas
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p. 8441 - 8445
(2017/12/08)
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- A Lewis Base Catalysis Approach for the Photoredox Activation of Boronic Acids and Esters
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We report herein the use of a dual catalytic system comprising a Lewis base catalyst such as quinuclidin-3-ol or 4-dimethylaminopyridine and a photoredox catalyst to generate carbon radicals from either boronic acids or esters. This system enabled a wide range of alkyl boronic esters and aryl or alkyl boronic acids to react with electron-deficient olefins via radical addition to efficiently form C?C coupled products in a redox-neutral fashion. The Lewis base catalyst was shown to form a redox-active complex with either the boronic esters or the trimeric form of the boronic acids (boroxines) in solution.
- Lima, Fabio,Sharma, Upendra K.,Grunenberg, Lars,Saha, Debasmita,Johannsen, Sandra,Sedelmeier, Joerg,Van der Eycken, Erik V.,Ley, Steven V.
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supporting information
p. 15136 - 15140
(2017/11/20)
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- Continuous UV-Flow Microsystem for Efficient Radical Generation from Organotrifluoroborates by Photoredox Catalysis
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An efficient continuous-flow protocol for C–O and C–C bond formation from organoborates by photoredox catalysis under UV irradiation was explored. The combination of a cyclometalated iridium photocatalyst, high-power UV light-emitting diode irradiation, and microreactor technology resulted in very efficient radical generation. The flow device enabled determination of highly accurate kinetic data that allowed the observation of good correlations with the standard Hammett σ (–0.26 to 0.227) values for a wide variety of substituents on the benzyl moiety (? = –4.70, R2= 0.98). Good to excellent yields were obtained for a variety of substrates by applying significantly short residence times.
- El Achi, Nassim,Penhoat, Ma?l,Bakkour, Youssef,Rolando, Christian,Chausset-Boissarie, La?titia
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supporting information
p. 4284 - 4288
(2016/09/13)
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- Visible light-induced selective generation of radicals from organoborates by photoredox catalysis
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A new strategy for the generation of carbon-centered radicals via oxidation of alkyl-, allyl-, benzyl- and arylborates by visible-light-driven single electron transfer (SET) photoredox catalysis has been established. The generated radicals smoothly react with TEMPO and electron-deficient alkenes to afford C-O and C-C coupling products, respectively. In this radical initiating system, cyclic organo(triol)borates turn out to be useful radical precursors.
- Yasu, Yusuke,Koike, Takashi,Akita, Munetaka
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supporting information
p. 3414 - 3420
(2013/02/25)
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- Iron-catalyzed chemoselective cross-coupling of primary and secondary alkyl halides with arylzinc reagents
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Functional-group-compatible cross-coupling reaction of alkyl halides with arylzinc reagents takes place under iron catalysis in the presence of TMEDA, producing a variety of aromatic compounds in good to excellent yield. The pronounced effect of a magnesium salt was found to be the key to the promotion of the iron-catalyzed coupling reaction. Georg Thieme Verlag Stuttgart.
- Nakamura, Masaharu,Ito, Shingo,Matsuo, Keiko,Nakamura, Eiichi
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p. 1794 - 1798
(2007/10/03)
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- Facile preparation of organozinc bromides using electrogenerated highly reactive zinc and its use in cross-coupling reaction
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Highly reactive zinc was readily prepared by electrolysis of a DMF solution containing pyrene as a mediator with a platinum cathode and a zinc anode. Preferential reduction of pyrene occurred to generate the corresponding radical anion, which reduced zinc ions generated from anodic dissolution to give zero valent zinc with high reactivity. The reactive zinc was successfully used for an efficient transformation of bromoalkanes into the corresponding organozinc bromides. Organozinc bromides obtained were further used successfully in Pd-catalyzed cross-coupling reaction with various aryl iodides and bromides.
- Kurono, Nobuhito,Inoue, Tomio,Tokuda, Masao
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p. 11125 - 11131
(2007/10/03)
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- One-step cross-coupling reaction of functionalized alkyl iodides with aryl halides by the use of an electrochemical method
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Organozinc compounds of functionalized alkyl iodide carrying an alkoxycarbonyl, cyano or alkenyl group were prepared in high yields under mild conditions (0°C-r.t., 10min in DMF) by the reaction of iodides with an electrogenerated reactive zinc (EGZn). Cross-coupling of the organozinc compounds with various aryl halides in the presence of 5 mol% Pd(P(o- Tol)3)2Cl2 in THF gave the corresponding cross-coupled products in moderate to high yields. These cross-coupling reactions can be also achieved in one step and in one pot by the use of an electrochemical method utilizing a Pt cathode and Zn anode.
- Kurono, Nobuhito,Sugita, Kazuya,Takasugi, Shingo,Tokuda, Masao
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p. 6097 - 6108
(2007/10/03)
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- Cyclic imino derivatives and pharmaceutical compositions containing them
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The invention relates to cyclic imino compounds which have, inter alia, valuable pharmacological properties, especially inhibitory effects on cell aggregation, pharmaceutical compositions which contain these compounds and processes for preparing them.
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- 7-oxabicycloheptyl substituted heterocyclic amide or ester prostaglandin analogs useful in the treatment of thrombotic and vasospastic disease
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7-Oxabicycloheptane substituted prostaglandin analogs useful in treating thrombotic and vasopastic disease have the structural formula STR1 wherein m is 1, 2 or 3; n is 1, 2, 3 or 4; Z is --(CH2)2 --, --CH=CH-- or STR2 wherein Y is O, a single bond or vinyl, with the proviso that when n is 0, if Z is STR3 then Y cannot be O, and Z is --CH=CH--, n is 1, 2, 3 or 4; and when Y=vinyl, n=0; R is CO2 H, CO2 lower alkyl, CH2 OH, CO2 alkali metal, CONHSOR3, CONHR3a or --CH2 --5-tetrazolyl, X is O, S or NH; and where R1, R2, R3 and R3a are as defined herein.
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- Liquid Crystalline trans-4-(ω-Cyanalkyl)cyclohexylester and 4-(ω-Cyanalkyl)phenylesters
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The synthesis of the title esters 1 and 2a-e (n = 0-3) and their mesomorphic properties are described.When the alkyl-spacer n between the polar CN-group and the cyclohexane ring of cyanalkyl-cyclohexylesters 1 is increased the difference of the clearing points between the phenylesters 2 and the cyclohexylesters 1 decreases to nearly zero.The reason of higher clearing temperatures of 2 is a dynamic conformational effect of ring inversion of cyclohexane in the ester 1 with two polar substituents at the ring.
- Deutscher, H.-J.,Krieg, R.,Frach, R.,Kresse, H.,Zaschke, H.
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p. 963 - 974
(2007/10/02)
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