- Manganese(III)-Promoted Double Carbonylation of Anilines Toward α-Ketoamides Synthesis
-
Employing anilines as nucleophiles in double carbonylation is a longstanding challenge. In this communication, a Mn(III)-promoted double carbonylation of alkylborates or Hantzsch esters with anilines toward the synthesis of α-ketoamides has been developed. By using easily available potassium alkyltrifluoroborates or Hantzsch esters as the starting material, and cheap and non-toxic Mn(OAc)3 ? 2H2O as the promotor, a broad range of alkyl α-ketoamide derivatives were synthesized in moderate to good yields with excellent selectivity. (Figure presented.).
- Chen, Bo,Kuai, Chang-Sheng,Xu, Jian-Xing,Wu, Xiao-Feng
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supporting information
p. 487 - 492
(2021/12/06)
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- Light-Mediated Sulfur-Boron Exchange
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Interaction of sulfides bearing a tetrafluoropyridinyl group with bis(catecholato)diboron followed by treatment with pinacol and triethylamine affording pinacol boronic esters is described. The reaction is promoted by an organic photocatalyst (3DPA2FBN) u
- Panferova, Liubov I.,Dilman, Alexander D.
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supporting information
p. 3919 - 3922
(2021/05/29)
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- Site-Fixed Hydroboration of Terminal and Internal Alkenes using BX3/iPr2NEt**
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An unprecedented and general hydroboration of alkenes with BX3 (X=Br, Cl) as the boration reagent in the presence of iPr2NEt is reported. The addition of iPr2NEt not only suppresses alkene polymerizat
- Cui, Xin,Hu, Chenyang,Li, Sida,Liu, Liu Leo,Wu, Lipeng,Zhang, Jiong
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p. 26238 - 26245
(2021/11/09)
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- Carbon-carbon bond activation by B(OMe)3/B2pin2-mediated fragmentation borylation
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Selective carbon-carbon bond activation is important in chemical industry and fundamental organic synthesis, but remains challenging. In this study, non-polar unstrained Csp2-Csp3 and Csp2-Csp2 bond activation was achieved by B(OMe)3/B2pin2-mediated fragmentation borylation. Various indole derivatives underwent C2-regioselective C-C bond activation to afford two C-B bonds under transition-metal-free conditions. Preliminary mechanistic investigations suggested that C-B bond formation and C-C bond cleavage probably occurred in a concerted process. This new reaction mode will stimulate the development of reactions based on inert C-C bond activation. This journal is
- Chen, Quan,Jiang, Jiachen,Wang, Li,Wu, Aizhen,Yin, Youzhi,Zhang, Hua,Zhang, Ke,Zhao, Mengzhen,Zhong, Qi,Zou, Youliang
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p. 15104 - 15109
(2021/12/09)
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- Electrochemically promoted decarboxylative borylation of alkyl N-hydroxyphthalimide esters
-
An electrochemically promoted decarboxylative borylation reaction is reported. The reaction proceeds under mild conditions in an undivided cell without use of transition metal- or photo-catalysts. The key feature of the reaction is the compatibility of di
- Dai, Jian-Jun,Fang, Wen,Teng, Xin-Xin,Xu, Hua-Jian,Xu, Jun
-
-
- Chromium-Catalyzed Borylative Coupling of Aliphatic Bromides with Pinacolborane by Hydrogen Evolution
-
The chromium-catalyzed borylative coupling between aliphatic bromides and pinacolborane (HBpin) is described. This reaction was promoted by low-cost and bench-stable CrCl3as a precatalyst combined with 4,4′-di-tert-butyl-2,2′-dipyridyl and aluminum, presenting a rare example of using HBpin as a borane reagent by coupling with alkyl bromides in forming borylated alkanes. Mechanistic studies indicate that aluminum plays important roles in the formation of reactive Cr species and aliphatic radicals, which lead to (alkyl)Cr by reaction with HBpin to give the products.
- Fu, Aiping,Li, Chao,Luo, Meiming,Zeng, Xiaoming,Zhao, Lixing
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supporting information
p. 2204 - 2208
(2021/06/28)
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- Method for directly preparing alkyl borate compound from alkyl halide
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The invention relates to a method for directly preparing an alkyl borate compound from an alkyl halide, which comprises the following steps: in a protective atmosphere, mixing a titanium metal catalyst, an alkali compound, a borate compound and an alkyl halide or sulfonate compound, reacting at 35-100 DEG C for 8-24 hours, so that the alkyl halide or sulfonate compound is directly converted into the alkyl boronic acid pinacol ester compound. The method is simple to operate, low in cost, good in functional group tolerance and wide in substrate application range.
- -
-
Paragraph 0199-0201
(2021/04/14)
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- Catalytic Boration of Alkyl Halides with Borane without Hydrodehalogenation Enabled by Titanium Catalyst
-
An unprecedented and general titanium-catalyzed boration of alkyl (pseudo)halides (alkyl-X, X=I, Br, Cl, OMs) with borane (HBpin, HBcat) is reported. The use of titanium catalyst can successfully suppress the undesired hydrodehalogenation products that prevail using other transition-metal catalysts. A series of synthetically useful alkyl boronate esters are readily obtained from various (primary, secondary, and tertiary) alkyl electrophiles, including unactivated alkyl chlorides, with tolerance of other reducing functional groups such as ester, alkene, and carbamate. Preliminary studies on the mechanism revealed a possible radical reaction pathway. Further extension of our strategy to aryl bromides is also demonstrated.
- Wang, Xianjin,Cui, Penglei,Xia, Chungu,Wu, Lipeng
-
supporting information
p. 12298 - 12303
(2021/05/07)
-
- Preparation method of alkyl boride
-
The invention discloses a preparation method of alkyl boride. According to the method, alkyl halides (I, Br) and 2, 2 '-biphenyl [D] [1, 3, 2] dioxaborole (B2cat2) are used as raw materials, a properamount of electrolyte (optionally) is added, and the cor
- -
-
Paragraph 0033-0037
(2021/03/30)
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- Electrochemical Borylation of Alkyl Halides: Fast, Scalable Access to Alkyl Boronic Esters
-
Herein, a fast, scalable, and transition-metal-free borylation of alkyl halides (X = I, Br, Cl) enabled by electroreduction is reported. This process provides an efficient and practical access to primary, secondary, and tertiary boronic esters at a high current. More than 70 examples, including the late-stage borylation of natural products and drug derivatives, are furnished at room temperature, thereby demonstrating the broad utility and functional-group tolerance of this protocol. Mechanistic studies disclosed that B2cat2 serves as both a reagent and a cathodic mediator, enabling electroreduction of difficult-to-reduce alkyl bromides or chlorides at a low potential.
- Cao, Yangmin,Hu, Ping,Huang, Cheng,Liu, Zhao,Lu, Qingquan,Ma, Wan,Peng, Pan,Qi, Xiaotian,Wang, Bingbing
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supporting information
p. 12985 - 12991
(2021/09/03)
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- (o-Phenylenediamino)borylstannanes: Efficient Reagents for Borylation of Various Alkyl Radical Precursors
-
(o-Phenylenediamino)borylstannanes were newly synthesized to achieve radical boryl substitutions of a variety of alkyl radical precursors. Dehalogenative, deaminative, decharcogenative, and decarboxylative borylations proceeded in the presence of a radica
- Suzuki, Kensuke,Nishimoto, Yoshihiro,Yasuda, Makoto
-
supporting information
p. 3968 - 3973
(2020/12/30)
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- Photochemical synthesis method of alkyl borate compound
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The invention discloses a photochemical synthesis method of an alkyl borate compound. By taking alkane and duplex catechol borate as raw materials, coupling of carbon-boron bonds is realized under ultraviolet light illumination in the presence of an additive, and separating and purifying are carried out to obtain the alkyl borate compound. The photochemical synthesis method has the characteristics of high atom economy, greenness, high efficiency, avoidance of use of an oxidizing agent, simple process and the like, and is suitable for large-scale production.
- -
-
Paragraph 0027-0029
(2021/08/11)
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- Transition metal- And light-free radical borylation of alkyl bromides and iodides using silane
-
We report operationally simple and neutral conditions for borylation of alkyl bromides and iodides to alkyl boronic esters under transition metal- and light-free conditions. A series of substrates with a wide range of functional groups were effectively transformed into the borylation products in moderate to good yields. Mechanistic studies, including radical clock experiments and DFT calculations, gave detailed insight into the radical borylation process.
- Mo, Fanyang,Sun, Beiqi,Zheng, Sihan
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supporting information
p. 5674 - 5677
(2021/06/16)
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- Mild and Selective Rhodium-Catalyzed Transfer Hydrogenation of Functionalized Arenes
-
Diboron-mediated rhodium-catalyzed transfer hydrogenation of functionalized arenes is reported. In addition to good functional group tolerance, the reaction features operational simplicity and controllable chemoselectivity. The general applicability of this procedure is demonstrated by the selective hydrogenation of a range of arenes, including functionalized benzenes, biphenyls, and polyaromatics.
- Wang, Yuhan,Chang, Zhiqian,Hu, Yan,Lin, Xiao,Dou, Xiaowei
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supporting information
p. 1910 - 1914
(2021/03/08)
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- Copper-Photocatalyzed Hydroboration of Alkynes and Alkenes
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The photocatalytic hydroboration of alkenes and alkynes is reported. The use of newly-designed copper photocatalysts with B2Pin2 permits the formation a boryl radical, which is used for hydroboration of a large panel of alkenes and a
- Zhong, Mingbing,Gagné, Yohann,Hope, Taylor O.,Pannecoucke, Xavier,Frenette, Mathieu,Jubault, Philippe,Poisson, Thomas
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supporting information
p. 14498 - 14503
(2021/05/21)
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- Visible-light-driven graphene supported Cu/Pd alloy nanoparticle-catalyzed borylation of alkyl bromides and chlorides in air
-
A highly efficient photocatalytic protocol for borylation of alkyl bromides and chlorides with graphene supported Cu/Pd alloy nanoparticles as a heterogeneous catalyst is reported. This photocatalytic system operates with visible light in air, providing a wide range of primary and secondary alkyl halides with B2pin2 or B2neop2 in high yields at low temperatures, thereby demonstrating its broad utility and functional group tolerance. The high performance is attributed to a synergistic effect of localized surface plasmon resonance (LSPR) of Cu and charge transfer from Cu to Pd due to the alloy surface charge heterogeneity. Transfer of energetic electrons from Pd to electrophilic alkyl halides lead to the formation of the alkyl radicals, which quickly react with a nucleophilic adduct of a diboron compound with base adsorbed on the positively charged Cu sites to form the corresponding borylation product.
- Jiao, Zhi-Feng,Tian, Ya-Ming,Guo, Xiao-Ning,Radius, Udo,Braunschweig, Holger,Marder, Todd B.,Guo, Xiang-Yun
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p. 258 - 265
(2021/02/16)
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- Evaluation of the role of graphene-based Cu(i) catalysts in borylation reactions
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Carbon-supported catalysts have been considered as macromolecular ligands which modulate the activity of the metallic catalytic center. Understanding the properties and the factors that control the interactions between the metal and support allows a fine tuning of the catalyzed processes. Although huge effort has been devoted to comprehending binding energies and charge transfer for single atom noble metals, the interaction of graphenic surfaces with cheap and versatile Cu(i) salts has been scarcely studied. A methodical experimental and theoretical analysis of different carbon-based Cu(i) materials in the context of the development of an efficient, general, scalable, and sustainable borylation reaction of aliphatic and aromatic halides has been performed. We have also examined the effect of microwave (MW) radiation in the preparation of these type of materials using sustainable graphite nanoplatelets (GNP) as a support. A detailed analysis of all the possible species in solution revealed that the catalysis is mainly due to an interesting synergetic Cu2O/graphene performance, which has been corroborated by an extensive theoretical study. We demonstrated through DFT calculations at a high level of theory that graphene enhances the reactivity of the metal in Cu2O against the halide derivative favoring a radical departure from the halogen. Moreover, this material is able to stabilize radical intermediates providing unexpected pathways not observed using homogeneous Cu(i) catalysed reactions. Finally, we proved that other common carbon-based supports like carbon black, graphene oxide and reduced graphene oxide provided poorer results in the borylation process.
- Cid, M. B.,Díaz, Cristina,Franco, Mario,Lamsabhi, Al Mokhtar,Sainz, Raquel,Tortosa, Mariola
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p. 3501 - 3513
(2021/06/06)
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- Photochemical Radical C–H Halogenation of Benzyl N-Methyliminodiacetyl (MIDA) Boronates: Synthesis of α-Functionalized Alkyl Boronates
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α-Haloboronates are useful organic synthons that can be converted to a diverse array of α-substituted alkyl borons. Methods to α-haloboronates are limiting and often suffer from harsh reaction conditions. Reported herein is a photochemical radical C-H halogenation of benzyl N-methyliminodiacetyl (MIDA) boronates. Fluorination, chlorination, and bromination reactions were effective by using this protocol. Upon reaction with different nucleophiles, the C?Br bond in the brominated product could be readily transformed to a series of C?C, C?O, C?N, C?S, C?P, and C?I bonds, some of which are difficult to forge with α-halo sp2-B boronate esters. An activation effect of B(MIDA) moiety was found.
- Yang, Ling,Tan, Dong-Hang,Fan, Wen-Xin,Liu, Xu-Ge,Wu, Jia-Qiang,Huang, Zhi-Shu,Li, Qingjiang,Wang, Honggen
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supporting information
p. 3454 - 3458
(2020/12/17)
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- A General Approach to Deboronative Radical Chain Reactions with Pinacol Alkylboronic Esters
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The generation of carbon-centered radicals from air-sensitive organoboron compounds through nucleohomolytic substitution at boron is a general method to generate non-functionalized and functionalized radicals. Due to their reduced Lewis acidity, alkylboronic pinacol esters are not suitable substrates. We report their in situ conversion into alkylboronic catechol esters by boron-transesterification with a substoichiometric amount of catechol methyl borate combined with an array of radical chain processes. This simple one-pot radical-chain deboronative method enables the conversion of pinacol boronic esters into iodides, bromides, chlorides, and thioethers. The process is also suitable the formation of nitriles and allylated compounds through C?C bond formation using sulfonyl radical traps. The power of combining radical and classical boron chemistry is illustrated with a modular 5-membered ring formation using a combination of three-component coupling and protodeboronative cyclization.
- André-Joyaux, Emy,Kuzovlev, Andrey,Renaud, Philippe,Tappin, Nicholas D. C.
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supporting information
p. 13859 - 13864
(2020/06/10)
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- Decarboxylative Borylation of Stabilized and Activated Carbon Radicals
-
Redox-active esters (RAEs) as active radical precursors have been extensively studied for C?B bond formations. However, the analogous transformations of stabilized radicals from the corresponding acid precursors remain challenging owing to the strong preference towards single-electron oxidation to the stable carbocations. This work describes a general strategy for rapid access to various aliphatic and aromatic boronic esters by mild photoinduced decarboxylative borylation. Both aryl and alkyl radicals could be generated from the leaving group-assisted N-hydroxybenzimidoyl chloride esters, even α-CF3 substituted substrates could be activated for further elaboration.
- Li, Xiaojuan,Ni, Shengyang,Pan, Yi,Wang, Yi,Zhang, Qiang,Zhang, Weigang
-
supporting information
p. 21875 - 21879
(2020/10/02)
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- Metal-free photoinduced C(sp 3)–H borylation of alkanes
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Boronic acids and their derivatives are some of the most useful reagents in the chemical sciences1, with applications spanning pharmaceuticals, agrochemicals and functional materials. Catalytic C–H borylation is a powerful method for introducing these and other boron groups into organic molecules because it can be used to directly functionalize C–H bonds of feedstock chemicals without the need for substrate pre-activation1–3. These reactions have traditionally relied on precious-metal catalysts for C–H bond cleavage and, as a result, display high selectivity for borylation of aromatic C(sp2)–H bonds over aliphatic C(sp3)–H bonds4. Here we report a mechanistically distinct, metal-free borylation using hydrogen atom transfer catalysis5, in which homolytic cleavage of C(sp3)–H bonds produces alkyl radicals that are borylated by direct reaction with a diboron reagent. The reaction proceeds by violet-light photoinduced electron transfer between an N-alkoxyphthalimide-based oxidant and a chloride hydrogen atom transfer catalyst. Unusually, stronger methyl C–H bonds are borylated preferentially over weaker secondary, tertiary and even benzylic C–H bonds. Mechanistic studies indicate that the high methyl selectivity is a result of the formation of a chlorine radical–boron ‘ate?? complex that selectively cleaves sterically unhindered C–H bonds. By using a photoinduced hydrogen atom transfer strategy, this metal-free C(sp3)–H borylation enables unreactive alkanes to be transformed into valuable organoboron reagents under mild conditions and with selectivities that contrast with?those of established metal-catalysed protocols.
- Shu, Chao,Noble, Adam,Aggarwal, Varinder K.
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p. 714 - 719
(2020/11/02)
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- Boron esterification reaction method without transition metal catalysis of alkyl bromide (by machine translation)
-
The present invention discloses a method. of synthesizing alkylborate, using an alkyl bromide compound 1 equivalent of a diborate, 1 - 5 equivalent amount of a radical initiator in an organic solvent, 1 - 5 in the presence of a metal catalyst, 1 - 5 and r
- -
-
Paragraph 0040-0041
(2020/03/29)
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- Photoinduced Radical Borylation of Alkyl Bromides Catalyzed by 4-Phenylpyridine
-
Utilizing pyridine catalysis, we developed a visible-light-induced transition-metal-free radical borylation reaction of unactivated alkyl bromides that features a broad substrate scope and mild reaction conditions. Mechanistic studies revealed a novel nucleophilic substitution/photoinduced radical formation pathway, which could be utilized to trigger a variety of radical processes.
- Zhang, Li,Wu, Zhong-Qian,Jiao, Lei
-
supporting information
p. 2095 - 2099
(2019/12/24)
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- Visible-light-mediated borylation of aryl and alkyl halides with a palladium complex
-
Palladium catalyzed visible-light-mediated borylation of inactivated aryl and alkyl halides is reported; the method provided high yields and excellent functional group compatibility. Furthermore, arylsilicates were synthesized selectively using dimethylphenylsilyl boronic ester via changing the reaction conditions. Finally, the possible reaction mechanism is determined through fluorescence quenching and turn on/off experiments.
- Zhao, Jia-Hui,Zhou, Zhao-Zhao,Zhang, Yue,Su, Xuan,Chen, Xi-Meng,Liang, Yong-Min
-
supporting information
p. 4390 - 4394
(2020/10/20)
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- Decarboxylative Borylation of mCPBA-Activated Aliphatic Acids
-
A decarboxylative borylation of aliphatic acids for the synthesis of a variety of alkylboronates has been developed by mixing m-chloroperoxybenzoic acid (mCPBA)-activated fatty acids with bis(catecholato)diboron in N,N-dimethylformamide (DMF) at room temperature. A radical chain process is involved in the reaction which initiates from the B-B bond homolysis followed by the radical transfer from the boron atom to the carbon atom with subsequent decarboxylation and borylation.
- Wei, Dian,Liu, Tu-Ming,Zhou, Bo,Han, Bing
-
supporting information
p. 234 - 238
(2020/01/02)
-
- Catalytic Transfer Hydrogenation of Arenes and Heteroarenes
-
Transfer hydrogenation reactions are of great interest to reduce diverse molecules under mild reaction conditions. To date, this type of reaction has only been successfully applied to alkenes, alkynes and polarized unsaturated compounds such as ketones, imines, pyridines, etc. The reduction of benzene derivatives by transfer hydrogenation has never been described, which is likely due to the high energy barrier required to dearomatize these compounds. In this context, we have developed a catalytic transfer hydrogenation reaction for the reduction of benzene derivatives and heteroarenes to form complex 3-dimensional scaffolds bearing various functional groups at room temperature without needing compressed hydrogen gas.
- Gelis, Coralie,Heusler, Arne,Nairoukh, Zackaria,Glorius, Frank
-
supporting information
p. 14090 - 14094
(2020/10/19)
-
- Efficient synthesis of alkylboronic esters: Via magnetically recoverable copper nanoparticle-catalyzed borylation of alkyl chlorides and bromides
-
We report a magnetically separable Cu nanocatalyst (Fe-DOPA-Cu) for the borylation of alkyl halides with alkoxy diboron reagents, providing alkylboronic esters in high yields, with broad functional group tolerance under mild reaction conditions. The procedure is also applicable to the borylation of benzyl chlorides and bromides. Radical clock experiments support a radical-mediated process. Easy recycling of the catalyst resulted in no significant loss of activity up to ten runs.
- Shegavi, Mahadev L.,Agarwal, Abhishek,Bose, Shubhankar Kumar
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supporting information
p. 2799 - 2803
(2020/06/17)
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- Cobalt(I)-Catalyzed Borylation of Unactivated Alkyl Bromides and Chlorides
-
A cobalt-complex-catalyzed borylation of a wide range of alkyl halides with a diboron reagent (B2pin2 or B2neop2) has been developed under mild reaction conditions, demonstrating the first cobalt-mediated cross-coupling with alkyl electrophiles. This protocol allows alkyl boronic esters to be accessed from alkyl halides, including alkyl chlorides, which were used rarely as coupling partners. Mechanistic studies reveal the possible involvement of an alkyl radical intermediate in this cobalt-mediated catalytic cycle.
- Geetharani, K.,Prasad, K. Sujit,Varghese, Dominic,Verma, Piyush Kumar
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supporting information
p. 1431 - 1436
(2020/03/13)
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- Hydroboration of terminal olefins with pinacolborane catalyzed by new 2-iminopyrrolyl iron(ii) complexes
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Four paramagnetic 14-electron tetracoordinated Fe(ii) complexes of 5-substituted-2-iminopyrrolyl ligands of the type [Fe{κ2N,N′-5-R-NC4H2-2-C(H)N(2,6-iPr2-C6H3)}(Py)Cl], with R = 2,6-Me2-C6H3 (1a), 2,4,6-iPr3-C6H2 (1b), 2,4,6-Ph3-C6H3 (1c) and CPh3 (1d), were synthesized in moderate yields by reacting the respective 5-substituted-2-iminopyrrolyl potassium salts KLa-d with FeCl2(Py)4 in toluene. Complexes 1a-d were characterized by 1H NMR, FTIR spectroscopies, elemental analysis and by the Evans method, the corresponding effective magnetic moments showing a high-spin electronic nature. X-ray diffraction studies on complexes 1a and 1c showed distorted tetrahedral coordination geometries. Complexes 1a-c, activated with K(HBEt3), were efficient catalyst systems for the hydroboration of several terminal alkenes with pinacolborane in good to high yields (50-90%). This system mainly yielded the respective anti-Markovnikov addition products, except when styrenes were used. A screening of the hydroboration of styrene catalyzed by complexes 1a-c activated with K(HBEt3) showed that the selectivity in the Markovnikov product increased with increasing steric bulkiness of the R group, exhibiting selectivities up to 91%. Additionally, the stoichiometric reaction of complex 1b with K(HBEt3) over 30 minutes yielded the mixture of hydride species 2 and 22 (mixture I). On the other hand, when reacting the same components over 16 h, the Fe(i) complex 3 was also identified in the mixture, in addition to 2 + 22 (mixture II). These mixtures were characterized in solution by the Evans method and in the solid state by elemental analysis, 57Fe M?ssbauer and FTIR spectroscopies, compounds 22 and 3 being also analyzed by X-ray diffraction. These results suggest that the corresponding catalytic cycle follows the borane oxidative addition route to a Fe(i) species.
- Cruz, Tiago F. C.,Pereira, Laura C. J.,Waerenborgh, Jo?o C.,Veiros, Luís F.,Gomes, Pedro T.
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p. 3347 - 3360
(2019/07/10)
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- Lithium compounds as single site catalysts for hydroboration of alkenes and alkynes
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The hydroboration of alkenes and alkynes using easily accessible lithium compounds [2,6-di-tert-butyl phenolatelithium (1a) and 1,1′ dilithioferrocene (1b)] has been achieved with good yields, high functional group tolerance and excellent chemoselectivity
- Bisai, Milan Kumar,Yadav, Sandeep,Das, Tamal,Vanka, Kumar,Sen, Sakya S.
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supporting information
p. 11711 - 11714
(2019/10/02)
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- Hydrogen Atom Transfer Induced Boron Retaining Coupling of Organoboronic Esters and Organolithium Reagents
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α-Functionalization of alkyl boronic esters and homologation of aryl boronic esters by regioselective radical C(sp3)-H activation in boron-ate complexes is reported. Reaction of commercial or readily accessed aryl boronic acid pinacol esters with alkyl lithium reagents provides boron-ate complexes. Selective α-C-H abstraction by in situ generated trifluoromethyl radicals leads to radical anions that undergo electron transfer oxidation followed by 1,2-aryl/alkyl migration from boron to carbon to give the α-arylated/alkylated alkyl boronic esters. The valuable boronic ester functionality remains in the products and the cheap trifluoromethyl iodide acts as the oxidant in these C-C couplings. The 1,2-alkyl migration from boron to carbon is highly stereospecific allowing access to stereoisomerically pure boronic esters.
- Wang, Dinghai,Mück-Lichtenfeld, Christian,Studer, Armido
-
supporting information
p. 14126 - 14130
(2019/10/11)
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- Transition-Metal-Free Borylation of Alkyl Iodides via a Radical Mechanism
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We describe an operationally simple transition-metal-free borylation of alkyl iodides. This method uses commercially available diboron reagents as the boron source and exhibits excellent functional group compatibility. Furthermore, a diverse range of prim
- Liu, Qianyi,Hong, Junting,Sun, Beiqi,Bai, Guangcan,Li, Feng,Liu, Guoquan,Yang, Yang,Mo, Fanyang
-
supporting information
(2019/07/08)
-
- Hydrogenation of (Hetero)aryl Boronate Esters with a Cyclic (Alkyl)(amino)carbene–Rhodium Complex: Direct Access to cis-Substituted Borylated Cycloalkanes and Saturated Heterocycles
-
We herein report the hydrogenation of substituted aryl- and heteroaryl boronate esters for the selective synthesis of cis-substituted borylated cycloalkanes and saturated heterocycles. A cyclic (alkyl)(amino)carbene-ligated rhodium complex with two dimethyl groups at the ortho-alkyl scaffold of the carbene showed high reactivity in promoting the hydrogenation, thereby enabling the hydrogenation of (hetero)arenes with retention of the synthetically valuable boronate group. This process constitutes a clean, atom-economic, as well as chemo- and stereoselective route for the generation of cis-configured, diversely substituted borylated cycloalkanes and saturated heterocycles that are usually elusive and difficult to prepare.
- Ling, Liang,He, Yuan,Zhang, Xue,Luo, Meiming,Zeng, Xiaoming
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p. 6554 - 6558
(2019/04/17)
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- Hydrogenation of Borylated Arenes
-
A cis-selective hydrogenation of abundant aryl boronic acids and their derivatives catalyzed by rhodium cyclic (alkyl)(amino)carbene (Rh–CAAC) is reported. The reaction tolerates a variety of boron-protecting groups and provides direct access to a broad s
- Wollenburg, Marco,Moock, Daniel,Glorius, Frank
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p. 6549 - 6553
(2019/01/04)
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- Synthesis of functionalized organoboron/silicon compounds by copper-catalyzed coupling of alkylsilyl peroxides and diboron/silylborane reagents
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The facile synthesis of functionalized organoboron/silicon compounds by copper-catalyzed coupling of alkylsilyl peroxides and diboron/silylborane reagents is reported. The reactions proceed smoothly under mild, neutral conditions in short reaction times t
- Seihara, Takumi,Sakurai, Shunya,Kato, Terumasa,Sakamoto, Ryu,Maruoka, Keiji
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supporting information
p. 2477 - 2481
(2019/04/10)
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- Free Radical Pathway Cleavage of C—O Bonds for the Synthesis of Alkylboron Compounds
-
We report a silver-catalyzed borylation of alkyl tosylates, which provides a new method for the synthesis of alkylboron compounds with good functional group compatibility and excellent chemoselectivity. The present work added highly polarized alkyl tosylate C—O bonds to the fairly limited number of C—O bonds able to participate in free radical cleavage pathways. The mechanistic studies suggested that in situ-generated silver(0) catalytic species were the active catalytic species and played a key role in the radical pathway cleavage of C—O bonds.
- Lu, Xi,Zhang, Zhen-Qi,Yu, Lu,Zhang, Ben,Wang, Bing,Gong, Tian-Jun,Tian, Chang-Lin,Xiao, Bin,Fu, Yao
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supporting information
p. 11 - 18
(2018/12/13)
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- Alkyl-halide boron esterification reaction method free from transition metal catalysis
-
The invention discloses an alkyl-halide boron esterification reaction method free from transition metal catalysis. The method has the advantages that the transition metal catalysis is not needed, boric acid ester serves as a boron source, alkoxide serves
- -
-
Paragraph 0073; 0074
(2019/04/17)
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- Metal-Free Radical Borylation of Alkyl and Aryl Iodides
-
A metal-free radical borylation of alkyl and aryl iodides with bis(catecholato)diboron (B2cat2) as the boron source under mild conditions is introduced. The borylation reaction is operationally easy to conduct and shows high functional group tolerance and broad substrate scope. Radical clock experiments and density functional theory calculations provide insights into the mechanism and rate constants for C-radical borylation with B2cat2 are disclosed.
- Cheng, Ying,Mück-Lichtenfeld, Christian,Studer, Armido
-
supporting information
p. 16832 - 16836
(2018/11/23)
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- Markovnikov-Selective Co(I)-Catalyzed Hydroboration of Vinylarenes and Carbonyl Compounds
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An NHC-supported Co(I) catalyst has been developed for selective Markovnikov hydroboration of vinylarenes under mild reaction conditions. The hydroboration allows highly selective synthesis of a wide range of secondary and tertiary alkyl boronates in exce
- Verma, Piyush Kumar,Sethulekshmi,Geetharani
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supporting information
p. 7840 - 7845
(2019/01/04)
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- Addition of a B-H Bond across an Amido-Cobalt Bond: CoII-H-Catalyzed Hydroboration of Olefins
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This paper describes a well-defined cobalt(II) half-sandwich complex bearing a phosphinoaminato ligand, Cp Co(1,2-Ph2PC6H4NH) (1), that can activate pinacolborane (HBpin) for catalytic terminal hydroboration of olefins. Th
- Pang, Maofu,Wu, Chengjuan,Zhuang, Xuewen,Zhang, Fanjun,Su, Mincong,Tong, Qingxiao,Tung, Chen-Ho,Wang, Wenguang
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p. 1462 - 1467
(2018/05/24)
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- Hydroboration of Terminal Olefins with Pinacolborane Catalyzed by New Mono(2-Iminopyrrolyl) Cobalt(II) Complexes
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The 5-substituted 2-aryliminopyrrolyl ligand precursors of the type 5-R-2-[N-(2,6-diisopropylphenyl)formimino]-1H-pyrrole (R = 2,6-Me2-C6H3 (1a), 2,4,6-iPr3-C6H2 (1b), 2,4,6-Phs
- Cruz, Tiago F. C.,Lopes, Patrícia S.,Pereira, Laura C. J.,Veiros, Luís F.,Gomes, Pedro T.
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supporting information
p. 8146 - 8159
(2018/07/25)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0238; 0243
(2019/01/07)
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- Synthesis of Trisubstituted Alkenyl Boronic Esters from Alkenes Using the Boryl-Heck Reaction
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The direct borylation of disubstituted alkenes is reported. These conditions allow for the conversion of a variety 1,1- and 1,2-disubstituted alkenes to trisubstituted alkenyl boronic esters with outstanding yields and excellent E/Z selectivities. The utility of this reaction has been demonstrated with several downstream functionalization reactions, which allow access to diverse, stereodefined, functionalized olefins. Mechanistic studies are consistent with a boryl-Heck pathway.
- Reid, William B.,Watson, Donald A.
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supporting information
p. 6832 - 6835
(2018/10/24)
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- Photoinduced Deaminative Borylation of Alkylamines
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An operationally simple deaminative borylation reaction of primary alkylamines has been developed. The formation of electron-donor-acceptor complexes between N-alkylpyridinium salts and bis(catecholato)diboron enables photoinduced single-electron transfer and fragmentation to carbon-centered radicals, which are subsequently borylated. The mild conditions allow a diverse range of readily available alkylamines to be efficiently converted into synthetically valuable alkylboronic esters under catalyst-free conditions.
- Wu, Jingjing,He, Lin,Noble, Adam,Aggarwal, Varinder K.
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supporting information
p. 10700 - 10704
(2018/09/06)
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- Deaminative Borylation of Aliphatic Amines Enabled by Visible Light Excitation of an Electron Donor–Acceptor Complex
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A deaminative strategy for the borylation of aliphatic primary amines is described. Alkyl radicals derived from the single-electron reduction of redox-active pyridinium salts, which can be isolated or generated in situ, were borylated in a visible light-mediated reaction with bis(catecholato)diboron. No catalyst or further additives were required. The key electron donor–acceptor complex was characterized in detail by both experimental and computational investigations. The synthetic potential of this mild protocol was demonstrated through the late-stage functionalization of natural products and drug molecules.
- Sandfort, Frederik,Strieth-Kalthoff, Felix,Klauck, Felix J. R.,James, Michael J.,Glorius, Frank
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supporting information
p. 17210 - 17214
(2018/11/10)
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- Selective C?N Borylation of Alkyl Amines Promoted by Lewis Base
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An efficient method for the metal-free deaminative borylation of alkylamines, using bis(catecholato)diboron as the boron source, to directly synthesize various alkyl potassium trifluoroborate salts is introduced. The key to this high reactivity is the utilization of pyridinium salt activated alkylamines, with a catalytic amount of a bipyridine-type Lewis base as a promoter. This transformation shows good functional-group compatibility (e.g., it is unimpeded by the presence of a ketone, indole, internal alkene, or unactivated alkyl chloride) and can serve as a powerful synthetic tool for borylation of amine groups in complex compounds. Mechanistic experiments and computations suggest a mechanism in which the Lewis base activated B2cat2 unit intercepts an alkyl radical generated by single-electron transfer (SET) from a boron-based reductant.
- Hu, Jiefeng,Wang, Guoqiang,Li, Shuhua,Shi, Zhuangzhi
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supporting information
p. 15227 - 15231
(2018/10/25)
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- Ambient-Pressure Asymmetric Preparation of S,S -DICHED, a C 2 -Symmetrical Director for Matteson Reactions
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A synthesis of S, S -DICHED (dicyclohexylethane-1,2-diol), a C 2 -symmetrical chiral director for Matteson homologations, is described. It relies on the insertion of lithiated S -2-cyclohexyloxirane into cyclohexylboronic acid pinacol ester and proceeds in three linear steps from readily available starting materials. No step requires chromatography or any specialized equipment.
- Bojaryn, Kevin,Hoffmann, Chris,Struth, Felix R.,Hirschh?user, Christoph
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p. 1092 - 1094
(2018/01/27)
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- METHODS FOR FORMING SATURATED (HETERO)CYCLIC BORYLATED HYDROCARBONS AND RELATED COMPOUNDS
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The disclosure relates to methods for forming at least partially saturated cyclic and heterocyclic borylated hydrocarbons, as well as related compounds, which can be precursor compounds in the synthesis of any of a variety of pharmaceutical or medicinal compounds with a desired structure and/or stereochemistry for drug synthesis or drug candidate evaluation. The methods generally include reduction of an unsaturated cyclic or heterocyclic borylated hydrocarbon having a boron-containing substituent at an sp2-carbon, where such reduction converts the sp2-carbon to an sp3-carbon at the point of attachment of the boron-containing substituent. The methods can exhibit a selectivity for syn-addition during reduction, which can provide stereospecific products, such as when the unsaturated cyclic or heterocyclic reactant is multiply substituted with boron groups and/or other functional groups.
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Paragraph 0065
(2018/03/25)
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- A method for preparing alkyl borate (by machine translation)
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The invention provides a method for preparing alkyl borate, comprises the following steps: formula I - a indicated by the alkyl tosylates and [...][...] as raw materials, in the silver catalyst and under the action of alkali, the reaction is carried out, as shown in formula I alkyl borate. The invention directly by adopting commercial silver salt as a catalyst in the reaction, the reaction system and feeding mode is simple, does not need to add ligand. The use [...][...] alcohol ester of the air and water are not sensitive, in practical application is more convenient. Alkyl tosylates raw material can be conveniently by alkyl alcohol preparation, raw material sources are extensive. At the same time, alkyl tosylates with [...][...] ester by a silver catalyzed direct carbon oxygen key fracture level or secondary alkyl borate, the reaction has good functional group compatibility. (by machine translation)
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Paragraph 0043; 0048; 0050
(2018/03/09)
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- Investigation of the Deprotonative Generation and Borylation of Diamine-Ligated α-Lithiated Carbamates and Benzoates by in Situ IR spectroscopy
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Diamine-mediated α-deprotonation of O-alkyl carbamates or benzoates with alkyllithium reagents, trapping of the carbanion with organoboron compounds, and 1,2-metalate rearrangement of the resulting boronate complex are the primary steps by which organoboron compounds can be stereoselectively homologated. Although the final step can be easily monitored by 11B NMR spectroscopy, the first two steps, which are typically carried out at cryogenic temperatures, are less well understood owing to the requirement for specialized analytical techniques. Investigation of these steps by in situ IR spectroscopy has provided invaluable data for optimizing the homologation reactions of organoboron compounds. Although the deprotonation of benzoates in noncoordinating solvents is faster than that in ethereal solvents, the deprotonation of carbamates shows the opposite trend, a difference that has its origin in the propensity of carbamates to form inactive parasitic complexes with the diamine-ligated alkyllithium reagent. Borylation of bulky diamine-ligated lithiated species in toluene is extremely slow, owing to the requirement for initial complexation of the oxygen atoms of the diol ligand on boron with the lithium ion prior to boron-lithium exchange. However, ethereal solvent, or very small amounts of THF, facilitate precomplexation through initial displacement of the bulky diamines coordinated to the lithium ion. Comparison of the carbonyl stretching frequencies of boronates derived from pinacol boronic esters with those derived from trialkylboranes suggests that the displaced lithium ion is residing on the pinacol oxygen atoms and the benzoate/carbamate carbonyl group, respectively, explaining, at least in part, the faster 1,2-metalate rearrangements of boronates derived from the trialkylboranes.
- Mykura, Rory C.,Veth, Simon,Varela, Ana,Dewis, Lydia,Farndon, Joshua J.,Myers, Eddie L.,Aggarwal, Varinder K.
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supporting information
p. 14677 - 14686
(2018/11/20)
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