- 1,2-Boron Shifts of β-Boryl Radicals Generated from Bis-boronic Esters Using Photoredox Catalysis
-
1,2-Bis-boronic esters are versatile intermediates that enable the rapid elaboration of simple alkene precursors. Previous reports on their selective mono-functionalization have targeted the most accessible position, retaining the more hindered secondary boronic ester. In contrast, we have found that photoredox-catalyzed mono-deboronation generates primary β-boryl radicals that undergo rapid 1,2-boron shift to form thermodynamically favored secondary radicals, allowing for selective transformation of the more hindered boronic ester. The pivotal 1,2-boron shift, which has been demonstrated to be stereoretentive, enables access to a wide range of functionalized boronic esters and has been applied to highly diastereoselective fragmentation and transannular cyclization reactions. Furthermore, its generality has been shown in a radical cascade reaction with an allylboronic ester.
- Kaiser, Daniel,Noble, Adam,Fasano, Valerio,Aggarwal, Varinder K.
-
-
Read Online
- Reaction mechanism of the anomalous formal nucleophilic borylation of organic halides with silylborane: Combined theoretical and experimental studies
-
Theoretical and experimental studies have been conducted to elucidate the mechanism of the formal nucleophilic boryl substitution of aryl and alkyl bromides with silylborane in the presence of potassium methoxide. Density functional theory was used in conjunction with the artificial force induced reaction method in the current study to determine the mechanism of this reaction. The results of this analysis led to the identification of a unique carbanion-mediated mechanism involving the halogenophilic attack of a silyl nucleophile on the bromine atom of the substrate. These calculations have, therefore, provided a mechanistic rationale for this counterintuitive borylation reaction. Furthermore, the good functional group compatibility and high reactivity exhibited by this reaction toward sterically hindered substrates can be understood in terms of the low activation energy required for the reaction of the silyl nucleophile with the bromine atom of the substrate and the subsequent rapid and selective consumption of the carbanion species by the in situ generated boron electrophile. The results of an experimental study involving the capture of the anion intermediate provided further evidence in support of the generation of a carbanion species during the course of this reaction. The anomalous formal nucleophilic borylation mechanism reported in this study could be used to provide new insights into silicon and boron chemistry.
- Uematsu, Ryohei,Yamamoto, Eiji,Maeda, Satoshi,Ito, Hajime,Taketsugu, Tetsuya
-
-
Read Online
- Palladium-catalyzed benzylic C-H borylation of alkylbenzenes with bis(pinacolato)diboron or pinacolborane
-
Borylation at the benzylic C-H bond of alkylbenzenes with bis(pinacolato)diboron [(Me4C2O2)B-B(O2C2Me 4)] or pinacolborane [(Me4C2O2)B-H] was carried out at
- Ishiyama, Tatsuo,Ishida, Kousaku,Takagi, Jun,Miyaura, Norio
-
-
Read Online
- Bimetallic Cu(i) complex with a pyridine-bridged bis(1,2,3-triazole-5-ylidene) ligand
-
A dinuclear copper(i) complex bearing a mesoionic carbene ligand has been prepared from the corresponding silver analogue and its structure determined spectroscopically. The results revealed that two Cu(i) halide salt molecules were bound to the carbon at
- Iwasaki, Haruka,Teshima, Yuta,Yamada, Yuji,Ishikawa, Ryuta,Koga, Yuji,Matsubara, Kouki
-
-
Read Online
- Rh(I)-catalyzed borylation of primary alkyl chlorides
-
Rhodium-catalyzed cross-coupling reactions of unactivated primary alkyl chlorides with diboron reagents have been developed as practical methods for the synthesis of alkylboronic esters. These reactions expand the concept and utility of Rh(I)-catalyzed cr
- Gong, Tian-Jun,Jiang, Yuan-Ye,Fu, Yao
-
-
Read Online
- Hierarchical hybrid MnO/Pd-Fe3O4 and CoO/Pd-Fe3O4 nanocomposites as efficient catalysts for hydroboration of styrene
-
We report a one-pot synthesis of hierarchical MnO/Pd-Fe3O4 and CoO/Pd-Fe3O4 nanocomposites containing scrolled multilayered nanosheets by controlled thermal decomposition of Fe(CO)5 and reduction of metal precursors [Pd(OAc)2]. During the synthetic process, particles of amorphous MnO and CoO are immobilized on the Pd-Fe3O4 support. These hierarchical nanocomposites follow a stepwise growth mechanism, initially forming Pd-Fe3O4 seeds aggregated from nuclei, followed by growth to produce multilayered MnO/Pd-Fe3O4 or CoO/Pd-Fe3O4 structures. To the best of our knowledge, this is the first report on the hydroboration of styrene with bis(pinacolato)diboron using heterogeneous nanocatalysts. Among these catalysts, CoO/Pd-Fe3O4 nanocomposites showed excellent performance due to the presence of a dual Pd and CoO catalytic system.
- Woo, Hyunje,Park, Junha,Kim, Jiwoong,Park, Sungkyun,Park, Kang Hyun
-
-
Read Online
- Fundamental organometallic chemistry under bimetallic influence: Driving β-hydride elimination and diverting migratory insertion at Cu and Ni
-
Bimetallic effects on stoichiometric β-hydride elimination and migratory insertion reactions were examined. Bimetallic reaction conditions drove β-hydride elimination at Cu, while bimetallic C-B elimination occurred in the absence of β-hydrogens. The inhe
- Mazzacano, Thomas J.,Leon, Noel J.,Waldhart, Greyson W.,Mankad, Neal P.
-
-
Read Online
- Structure and reactivity of a copper(I)-fused N-heterocyclic carbene complex: Reactivity toward styrenic and strained alkenes
-
The synthesis of a fused N-heterocyclic carbene complex is accomplished using a flow-chemistry approach where a fused N-herterocyclic imidazolium chloride is passed through a packed bed of copper(I) oxide. The identity of the resulting complex is confirmed via crystal structure, and the reactivity is examined in the context of alkene hydroboration. We demonstrate that this novel complex can perform the desired reaction whereas the carbene ligand alone cannot. Georg Thieme Verlag Stuttgart New York.
- Ondrusek, Brian A.,Opalka, Suzanne M.,Hietsoi, Oleksandr,Shatruk, Michael,McQuade, D. Tyler
-
-
Read Online
- Borohydrogenation reaction method of halide calcium catalyzed olefins
-
The present invention discloses a method of borohydrogenation of olefins catalyzed by calcium halide, comprising, under anhydrous and anaerobic conditions, calcium halide added to the mixture of olefins and pinacol borane, stirred at 90 to 110 ° C for 6 t
- -
-
Paragraph 0024-0029
(2022/01/12)
-
- Neosilyllithium-Catalyzed Hydroboration of Alkynes and Alkenes in the Presence of Pinacolborane (HBpin)
-
We report here a novel protocol for the hydroboration of alkynes and alkenes, which in the presence of neosilyllithium (LiCH2SiMe3) (5 mol %) and pinacolborane efficiently results in the formation of corresponding alkenyl and alkyl b
- Kumar, Gobbilla Sai,Moorthy, Shruti,Karmakar, Himadri,Singh, Saurabh Kumar,Panda, Tarun K.
-
supporting information
(2021/11/13)
-
- Nickel-Catalyzed Enantioselective Hydroboration of Vinylarenes
-
The enantioselective hydroboration of vinylarenes catalyzed by a chiral, nonracemic nickel catalyst is presented as a facile method for generating chiral benzylic boronate esters. Various vinylarenes react with bis(pinacolato)diboron (B2pin2) in the presence of MeOH as a hydride source to form chiral boronate esters in up to 92% yield with up to 94% ee. The use of anhydrous Me4NF to activate B2pin2 is crucial for ensuring fast transmetalation to achieve high enantioselectivities.
- Tran, Hai N.,Stanley, Levi M.
-
supporting information
p. 395 - 399
(2021/12/27)
-
- 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
-
supporting information
p. 487 - 492
(2021/12/06)
-
- Tropylium-Promoted Hydroboration Reactions: Mechanistic Insights Via Experimental and Computational Studies
-
Hydroboration reaction of alkynes is one of the most synthetically powerful tools to access organoboron compounds, versatile precursors for cross-coupling chemistry. This type of reaction has traditionally been mediated by transition-metal or main group catalysts. Herein, we report a novel method using tropylium salts, typically known as organic oxidants and Lewis acids, to promote the hydroboration reaction of alkynes. A broad range of vinylboranes can be easily accessed via this metal-free protocol. Similar hydroboration reactions of alkenes and epoxides can also be efficiently catalyzed by the same tropylium catalysts. Experimental studies and DFT calculations suggested that the reaction follows an uncommon mechanistic pathway, which is triggered by the hydride abstraction of pinacolborane with tropylium ion. This is followed by a series ofin situcounterion-activated substituent exchanges to generate boron intermediates that promote the hydroboration reaction.
- Ton, Nhan N. H.,Mai, Binh Khanh,Nguyen, Thanh Vinh
-
p. 9117 - 9133
(2021/07/19)
-
- 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
-
p. 258 - 265
(2021/02/16)
-
- Copper-Photocatalyzed Hydroboration of Alkynes and Alkenes
-
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
-
supporting information
p. 14498 - 14503
(2021/05/21)
-
- Recyclable Copper Nanoparticles-Catalyzed Hydroboration of Alkenes and β-Borylation of α,β-Unsaturated Carbonyl Compounds with Bis(Pinacolato)Diboron
-
Nano-ferrite-supported Cu nanoparticles (Fe-dopamine-Cu NPs) catalyzed anti-Markovnikov-selective hydroboration of alkenes with B2pin2 is reported under mild reaction conditions. This protocol can be applied to a broad range of substrates with high functional group compatibility. In addition, we demonstrated the use of Fe-dopamine-Cu NPs as a catalyst for the β-borylation of α,β-unsaturated ketones and ester, providing alkylboronate esters in up to 98% yield. Reuse of the magnetically recyclable catalyst resulted in no significant loss of activity in up to five reaction runs for both systems. (Figure presented.).
- Shegavi, Mahadev L.,Saini, Suresh,Bhawar, Ramesh,Vishwantha, Meghana Desai,Bose, Shubhankar Kumar
-
supporting information
p. 2408 - 2416
(2021/03/16)
-
- Rhodium-Catalyzed Regiodivergent Synthesis of Alkylboronates via Deoxygenative Hydroboration of Aryl Ketones: Mechanism and Origin of Selectivities
-
Here, we report an efficient rhodium-catalyzed deoxygenative borylation of ketones to synthesize alkylboronates, in which the regioselectivity can be switched by the choice of the ligand. The linear alkylboronates were obtained exclusively in the presence of P(nBu)3, and PPh2Me favored the formation of branched alkylboronates. The protocol also allows access to 1,1,2-triboronates from the readily available ketones. Mechanistic studies suggest that this Rh-catalyzed deoxygenative borylation of ketones goes through an alkene intermediate, which undergoes regiodivergent hydroboration to afford linear and branched alkylboronates. The different steric effects of PPh2Me and P(nBu)3 were found to be responsible for product selectivity by density functional theory calculations. The alkene intermediate can alternatively undergo sequential dehydrogenative borylation and hydroboration to deliver the triboronates.
- Zhang, Bing,Xu, Xin,Tao, Lei,Lin, Zhenyang,Zhao, Wanxiang
-
p. 9495 - 9505
(2021/08/04)
-
- Site-Fixed Hydroboration of Terminal and Internal Alkenes using BX3/iPr2NEt**
-
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
-
p. 26238 - 26245
(2021/11/09)
-
- Light-Mediated Sulfur-Boron Exchange
-
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.
-
supporting information
p. 3919 - 3922
(2021/05/29)
-
- Highly Selective Hydroboration of Terminal Alkenes Catalyzed by a Cobalt Pincer Complex Featuring a Central Reactive N-Heterocyclic Phosphido Fragment
-
The application of a cobalt pincer complex, (PPClP)CoCl2, as a precatalyst for the hydroboration of terminal alkenes with pinacolborane (HBPin) is described. The reactions proceed rapidly under mild conditions (room temperature, 30 min) with low catalyst
- Poitras, Andrew M.,Oliemuller, Leah K.,Hatzis, Gregory P.,Thomas, Christine M.
-
supporting information
p. 1025 - 1031
(2021/05/07)
-
- Silver-Catalyzed Hydroboration of C-X (X = C, O, N) Multiple Bonds
-
AgSbF6 was developed as an effective catalyst for the hydroboration of various unsaturated functionalities (nitriles, alkenes, and aldehydes). This atom-economic chemoselective protocol works effectively under low catalyst loading, base- A nd solvent-free moderate conditions. Importantly, this process shows excellent functional group tolerance and compatibility with structurally and electronically diverse substrates (>50 examples). Mechanistic investigations revealed that the reaction proceeds via a radical pathway. Further, the obtained N,N-diborylamines were showcased to be useful precursors for amide synthesis.
- Pandey, Vipin K.,Tiwari, Chandra Shekhar,Rit, Arnab
-
supporting information
p. 1681 - 1686
(2021/03/03)
-
- Matteson Reaction under Flow Conditions: Iterative Homologations of Terpenes
-
The Matteson reaction is ideally suited for flow chemistry since it allows iterative homologation of boronate esters. The present study provides accurate data on reaction times of the individual steps of the Matteson reaction, which occurs in less than 10 s in total. The protocol allows terpenes to be (per-)homologated in a controlled manner to yield homo-, bishomo-, and trishomo-terpenols after oxidative workup. The new terpene alcohols are validated with respect to their olfactoric properties.
- Kuhwald, Conrad,Kirschning, Andreas
-
supporting information
p. 4300 - 4304
(2021/05/26)
-
- Zwitterion-Initiated Hydroboration of Alkynes and Styrene
-
The hydroboration of alkynes and styrene with HBpin has been developed using tris(pentaflurophenyl)borane (B(C6F5)3) as the initiator of catalysis. The hydroboration is proposed to be initiated by Lewis acid activation of the alkyne by (B(C6F5)3) to form a highly reactive zwitterionic species which subsequently react with HBpin to give the alkenyl boronic ester. This zwitterion has also showed potential to be a competent catalyst for the hydroboration of styrene. The zwitterionic intermediate is analogous to that proposed in the Piers borane-catalysed hydroboration and 1,1-carboboration of alkynes with B(C6F5)3. (Figure presented.).
- Bismuto, Alessandro,Cowley, Michael J.,Thomas, Stephen P.
-
supporting information
p. 2382 - 2385
(2021/01/18)
-
- Manganese-Catalyzed Hydroboration of Terminal Olefins and Metal-Dependent Selectivity in Internal Olefin Isomerization-Hydroboration
-
In the past decade, the use of earth-abundant metals in homogeneous catalysis has flourished. In particular, metals such as cobalt and iron have been used extensively in reductive transformations including hydrogenation, hydroboration, and hydrosilylation
- Garhwal, Subhash,Kroeger, Asja A.,Thenarukandiyil, Ranjeesh,Fridman, Natalia,Karton, Amir,De Ruiter, Graham
-
supporting information
p. 494 - 504
(2021/01/11)
-
- Synthesis and Catalytic Reactivity of Cobalt Pincer Nitrosyl Hydride Complexes
-
The synthesis, characterization, and catalytic activity of low-spin {CoNO}8 pincer complexes of the type [Co(PCP)(NO)(H)] are described. These compounds are obtained either by reacting [Co(PCP)(κ2-BH4)] with NO and Et3N or, alternatively, by reacting [Co(
- Pecak, Jan,Fleissner, Sarah,Veiros, Luis F.,Pittenauer, Ernst,St?ger, Berthold,Kirchner, Karl
-
p. 278 - 285
(2021/02/03)
-
- Selective hydroboration of equilibrating allylic azides
-
The iridium(i)-catalyzed hydroboration of equilibrating allylic azides is reported to provide only the anti-Markovnikov product of alk-1-ene isomers in good yields and with good functional group tolerance.
- Liu, Ruzhang,Xu, Jun,Zhang, Yuanyuan
-
supporting information
p. 8913 - 8916
(2021/09/13)
-
- Hydroboration of Terminal Alkenes and trans-1,2-Diboration of Terminal Alkynes Catalyzed by a Manganese(I) Alkyl Complex
-
A MnI-catalyzed hydroboration of terminal alkenes and a 1,2-diboration of terminal alkynes with pinacolborane (HBPin) is described. For alkenes, anti-Markovnikov hydroboration takes place; for alkynes the reaction proceeds with excellent trans-1,2-selectivity. The most active pre-catalyst is bench-stable alkyl bisphosphine MnI complex fac-[Mn(dippe)(CO)3(CH2CH2CH3)]. The catalytic process is initiated by migratory insertion of a CO ligand into the Mn–alkyl bond to yield an acyl intermediate, which undergoes B?H bond cleavage of HBPin (for alkenes) and rapid C?H bond cleavage (for alkynes), forming the active MnI boryl and acetylide catalysts [Mn(dippe)(CO)2(BPin)] and [Mn(dippe)(CO)2(C≡CR)], respectively. A broad variety of aromatic and aliphatic alkenes and alkynes was efficiently and selectively borylated. Mechanistic insights are provided based on experimental data and DFT calculations revealing that an acceptorless reaction is operating involving dihydrogen release.
- Kirchner, Karl,St?ger, Berthold,Veiros, Luis F.,Weber, Stefan,Zobernig, Daniel
-
supporting information
p. 24488 - 24492
(2021/10/19)
-
- Pyridylpyrrolido ligand in Ge(ii) and Sn(ii) chemistry: Synthesis, reactivity and catalytic application
-
In our previous communication, we have reported the synthesis of a new chlorogermylene (B) featuring a pyridylpyrrolido ligand. This study details the preparation of a series of new germylenes and stannylenes starting from B. A transmetallation reaction between B and SnCl2 led to the analogous chlorostannylene (1) with the simultaneous elimination of GeCl2. This is a very unusual example of transmetallation between two elements of the same group. The preparation of 1via lithiation led to the formation of 2 as a side product, where the ortho C-H bond of the pyridine ring was activated and functionalized with a nBu moiety. Subsequently, B and 1 were used as precursors to generate germylene (4) and stannylene (5) featuring tris(trimethylsilyl)silyl (hypersilyl) moieties. We also prepared tetrafluoropyridyl germylene (6) by reacting 4 with C5F5N with the simultaneous elimination of (Me3Si)3SiF by utilizing the fluoride affinity of the silicon atom. As there is scarcity of Sn(ii) compounds as single-site catalysts, we investigated 5 as a catalyst towards the hydroboration of aldehydes, ketones, alkenes and alkynes. All the compounds have been characterized by single-crystal X-ray diffraction and by state of the art spectroscopic studies.
- Pahar, Sanjukta,Sen, Sakya S.,Sharma, Vishal,Tothadi, Srinu
-
supporting information
p. 16678 - 16684
(2021/12/07)
-
- Evaluation of the role of graphene-based Cu(i) catalysts in borylation reactions
-
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
-
p. 3501 - 3513
(2021/06/06)
-
- Method for directly preparing alkyl borate compound from alkyl halide
-
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 0250-0252
(2021/04/14)
-
- 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)
-
- 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
-
supporting information
p. 2204 - 2208
(2021/06/28)
-
- Selective electrocatalytic hydroboration of aryl alkenes
-
Organoboron compounds are powerful precursors of value-added organic compounds in synthetic chemistry, and transition metal-catalysed borylation has always been dominant. To avoid toxic reagents and costs associated with metal catalysts, simpler, more eco
- Zhang, Yahui,Zhao, Xiangyu,Bi, Ce,Lu, Wenqi,Song, Mengyuan,Wang, Dongdong,Qing, Guangyan
-
supporting information
p. 1691 - 1699
(2021/03/09)
-
- (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)
-
- Arene borylation through C–H activation using Cu3(BTC)2 as heterogeneous catalyst
-
C–H borylation by diborane is an important process to access organoboron compounds. Noble metals, including Ir and Rh-based complexes either in the form of homogeneous or heterogeneous catalysts, have been reported to promote arene C–H borylation. Recently, metal organic frameworks (MOFs) having Ir and Co as active sites have been used as catalysts, but they require co-catalysts. In the present study, commercially available Cu3(BTC)2 (BTC: 1,3,5-benzenetricarboxylate) MOF is reported as an effective catalyst to promote borylation of arenes through C–H activation employing bis(pinacolato)diboron (1) as reagent leading to benzylic and aromatic borylation products. Interestingly, other related MOFs like MIL-101(Cr) and Al(OH)(BDC) (BDC: 1,4-benzenedicarboxylate) do not exhibit catalytic activity under identical conditions. Mechanistic studies using in-situ IR spectroscopy reveal that Cu ions play a crucial role in activating the arene and B–B bond in 1.
- Dhakshinamoorthy, Amarajothi,García, Cristina Vallés,Concepcion, Patricia,Garcia, Hermenegildo
-
p. 212 - 217
(2020/07/06)
-
- 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
-
supporting information
p. 12985 - 12991
(2021/09/03)
-
- 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
-
-
- Ring-Opening Lithiation–Borylation of 2-Trifluoromethyl Oxirane: A Route to Versatile Tertiary Trifluoromethyl Boronic Esters
-
Stereogenic trifluoromethyl-substituted carbon centers are highly sought-after moieties in pharmaceutical and agrochemical discovery. Here, we show that lithiation–borylation reactions of 2-trifluoromethyl oxirane give densely functionalized and highly versatile trifluoromethyl-substituted α-tertiary boronic esters. The intermediate boronate complexes undergo the desired 1,2-rearrangement of the carbon-based group with complete retentive stereospecificity, a process that was only observed in non-polar solvents in the presence of TESOTf. Although the trifluoromethyl group adversely affects subsequent transformations of the α-boryl group, Zweifel olefinations provide trifluoromethyl-bearing quaternary stereocenters substituted with alkenes, alkynes and ketones.
- Nandakumar, Meganathan,Rubial, Belén,Noble, Adam,Myers, Eddie L.,Aggarwal, Varinder K.
-
supporting information
p. 1187 - 1191
(2019/12/15)
-
- Hydroboration of Alkenes Catalysed by a Nickel N-Heterocyclic Carbene Complex: Reaction and Mechanistic Aspects
-
The pentamethylcyclopentadienyl N-heterocyclic carbene nickel complex [Ni(η5-C5Me5)Cl(IMes)] (IMes=1,3-dimesitylimidazol-2-ylidene) efficiently catalyses the anti-Markovnikov hydroboration of alkenes with catecholborane in
- Chetcuti, Michael J.,Cornaton, Yann,Djukic, Jean-Pierre,Ritleng, Vincent,Ulm, Franck
-
-
- Zirconium-Catalyzed Atom-Economical Synthesis of 1,1-Diborylalkanes from Terminal and Internal Alkenes
-
A general and atom-economical synthesis of 1,1-diborylalkanes from alkenes and a borane without the need for an additional H2 acceptor is reported for the first time. The key to our success is the use of an earth-abundant zirconium-based catalyst, which allows a balance of self-contradictory reactivities (dehydrogenative boration and hydroboration) to be achieved. Our method avoids using an excess amount of another alkene as an H2 acceptor, which was required in other reported systems. Furthermore, substrates such as simple long-chain aliphatic alkenes that did not react before also underwent 1,1-diboration in our system. Significantly, the unprecedented 1,1-diboration of internal alkenes enabled the preparation of 1,1-diborylalkanes.
- Cui, Xin,Jiao, Haijun,Li, Sida,Wang, Xianjin,Wang, Yue,Wu, Lipeng,Xia, Chungu
-
supporting information
p. 13608 - 13612
(2020/06/02)
-
- A General Approach to Deboronative Radical Chain Reactions with Pinacol Alkylboronic Esters
-
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.
-
supporting information
p. 13859 - 13864
(2020/06/10)
-
- Aluminum-Catalyzed Selective Hydroboration of Nitriles and Alkynes: A Multifunctional Catalyst
-
The reaction of LH [L = {(ArNH)(ArN)-C=N-C=(NAr)(NHAr)}; Ar =2,6-Et2-C6H3] with a commercially available alane amine adduct (H3Al·NMe2Et) in toluene resulted in the formation of a conjugated bis-guanidinate (CBG)-supported aluminum dihydride complex, i.e., LAlH2 (1), in good yield. The new complex has been thoroughly characterized by multinuclear magnetic resonance, IR, mass, and elemental analyses, including single-crystal structural studies. Further, we have demonstrated the aluminum-catalyzed hydroboration of a variety of nitriles and alkynes. Moreover, aluminum-catalyzed hydroboration is expanded to more challenging substrates such as alkene, pyridine, imine, carbodiimide, and isocyanides. More importantly, we have shown that the aluminum dihydride catalyzed both intra- A nd intermolecular chemoselective hydroboration of nitriles and alkynes over other reducible functionalities for the first time.
- Sarkar, Nabin,Bera, Subhadeep,Nembenna, Sharanappa
-
p. 4999 - 5009
(2020/05/01)
-
- Aminoazanium of DABCO: An Amination Reagent for Alkyl and Aryl Pinacol Boronates
-
The aminoazanium of DABCO (H2N-DABCO) has been developed as a general and practical amination reagent for the direct amination of alkyl and aryl pinacol boronates. This compound is stable and practical for use as a reagent. Various primary, secondary. and tertiary alkyl?Bpin and aryl?Bpin substrates were aminated to give the corresponding amine derivatives. The amination is stereospecific. The anti-Markovnikov hydroamination of olefins was easily achieved by catalytic hydroboration with HBpin and in subsequent situ amination using H2N-DABCO. Moreover, the combination of 1,2-diboration of olefins, using B2pin2, with this amination process achieved the unprecedented 1,2-diamination of olefins. The amination protocol was also successfully extended to aryl pinacol boronates.
- Liu, Xingxing,Zhu, Qing,Chen, Du,Wang, Lu,Jin, Liqun,Liu, Chao
-
supporting information
p. 2745 - 2749
(2020/01/25)
-
- Rhodium-Catalyzed Deoxygenation and Borylation of Ketones: A Combined Experimental and Theoretical Investigation
-
The rhodium-catalyzed deoxygenation and borylation of ketones with B2pin2 have been developed, leading to efficient formation of alkenes, vinylboronates, and vinyldiboronates. These reactions feature mild reaction conditions, a broad substrate scope, and excellent functional-group compatibility. Mechanistic studies support that the ketones initially undergo a Rh-catalyzed deoxygenation to give alkenes via boron enolate intermediates, and the subsequent Rh-catalyzed dehydrogenative borylation of alkenes leads to the formation of vinylboronates and diboration products, which is also supported by density functional theory calculations.
- Tao, Lei,Guo, Xueying,Li, Jie,Li, Ruoling,Lin, Zhenyang,Zhao, Wanxiang
-
supporting information
p. 18118 - 18127
(2020/11/26)
-
- Synthesis of stereodefined 1,1-diborylalkenes via copper-catalyzed diboration of terminal alkynes
-
A copper-catalyzed method for the E-selective 1,1-diboration of terminal alkynes is described. The tandem process involves sequential dehydrogenative borylation of the alkyne substrate with HBdan (1,8-diaminonaphthalatoborane), followed by hydroboration w
- Engle, Keary M.,Gao, Yang,Wu, Zhong-Qian
-
supporting information
(2020/07/14)
-
- 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)
-
- Bisoxazoline-pincer ligated cobalt-catalyzed hydrogenation of alkenes
-
The efficient and atom economical hydrogenation of alkenes using a novel bisoxazoline ligated cobalt complex has been developed. The hydrogenation of a variety of alkenes containing electron neutral and electron-donating groups proceeds in high yield, whi
- Ritz, Mikhaila D.,Parsons, Astrid M.,Palermo, Philip N.,Jones, William D.
-
supporting information
(2020/02/13)
-
- 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
-
supporting information
p. 1431 - 1436
(2020/03/13)
-
- 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
-
supporting information
p. 2799 - 2803
(2020/06/17)
-
- 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)
-
- Complex Boron-Containing Molecules through a 1,2-Metalate Rearrangement/anti-SN2′ Elimination/Cycloaddition Reaction Sequence
-
The three-component coupling of benzylamines, boronic esters, and 4-phenyl-3 H -1,2,4-triazole-3,5(4 H)-dione (PTAD) is reported. The boronate complex formed from an ortho -lithiated benzylamine and a boronic ester undergoes a stereospecific 1,2-metalate rearrangement/ anti -S N 2′ elimination in the presence of an N-activator to provide a dearomatized tertiary boronic ester. Interception of this dearomatized intermediate with a dienophile leads to stereopredictable cycloaddition reactions to generate highly complex three-dimensional boron-containing molecular structures. When enantioenriched α-methyl-substituted benzylamines are employed, the corresponding cycloaddition adducts are formed with excellent enantiospecificities.
- Tillin, Chloe,Bigler, Raphael,Calo-Lapido, Renata,Collins, Beatrice S.L.,Noble, Adam,Aggarwal, Varinder K.
-
supporting information
p. 449 - 453
(2019/02/26)
-
- Aluminum-Catalyzed Selective Hydroboration of Alkenes and Alkynylsilanes
-
An efficient aluminum-catalyzed selective hydroboration of alkenes and alkynylsilanes is reported. A wide variety of alkenes and alkynylsilanes bearing various functional groups and heterocyclic substituents were converted to boronic ester products in goo
- Li, Feng,Bai, Xu,Cai, Yuan,Li, Han,Zhang, Shuo-Qing,Liu, Feng-Hua,Hong, Xin,Xu, Youjun,Shi, Shi-Liang
-
supporting information
p. 1703 - 1708
(2019/09/04)
-
- Hydroboration of terminal olefins with pinacolborane catalyzed by new 2-iminopyrrolyl iron(ii) complexes
-
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.
-
p. 3347 - 3360
(2019/07/10)
-
- Redox switchable catalysis utilizing a fluorescent dye
-
This report describes the implementation of a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye into the ligand framework of a Rh-based catalyst. The redox-active nature of the BODIPY dye is utilized to generate a catalyst that is capable of exhibit
- Heiden, Zachariah M.,Simons, Casey R.,Thompson, Brena L.
-
supporting information
p. 11430 - 11433
(2019/09/30)
-
- Stereoselective Alkyne Hydrogenation by using a Simple Iron Catalyst
-
The stereoselective hydrogenation of alkynes constitutes one of the key approaches for the construction of stereodefined alkenes. The majority of conventional methods utilize noble and toxic metal catalysts. This study concerns a simple catalyst comprised of the commercial chemicals iron(II) acetylacetonate and diisobutylaluminum hydride, which enables the Z-selective semihydrogenation of alkynes under near ambient conditions (1–3 bar H2, 30 °C, 5 mol % [Fe]). Neither an elaborate catalyst preparation nor addition of ligands is required. Mechanistic studies (kinetic poisoning, X-ray absorption spectroscopy, TEM) strongly indicate the operation of small iron clusters and particle catalysts.
- Gregori, Bernhard J.,Schwarzhuber, Felix,P?llath, Simon,Zweck, Josef,Fritsch, Lorena,Schoch, Roland,Bauer, Matthias,Jacobi von Wangelin, Axel
-
p. 3864 - 3870
(2019/07/31)
-
- Remote coordination approach for electronic tuning of a rhodium(I)-N-heterocyclic carbene (NHC)-complex
-
A simple Lewis acid coordination at the remote binding site installed within a modular N-heterocyclic carbene (NHC) ligated rhodium(I) complex could induce desired electronic influence and thereby enhance the activity of the complex in a model styrene hyd
- Thenarukandiyil, Ranjeesh,Maji, Babulal,Choudhury, Joyanta
-
p. 419 - 423
(2019/01/08)
-
- Method for catalytic synthesis of borate derivatives by non-transition metal
-
The invention relates to a method for catalytic synthesis of borate derivatives by a non-transition metal, and belongs to the technical field of borate compound synthesis. The method comprises the following steps: performing a reaction under stirring and
- -
-
Paragraph 0053; 0062-0065
(2020/01/03)
-