94242-85-0Relevant articles and documents
Carbon-carbon bond activation by B(OMe)3/B2pin2-mediated fragmentation borylation
Chen, Quan,Jiang, Jiachen,Wang, Li,Wu, Aizhen,Yin, Youzhi,Zhang, Hua,Zhang, Ke,Zhao, Mengzhen,Zhong, Qi,Zou, Youliang
, p. 15104 - 15109 (2021/12/09)
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
Synthesis of Boroxine and Dioxaborole Covalent Organic Frameworks via Transesterification and Metathesis of Pinacol Boronates
Hamzehpoor, Ehsan,Jonderian, Antranik,McCalla, Eric,Perepichka, Dmitrii F.
supporting information, p. 13274 - 13280 (2021/09/07)
Boroxine and dioxaborole are the first and some of the most studied synthons of covalent organic frameworks (COFs). Despite their wide application in the design of functional COFs over the last 15 years, their synthesis still relies on the original Yaghi's condensation of boronic acids (with itself or with polyfunctional catechols), some of which are difficult to prepare, poorly soluble, or unstable in the presence of water. Here, we propose a new synthetic approach to boroxine COFs (on the basis of the transesterification of pinacol aryl boronates (aryl-Bpins) with methyl boronic acid (MBA) and dioxaborole COFs (through the metathesis of pinacol boronates with MBA-protected catechols). The aryl-Bpin and MBA-protected catechols are easy to purify, highly soluble, and bench-stable. Furthermore, the kinetic analysis of the two model reactions reveals high reversibility (Keq ～1) and facile control over the equilibrium. Unlike the conventional condensation, which forms water as a byproduct, the byproduct of the metathesis (MBA pinacolate) allows for easy kinetic measurements of the COF formation by conventional 1H NMR. We show the generality of this approach by the synthesis of seven known boroxine/dioxaborole COFs whose crystallinity is better or equal to those reported by conventional condensation. We also apply metathesis polymerization to obtain two new COFs, Py4THB and B2HHTP, whose synthesis was previously precluded by the insolubility and hydrolytic instability, respectively, of the boronic acid precursors.
Construction of Silicon-Containing Seven-Membered Rings by Catalytic [4 + 2 + 1] Cycloaddition through Rhodium Silylenoid
Sasaki, Ikuo,Ohmura, Toshimichi,Suginome, Michinori
supporting information, p. 2961 - 2966 (2020/04/10)
A rhodium-catalyzed [4 + 2 + 1] cycloaddition involving 1,3-diene, alkyne, and silylene to afford silicon-containing seven-membered rings was established. In the presence of a rhodium catalyst bearing bis(diphenylphosphino)methane (DPPM), nona-1,3-dien-8-yne derivatives reacted efficiently at 80-110 °C with boryl(isopropoxy)silane or boryl(diethyamino)silane, which reacts as the synthetic equivalent of silylene, to afford 1-silacyclohepta-2,5-dienes (2,5-dihydro-1H-silepines). Regiodivergent and chemo- and stereoselective functionalization of the seven-membered nonconjugated diene was achieved by hydroboration mediated by Cs2CO3 or an iridium catalyst.
Efficient and Selective Methane Borylation Through Pore Size Tuning of Hybrid Porous Organic-Polymer-Based Iridium Catalysts
Chen, Qi,Dong, Anwang,Wang, Dongxu,Qiu, Lu,Ma, Chunxin,Yuan, Yihui,Zhao, Yunpeng,Jia, Na,Guo, Zhanhu,Wang, Ning
supporting information, p. 10671 - 10676 (2019/07/04)
As a new energy source that could replace petroleum, the global reserves of methane hydrate (combustible ice) are estimated to be approximately 20 000 trillion cubic meters. A large amount of methane hydrate has been found under the seabed, but the transportation and storage of methane gas far from coastlines are technically unfeasible and expensive. The direct conversion of methane into value-added chemicals and liquid fuels is highly desirable but remains challenging. Herein, we prepare a series of iridium complexes based on porous polycarbazoles with high specific areas and good thermochemical stabilities. Through structure tuning we optimized their catalytic activities for the selective monoborylation of methane. One of these catalysts (CAL-3-Ir) can produce methyl boronic acid pinacol ester (CH3Bpin) in 29 % yield in 9 h with a turnover frequency (TOF) of approximately 14 h?1. Because its pore sizes favor monoborylated products, it has a high chemoselectivity for monoborylation (CH3Bpin:CH2(Bpin)2=16:1).
Metal-Organic Framework Stabilizes a Low-Coordinate Iridium Complex for Catalytic Methane Borylation
Feng, Xuanyu,Song, Yang,Li, Zhe,Kaufmann, Michael,Pi, Yunhong,Chen, Justin S.,Xu, Ziwan,Li, Zhong,Wang, Cheng,Lin, Wenbin
supporting information, p. 11196 - 11203 (2019/08/07)
Catalytic borylation has recently been suggested as a potential strategy to convert abundant methane to fine chemicals. However, synthetic utility of methane borylation necessitates significant improvement of catalytic activities over original phenanthroline-and diphosphine-Ir complexes. Herein, we report the use of metal-organic frameworks (MOFs) to stabilize low-coordinate Ir complexes for highly active methane borylation to afford the monoborylated product. The mono(phosphine)-Ir based MOF, Zr-P1-Ir, significantly outperformed other Ir catalysts in methane borylation to afford CH3Bpin with a turnover number of 127 at 110 °C. Density functional theory calculations indicated a significant reduction of activation barrier for the rate limiting oxidative addition of methane to the four-coordinate (P1)IrIII(Bpin)3 catalyst to form the six-coordinate (P1)IrV(Bpin)3(CH3)(H) intermediate, thus avoiding the formation of sterically encumbered seven-coordinate IrV intermediates as found in other Ir catalysts based on chelating phenanthroline, bipyridine, and diphosphine ligands. MOF thus stabilizes the homogeneously inaccessible, low-coordinate (P1)Ir(boryl)3 catalyst to provide a unique strategy to significantly lower the activation barrier for methane borylation. This MOF-based catalyst design holds promise in addressing challenging catalytic reactions involving highly inert substrates.
Catalyst-controlled selectivity in the C-H borylation of methane and ethane
Cook, Amanda K.,Schimler, Sydonie D.,Matzger, Adam J.,Sanford, Melanie S.
, p. 1421 - 1424 (2016/04/05)
The C-H bonds of methane are generally more kinetically inert than those of other hydrocarbons, reaction solvents, and methane functionalization products.Thus, developing strategies to achieve selective functionalization of CH4 remains a major
Metal-Organic Framework Nodes Support Single-Site Magnesium-Alkyl Catalysts for Hydroboration and Hydroamination Reactions
Manna, Kuntal,Ji, Pengfei,Greene, Francis X.,Lin, Wenbin
supporting information, p. 7488 - 7491 (2016/07/06)
Here we present the first example of a single-site main group catalyst stabilized by a metal-organic framework (MOF) for organic transformations. The straightforward metalation of the secondary building units of a Zr-MOF with Me2Mg affords a hi
Aluminum Hydride Catalyzed Hydroboration of Alkynes
Bismuto, Alessandro,Thomas, Stephen P.,Cowley, Michael J.
supporting information, p. 15356 - 15359 (2016/12/06)
An aluminum-catalyzed hydroboration of alkynes using either the commercially available aluminum hydride DIBAL-H or bench-stable Et3Al?DABCO as the catalyst and H-Bpin as both the boron reagent and stoichiometric hydride source has been developed. Mechanistic studies revealed a unique mode of reactivity in which the reaction is proposed to proceed through hydroalumination and σ-bond metathesis between the resultant alkenyl aluminum species and HBpin, which acts to drive turnover of the catalytic cycle.
Catalytic borylation of methane
Smith, Kyle T.,Berritt, Simon,González-Moreiras, Mariano,Ahn, Seihwan,Smith, Milton R.,Baik, Mu-Hyun,Mindiola, Daniel J.
, p. 1424 - 1427 (2016/04/05)
Despite steady progress in catalytic methods for the borylation of hydrocarbons, methane has not yet been subject to this transformation. Here we report the iridium-catalyzed borylation of methane using bis(pinacolborane) in cyclohexane solvent. Initially, trace amounts of borylated products were detected with phenanthroline-coordinated Ir complexes. A combination of experimental high-pressure and high-throughput screening, and computational mechanism discovery techniques helped to rationalize the foundation of the catalysis and identify improved phosphine-coordinated catalytic complexes. Optimized conditions of 150°C and 3500-kilopascal pressure led to yields as high as ～52%, turnover numbers of 100, and improved chemoselectivity for monoborylated versus diborylated methane.
