916658-71-4Relevant academic research and scientific papers
Selective Benzylic CH-Borylations by Tandem Cobalt Catalysis
Bauer, Matthias,Ghosh, Pradip,Jacobi von Wangelin, Axel,Schoch, Roland
supporting information, (2021/11/27)
Metal-catalyzed C?H activations are environmentally and economically attractive synthetic strategies for the construction of functional molecules as they obviate the need for pre-functionalized substrates and minimize waste generation. Great challenges reside in the control of selectivities, the utilization of unbiased hydrocarbons, and the operation of atom-economical dehydrocoupling mechanisms. An especially mild borylation of benzylic CH bonds was developed with the ligand-free pre-catalyst Co[N(SiMe3)2]2 and the bench-stable and inexpensive borylation reagent B2pin2 that produces H2 as the only by-product. A full set of kinetic, spectroscopic, and preparative mechanistic studies are indicative of a tandem catalysis mechanism of CH-borylation and dehydrocoupling via molecular CoI catalysts.
Catalytic Boration of Alkyl Halides with Borane without Hydrodehalogenation Enabled by Titanium Catalyst
Wang, Xianjin,Cui, Penglei,Xia, Chungu,Wu, Lipeng
supporting information, p. 12298 - 12303 (2021/05/07)
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.
C(sp3)-H selective benzylic borylation by in situ reduced ultrasmall Ni species on CeO2
Yoshii, Daichi,Yatabe, Takafumi,Yabe, Tomohiro,Yamaguchi, Kazuya
, p. 2150 - 2155 (2021/02/20)
Herein, we report that highly dispersed Ni hydroxide species supported on CeO2 act as an efficient heterogeneous catalyst for the selective borylation of benzylic C(sp3)-H bonds of alkylarenes including secondary derivatives, using pinacolborane as the bo
Metal-Free Direct Deoxygenative Borylation of Aldehydes and Ketones
Huang, Chia-Yu,Li, Chao-Jun,Li, Jianbin,Qiu, Zihang,Wang, Haining
supporting information, p. 13011 - 13020 (2020/09/01)
Direct conversion of aldehydes and ketones into alkylboronic esters via deoxygenative borylation represents an unknown yet highly desirable transformation. Herein, we present a one-step and metal-free method for carbonyl deoxy-borylation under mild conditions. A wide range of aromatic aldehydes and ketones are tolerated and successfully converted into the corresponding benzylboronates. By the same deoxygenation manifold with aliphatic aldehydes and ketones, we also enable a concise synthesis of 1,1,2-tris(boronates), a family of compounds that currently lack efficient synthetic methods. Given its simplicity and versatility, we expect that this novel borylation approach could show great promise in organoboron synthesis and inspire more carbonyl deoxygenative transformations in both academic and industrial settings.
Allylboronates from vinyl triflates and α-chloroboronates by reductive nickel catalysis
Qiao, Jin-Bao,Zhao, Zhen-Zhen,Zhang, Ya-Qian,Yin, Kai,Tian, Zhi-Xiong,Shu, Xing-Zhong
supporting information, p. 5085 - 5089 (2020/07/16)
Allylboronates are unique building blocks widely used in organic synthesis, but the construction of cyclic allylboranates remains a challenging subject. We demonstrate here a mild and efficient access to this type of compound through the cross-electrophile coupling of vinyl triflates and α-chloroboronates. The reaction proceeded with a good substrate scope and good functional group compatibility. The ready availability of vinyl triflates from ketones, as well as the rich chemistry of allylboranates, makes our method suitable for the divergent modification of biologically active compounds. Preliminary mechanistic studies revealed that α-chloroboronates were activated via a radical process.
Rapid Access to Highly Functionalized Alkyl Boronates by NiH-Catalyzed Remote Hydroarylation of Boron-Containing Alkenes
Zhang, Yao,Han, Bo,Zhu, Shaolin
supporting information, p. 13860 - 13864 (2019/08/08)
The direct and selective functionalization of relatively simple and readily accessible precursors to produce highly functionalized alkyl boronates is a synthetically useful process. Herein we report a NiH-catalyzed remote hydroarylation process that can, through a synergistic combination of chain walking and subsequent cross-coupling, introduce an aryl group at the adjacent carbon atom of alkyl boronates under mild conditions. By means of a preliminary experiment with moderate enantioselectivity, it was shown that an asymmetric version could also be realized.
Palladium-catalyzed regioselective hydroboration of aryl alkenes with B2pin2
Huang, Jiuzhong,Yan, Wuxin,Tan, Chaowei,Wu, Wanqing,Jiang, Huanfeng
supporting information, p. 1770 - 1773 (2018/02/21)
A palladium(ii)-catalyzed hydroboration of aryl alkenes with stable and easy-to-handle (pinacolato)diboron (B2pin2) under mild conditions has been developed. Acetic acid acted as the solvent and the hydrogen source, which has been identified by deuterium experiments. Notably, isomerization-hydroboration of allyl benzene derivatives was observed. As a result, a series of benzyl boronic esters were obtained in moderate to excellent yields with exclusive regioselectivity.
Markovnikov-Selective Hydroboration of Vinylarenes Catalyzed by a Cobalt(II) Coordination Polymer
Zhang, Guoqi,Wu, Jing,Li, Sihan,Cass, Sean,Zheng, Shengping
supporting information, p. 7893 - 7897 (2019/01/04)
Highly efficient and practical hydroboration of alkenes has been catalyzed by an inexpensive and air-stable cobalt(II) coordination polymer (CP) in the presence of KOtBu. Complete conversion of alkenes to alkylboronates were performed within just 5 min with low catalyst loading (0.025 mol%), achieving the record high turnover frequencies of up to 47 520 h-1. For a range of vinylarenes, unusual Markovnikov selectivity was observed.
Markovnikov-Selective Co(I)-Catalyzed Hydroboration of Vinylarenes and Carbonyl Compounds
Verma, Piyush Kumar,Sethulekshmi,Geetharani
supporting information, p. 7840 - 7845 (2019/01/04)
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
Cobalt-catalysed Markovnikov selective hydroboration of vinylarenes
Peng, Jingying,Docherty, Jamie H.,Dominey, Andrew P.,Thomas, Stephen P.
supporting information, p. 4726 - 4729 (2017/07/10)
A bipyridiyl-oxazoline cobalt catalyst tBuBPOCoCl2 has been developed for the Markovnikov selective hydroboration of alkenes using pinacolborane and NaOtBu as the in situ activator with up to >98 : 2 branched : linear selectivity (24 examples, 45-92% isolated yield).
