- Ag(I)-catalyzed C-H borylation of terminal alkynes
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An efficient Ag(I)-catalyzed borylation method of terminal alkynes is reported. The obtained borylated alkynes are shown to engage in C-Br, C-CN, C-N, and C-C bond formation with various reaction partners. Meanwhile the Ag(I) catalyst could be regenerated in the presence of PPh3 and BF3.
- Hu, Jiu-Rong,Liu, Lin-Hai,Hu, Xin,Ye, Hong-De
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- ZnBr2-Catalyzed Dehydrogenative Borylation of Terminal Alkynes
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The simple, commercially available ZnBr2 has been successfully employed as a highly efficient and chemoselective catalyst for the dehydrogenative borylation of terminal alkynes with HBpin under mild conditions. It shows a good tolerance toward various functional groups such as aryl, alkyl, heteroaryl, etc. The plausible reaction mechanism has been investigated based on the corresponding stoichiometric experiments and DFT calculations.
- Luo, Man,Qin, Yi,Chen, Xi,Xiao, Qian,Zhao, Binlin,Yao, Weiwei,Ma, Mengtao
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p. 16666 - 16674
(2021/11/18)
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- Method for removing hydroboration of aluminum chloride catalytic terminal group alkyne
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The invention discloses a hydroboration method of an aluminum chloride catalytic terminal group alkyne, and belongs to the technical field of boronation of terminal alkynes. To the method, the terminal group alkyne is added into the aluminum chloride with
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Paragraph 0043-0045
(2021/10/16)
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- Boron Recycling in the Metal-Free Transfer C-H Borylation of Terminal Alkynes and Heteroarenes
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Transfer C-H borylation is an isodesmic approach to the borylation reaction using B-C-containing molecules as boron sources. In this work, we report that 2-mercaptothiazole and other analogues are active for the metal-free borylation of heterocycles and t
- Desrosiers, Vincent,Fontaine, Frédéric-Georges,Garcia, Cecilia Zavaleta
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p. 11046 - 11056
(2020/11/23)
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- Ru-Catalyzed Geminal Hydroboration of Silyl Alkynes via a New gem-Addition Mechanism
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While 1,2-addition represents the most common mode of alkyne hydroboration, herein we describe a new 1,1-hydroboration mode. It is the first demonstration of gem-(H,B) addition to an alkyne triple bond. With the superior [CpRu(MeCN)3]PF6 catalyst, a range of silyl alkynes reacted efficiently with HBpin under mild conditions to form various synthetically useful silyl vinyl boronates with complete stereoselectivity and broad functional group compatibility. An extension to germanyl alkynes and the hydrosilylation of alkynyl boronates toward the same type of products were also achieved. Mechanistically, this process features a new pathway featuring gem-(H,B) addition to form the key α-boryl-α-silyl Ru-carbene intermediate followed by silyl migration. It is believed that the orbital interaction between boron and Cβ in the coplanar relationship between the boron atom and the ruthenacyclopropene ring preceding boron migration is responsible for the new reactivity. Control experiments and DFT (including molecular dynamics) calculations provided important insights into the mechanism, which excluded the involvement of a metal vinylidene intermediate. This study represents a new step forward not only for alkyne hydroboration but also for other geminal additions of alkynes.
- Feng, Qiang,Wu, Haonan,Li, Xin,Song, Lijuan,Chung, Lung Wa,Wu, Yun-Dong,Sun, Jianwei
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supporting information
p. 13867 - 13877
(2020/09/21)
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- Oxidation of Alkynyl Boronates to Carboxylic Acids, Esters, and Amides
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A general efficient protocol was developed for the synthesis of carboxylic acids, esters, and amides through oxidation of alkynyl boronates, generated directly from terminal alkynes. This protocol represents the first example of C(sp)?B bond oxidation. This approach displays a broad substrate scope, including aryl and alkyl alkynes, and exhibits excellent functional group tolerance. Water, primary and secondary alcohols, and amines are suitable nucleophiles for this transformation. Notably, amino acids and peptides can be used as nucleophiles, providing an efficient method for the synthesis and modification of peptides. The practicability of this methodology was further highlighted by the preparation of pharmaceutical molecules.
- Li, Chenchen,Li, Ruoling,Zhang, Bing,Zhao, Pei,Zhao, Wanxiang
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supporting information
p. 10913 - 10917
(2020/05/25)
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- Copper-catalyzed dehydrogenative borylation of terminal alkynes with pinacolborane
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LCuOTf complexes [L = cyclic (alkyl)(amino)carbenes (CAACs) or N-heterocyclic carbenes (NHCs)] selectively promote the dehydrogenative borylation of C(sp)-H bonds at room temperature. It is shown that σ,π-bis(copper) acetylide and copper hydride complexes are the key catalytic species.
- Romero, Erik A.,Jazzar, Rodolphe,Bertrand, Guy
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p. 165 - 168
(2016/12/30)
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- Ligand survey results in identification of PNP pincer complexes of iridium as long-lived and chemoselective catalysts for dehydrogenative borylation of terminal alkynes
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Following the report on the successful use of SiNN pincer complexes of iridium as catalysts for dehydrogenative borylation of terminal alkynes (DHBTA) to alkynylboronates, this work examined a wide variety of related pincer ligands in the supporting role in DHBTA. The ligand selection included both new and previously reported ligands and was developed to explore systematic changes to the SiNN framework (the 8-(2-diisopropylsilylphenyl)aminoquinoline). Surprisingly, only the diarylamido/bis(phosphine) PNP system showed any DHBTA reactivity. The specific PNP ligand (bearing two diisopropylphosphino side donors) used in the screen showed DHBTA activity inferior to SiNN. However, taking advantage of the ligand optimization opportunities presented by the PNP system via the changes in the substitution at phosphorus led to the discovery of a catalyst whose activity, longevity, and scope far exceeded that of the original SiNN archetype. Several Ir complexes were prepared in a model PNP system and evaluated as potential intermediates in the catalytic cycle. Among them, the (PNP)Ir diboryl complex and the borylvinylidene complex were shown to be less competent in catalysis and thus likely not part of the catalytic cycle.
- Lee, Chun-I,Demott, Jessica C.,Pell, Christopher J.,Christopher, Alyson,Zhou, Jia,Bhuvanesh, Nattamai,Ozerov, Oleg V.
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p. 6572 - 6582
(2015/10/28)
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- Synthesis of Triborylalkenes from Terminal Alkynes by Iridium-Catalyzed Tandem C-H Borylation and Diboration
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A two-step reaction to convert terminal alkynes into triborylalkenes is reported. In the first step, the terminal alkyne and pinacolborane (HBpin) are converted into an alkynylboronate, which is catalyzed by an iridium complex supported by a SiNN pincer l
- Lee, Chun-I,Shih, Wei-Chun,Zhou, Jia,Reibenspies, Joseph H.,Ozerov, Oleg V.
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supporting information
p. 14003 - 14007
(2016/01/25)
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- Catalytic dehydrogenative borylation of terminal alkynes by a SiNN pincer complex of iridium
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Compounds with carbon-boron bonds are versatile intermediates for building more complex molecules via the elaboration of the carbon-boron bonds into other carbon-element bonds. The synthesis of carbon-boron bonds by catalytic dehydrogenative borylation of carbon-hydrogen bonds with dialkoxyboranes (RO)2BH is particularly attractive. It has been demonstrated for a variety of carbon-hydrogen bond types but not for the C(sp)-H bonds of terminal alkynes, for which hydroboration of the triple bond is a competing process. We report a new iridium catalyst that is strictly chemoselective for C-H borylation of terminal alkynes. The key to the success of this catalyst appears to be the new ancillary SiNN pincer ligand that combines amido, quinoline, and silyl donors and gives rise to structurally unusual Ir complexes. A variety of terminal alkynes (RC≡C-H) can be converted to their alkynylboronates (RC≡C-Bpin, where pin = pinacolate) in high yield and purity within minutes at ambient temperature.
- Lee, Chun-I,Zhou, Jia,Ozerov, Oleg V.
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supporting information
p. 3560 - 3566
(2013/04/23)
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- Highly regio- and stereoselective synthesis of multialkylated olefins through carbozirconation of alkynylboronates and sequential Negishi and Suzuki-Miyaura coupling reactions
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Two Nobel couplings: The synthesis of tri- and tetraalkylated olefins has been achieved (see scheme). These multialkylated olefins were prepared by the zirconocene-mediated carbometalation of 1-alkynylboronates and subsequent sequential C-C bond formation
- Nishihara, Yasushi,Okada, Yoshiaki,Jiao, Jiao,Suetsugu, Masato,Lan, Ming-Tzu,Kinoshita, Megumi,Iwasaki, Masayuki,Takagi, Kentaro
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supporting information; experimental part
p. 8660 - 8664
(2011/11/06)
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- Hydrolytic stability of nitrogenous-heteroaryltrifluoroborates under aqueous conditions at near neutral pH
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The hydrolytic stability of heteroaryltrifluoroborates under physiological conditions has been analyzed by 19F NMR spectroscopy and is found to be greatly enhanced by the presence of endocyclic ring nitrogens. Stability is further enhanced by the presence of exocyclic electron withdrawing substituents. As with aryltrifluoroborates, NMR analysis suggests that the hydrolysis proceeds via single rate-determining step reflecting loss of the first fluoride atom. The stability of these complexes is significant both in terms of metal catalyzed cross-coupling reactions as well as the potential for generating boronic acid based 18F-PET imaging agents.
- Li, Ying,Asadi, Ali,Perrin, David M.
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experimental part
p. 377 - 382
(2009/12/04)
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- Platinum(0)-catalyzed diboration of alkynylboronates and alkynylphosphonates with bis(pinacolato)diborane(4) (see abstract)
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The platinum(0)-catalyzed diboration addition reaction of bis(pinacolato)diborane(4) [(Me4C2O2)BB(O2C2Me4 ), 1] with various 1-alkynylphosphonates and 1-alkynylboronates 3a-d gave the desired novel cis-1,2-diboronated vinylphosphonate and trisboronated alkene products 5a, 5b and 5c, 5d respectively, in high yields. No detectable amount of the desired trisboronated alkene products 5c and 5d were isolated when the alkynylboronate was immediately added to a toluene solution of the catalyst and bis(pinacolato)diborane(4) followed by stirring overnight at 80 °C. Under these conditions, cis-1,2-diboronated alkenes 6c and 6d were obtained in 100% conversion yields. Only after changing the reaction conditions were 5c and 5d obtained in high yields. The structure and configuration of the new compounds have been fully characterized by 1H, 13C, 31P, and 11B NMR, GCMS, elemental analysis, and single-crystal X-ray structure determination. The structure of 5d was found to be fully isomorphous to that of 5c, with the C6H5 ring located in place (and similarly disordered about the 2-fold symmetry axis) of the C4H9 residue; therefore the results of the diffraction analysis, crystal data, and details of the structure determination of 5d are not included.
- Abu Ali, Hijazi,Al Quntar, Abed El Aziz,Goldberg, Israel,Srebnik, Morris
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p. 4533 - 4539
(2008/10/08)
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