- Organophosphorus-catalyzed relay oxidation of H-Bpin: electrophilic C-H borylation of heteroarenes
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A nontrigonal phosphorus triamide (1, P{N[o-NMe-C6H4]2}) is shown to catalyze C-H borylation of electron-rich heteroarenes with pinacolborane (HBpin) in the presence of a mild chloroalkane reagent. C-H borylation proceeds for a range of electron-rich heterocycles including pyrroles, indoles, and thiophenes of varied substitution. Mechanistic studies implicate an initial P-N cooperative activation of HBpin by1to giveP-hydrido diazaphospholene2, which is diverted by Atherton-Todd oxidation with chloroalkane to generateP-chloro diazaphospholene3. DFT calculations suggest subsequent oxidation of pinacolborane by3generates chloropinacolborane (ClBpin) as a transient electrophilic borylating species, consistent with observed substituent effects and regiochemical outcomes. These results illustrate the targeted diversion of established reaction pathways in organophosphorus catalysis to enable a new mode of main group-catalyzed C-H borylation.
- Lipshultz, Jeffrey M.,Fu, Yue,Liu, Peng,Radosevich, Alexander T.
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p. 1031 - 1037
(2021/02/06)
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- Zinc catalysed C3-H borylation of indoles and 1,1-diboration of terminal alkynes
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A low catalyst loading Zn(OTf)2-catalysed C3-H borylation of indoles with pinacolborane was developed. This transformation represents the use of an abundant, cheap and environmentally benign zinc catalyst in catalytic direct aromatic C-H borylation and offers a simple and prompt route towards the synthesis of C3-borylated indoles. The 1,1-diboration of terminal alkynes was also achieved using the same catalytic system to produce 1,1-diborylated alkenes.
- Wang, Li,Zhang, Binfeng,Zhang, Hua,Zou, Youliang
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supporting information
p. 11185 - 11188
(2021/11/04)
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- Isodesmic C-H Borylation: Perspectives and Proof of Concept of Transfer Borylation Catalysis
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The potential advantages of using arylboronic esters as boron sources in C-H borylation are discussed. The concept is showcased using commercially available 2-mercaptopyridine as a metal-free catalyst for the transfer borylation of heteroarenes using arylboronates as borylation agents. The catalysis shows a unique functional group tolerance among C-H borylation reactions, tolerating notably terminal alkene and alkyne functional groups. The mechanistic investigation is also described.
- Rochette, étienne,Desrosiers, Vincent,Soltani, Yashar,Fontaine, Frédéric-Georges
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supporting information
p. 12305 - 12311
(2019/08/20)
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- Practical and Scalable Synthesis of Borylated Heterocycles Using Bench-Stable Precursors of Metal-Free Lewis Pair Catalysts
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A practical and scalable metal-free catalytic method for the borylation and borylative dearomatization of heteroarenes has been developed. This synthetic method uses inexpensive and conveniently synthesizable bench-stable precatalysts of the form 1-NHR2-2-BF3-C6H4, commercially and synthetically accessible heteroarenes as substrates, and pinacolborane as the borylation reagent. The preparation of several borylated heterocycles on 2 and 50 g scales was achieved under solvent-free conditions without the use of Schlenk techniques or a glovebox. A kilogram-scale borylation of one of the heteroarene substrates was also achieved using this cost-effective green methodology to exemplify the fact that our methodology can be conveniently implemented in fine chemical industries.
- Jayaraman, Arumugam,Misal Castro, Luis C.,Fontaine, Frédéric-Georges
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supporting information
p. 1489 - 1499
(2018/10/26)
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- PYRROLOPYRIDINE AND PYRROLOPYRIMIDINE INHIBITORS OF KINASES
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The present invention relates to compounds of formula (I) or pharmaceutical acceptable salts, wherein A, B, R1, R2, R3, R4a, R5, and Z are defined in the description. The present invention relates also to methods of making said compounds, and compositions containing said compounds which are useful for inhibiting kinases such as aurora.
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