174090-36-9Relevant articles and documents
Electrosynthesis of benzylboronic acids and esters
Pintaric,Laza,Olivero,Du?ach
, p. 8031 - 8033 (2004)
A novel preparation of benzylboronic acids and esters is described by using an electrochemical reductive coupling reaction between benzylic halides and borating agents (trialkylborates or pinacolborane). The reaction is carried out at room temperature in DMF or THF with the use of a sacrificial magnesium anode in a single-compartment cell.
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.
Rhodium-Catalyzed Regiodivergent Synthesis of Alkylboronates via Deoxygenative Hydroboration of Aryl Ketones: Mechanism and Origin of Selectivities
Zhang, Bing,Xu, Xin,Tao, Lei,Lin, Zhenyang,Zhao, Wanxiang
, p. 9495 - 9505 (2021/08/04)
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.
Practical Synthesis of Allyl, Allenyl, and Benzyl Boronates through SN1′-Type Borylation under Heterogeneous Gold Catalysis
Miura, Hiroki,Hachiya, Yuka,Nishio, Hidenori,Fukuta, Yohei,Toyomasu, Tomoya,Kobayashi, Kosa,Masaki, Yosuke,Shishido, Tetsuya
, p. 758 - 766 (2021/02/03)
Efficient borylation of sp3 C-O bonds by supported Au catalysts is described. Au nanoparticles supported on TiO2 showed high activity under mild conditions employing low catalyst loading conditions without the aid of any additives, such as phosphine and bases. A variety of allyl, propargyl, and benzyl substrates participated in the heterogeneously catalyzed reactions to furnish the corresponding allyl, allenyl, and benzyl boronates in high yields. Besides, Au/TiO2 was also effective for the direct borylation of allylic and benzylic alcohols. A mechanistic investigation based on a Hammett study and control experiments revealed that sp3 C-O bond borylation over supported Au catalysts proceeded through SN1′-type mechanism involving the formation of a carbocationic intermediate. The high activity, reusability, and environmental compatibility of the supported Au catalysts as well as the scalability of the reaction system enable the practical synthesis of valuable organoboron compounds.
