95843-97-3Relevant academic research and scientific papers
Photoinduced Miyaura Borylation by a Rare-Earth-Metal Photoreductant: The Hexachlorocerate(III) Anion
Qiao, Yusen,Yang, Qiaomu,Schelter, Eric J.
, p. 10999 - 11003 (2018)
The first photoinduced carbon(sp2)–heteroatom bond forming reaction by a rare-earth-metal photoreductant, a Miyaura borylation, has been achieved. This simple, scalable, and novel borylation method that makes use of the hexachlorocerate(III) anion ([CeIIICl6]3?, derived from CeCl3) has a broad substrate scope and functional-group tolerance and can be conducted at room temperature. Combined with Suzuki–Miyaura cross-coupling, the method is applicable to the synthesis of various biaryl products, including through the use of aryl chloride substrates.
Decarboxylative Borylation of Stabilized and Activated Carbon Radicals
Li, Xiaojuan,Ni, Shengyang,Pan, Yi,Wang, Yi,Zhang, Qiang,Zhang, Weigang
supporting information, p. 21875 - 21879 (2020/10/02)
Redox-active esters (RAEs) as active radical precursors have been extensively studied for C?B bond formations. However, the analogous transformations of stabilized radicals from the corresponding acid precursors remain challenging owing to the strong preference towards single-electron oxidation to the stable carbocations. This work describes a general strategy for rapid access to various aliphatic and aromatic boronic esters by mild photoinduced decarboxylative borylation. Both aryl and alkyl radicals could be generated from the leaving group-assisted N-hydroxybenzimidoyl chloride esters, even α-CF3 substituted substrates could be activated for further elaboration.
Scalable, Metal- and Additive-Free, Photoinduced Borylation of Haloarenes and Quaternary Arylammonium Salts
Mfuh, Adelphe M.,Doyle, John D.,Chhetri, Bhuwan,Arman, Hadi D.,Larionov, Oleg V.
supporting information, p. 2985 - 2988 (2016/03/19)
We report herein a simple, metal- and additive-free, photoinduced borylation of haloarenes, including electron-rich fluoroarenes, as well as arylammonium salts directly to boronic acids. This borylation method has a broad scope and functional group tolerance. We show that it can be further extended to boronic esters and carried out on gram scale as well as under flow conditions.
A comparative study of the relative stability of representative chiral and achiral boronic esters employing transesterification
Roy, Chandra D.,Brown, Herbert C.
, p. 879 - 887 (2008/02/11)
A comparative study of the transesterification of five representative chiral and achiral boronic esters with various structurally modified diols was undertaken to qualitatively understand the factors influencing the relative stability of these boronic esters. Several factors such as chelation, conformation, steric bulk of the substituents, size of the heterocycle, and entropy influence the relative rate of transesterification as well as the stability of the boronic esters. Amongst these boronic esters, pinanediol phenylboronic ester was found to be the most stable boronic ester whereas DIPT boronic ester appeared to be thermodynamically the least stable one. The transesterification with sterically hindered diols was observed to be relatively slow, but afforded thermodynamically more stable boronic esters. Boronic esters derived from cis-cyclopentanediols and the bicyclo[2.2.1]heptane-exo,exo-2,3- diols are relatively more stable. This study not only presents the qualitative picture of relative stability of various boronic esters, but also provides helpful hints regarding the possible recovery of chiral auxiliaries. Many C 2-symmetric chiral auxiliaries, such as 2,3-butanediol, 2,4-pentanediol, DIPT, and cis-cyclohexane-1,2-diol, can be retrieved by simple transesterification of the corresponding boronic esters with commercial inexpensive diols, such as pinacol, 1,3-propanediol, and neopentyl glycol.
Stability of boronic esters - Structural effects on the relative rates of transesterification of 2-(phenyl)-1,3,2-dioxaborolane
Roy, Chandra D.,Brown, Herbert C.
, p. 784 - 790 (2007/10/03)
Relative rates of reaction of the achiral cyclic phenylboronic ester 2-(phenyl)-1,3,2-dioxaborolane with a wide variety of structurally modified diols, have been studied to understand the factors influencing the relative stabilities of boronic esters. It is found that the alkyl substituents on the α-carbons of diols slow down the transesterification, but produce thermodynamically more stable boronic ester. Six-membered boronic esters are thermodynamically more stable than their corresponding five-membered analogs. Amongst cyclic 1,2-diols, cis-1,2-cyclopentanediol displaces ethylene glycol instantaneously whereas trans-1,2-cyclopentanediol is totally unreactive, which suggests that the cis-stereochemistry of the 1,2-diol is a prerequisite for transesterification. Among the 1,5-diols, diethanolamine displaces ethylene glycol quite rapidly forming a more stable bicyclic chelate in which nitrogen is attached to boron by a coordinating bond (as evident by 11B NMR spectroscopy). The oxygen atom of di(ethylene glycol) and the sulfur atom of 2,2′-thiodiethanol do not assist in displacing the ethylene glycol from their boronic esters.
