Coupling of Quinone Monoacetals Promoted by Sandwiched Brønsted Acids: Synthesis of Oxygenated Biaryls
作者:Toshifumi Dohi、Naohiko Washimi、Tohru Kamitanaka、Kei-ichiro Fukushima、Yasuyuki Kita
DOI:10.1002/anie.201101646
日期:2011.6.27
Unusual protons: Brønsted acids sandwiched between sheets of solid acids, such as montmorillonites, activated quinone monoacetals 1 to selectively react with aromatic nucleophiles 2 in an unprecedented substitution reaction. The syntheticutility of the strategy for obtaining highly oxygenated biaryls 3 is highlighted by the synthesis of gilvocarcin aglycones.
Ph<sub>3</sub>P-mediated highly selective C(α)–P coupling of quinone monoacetals with R<sub>2</sub>P(O)H: convenient and practical synthesis of <i>ortho</i>-phosphinyl phenols
作者:Ruwei Shen、Ming Zhang、Jing Xiao、Chao Dong、Li-Biao Han
DOI:10.1039/c8gc02918k
日期:——
A highlyselective Ph3P-mediated C(α)–P coupling reaction of quinone monoacetals with secondary phosphine oxides is developed to provide an effective method for the synthesis of a wide array of ortho-phosphinylphenols in good to excellent yields. This protocol can be adopted for scale-up synthesis directly from cheap and abundant phenols, and the products can be easily obtained in high yields by simple
Efficient Coupling Reaction of Quinone Monoacetal with Phenols Leading to Phenol Biaryls
作者:Tohru Kamitanaka、Koji Morimoto、Kohei Tsuboshima、Daichi Koseki、Hitoho Takamuro、Toshifumi Dohi、Yasuyuki Kita
DOI:10.1002/anie.201608013
日期:2016.12.12
phenol biaryls by the cross‐couplings of quinone monoacetals (QMAs) and phenols is reported. The Brønsted acid catalytic system in 1,1,1,3,3,3‐hexafluoro‐2‐propanol was found to be particularly efficient for this transformation. This reaction can be extended to the synthesis of various phenol biaryls, including sterically hindered biaryls, with yields ranging from 58 to 90 % under mild reaction conditions
Controlled couplings of quinone monoacetals using reusable polystyrene-anchored specific proton catalyst
作者:Toshifumi Dohi、Yinjun Hu、Tohru Kamitanaka、Yasuyuki Kita
DOI:10.1016/j.tet.2012.07.089
日期:2012.10
Controlled couplings of quinone monoacetals 1 with soft nucelophiles have been achieved using a new and reusable perfluorobenzoic acid (PFBA) immobilized on polystyrene beads as an efficient polymer-anchored specific proton. Various advantages regarding the recovery, reusability, and reproducibility as well as the high chemoselectivity toward quinone monoacetals 1 have been determined as the key features of the cleaner systems with newly developed solid acid promoter for the reactions. (C) 2012 Elsevier Ltd. All rights reserved.