Synthesis of Dibenzofurans via Palladium-Catalyzed Phenol-Directed C–H Activation/C–O Cyclization
摘要:
A practical, Pd(0)/Pd(II)-catalyzed reaction was developed for phenol-directed C-H activation/C-O cyclization using air as an oxidant. The turnover-limiting step of the process was found to be C-O reductive elimination instead of C-H activation. This reaction can tolerate a variety of functional groups and is complementary to the previous methods for the synthesis of substituted dibenzofurans.
Sterically congested quinone methides in photodehydration reactions of 4-hydroxybiphenyl derivatives and investigation of their antiproliferative activity
作者:Nikola Basarić、Nikola Cindro、Damir Bobinac、Kata Mlinarić-Majerski、Lidija Uzelac、Marijeta Kralj、Peter Wan
DOI:10.1039/c1pp05182b
日期:2011.12
In aqueous media, photochemical excitation (S1) of hydroxyadamantyl, diphenylhydroxymethyl, and hydroxypropyl derivatives of 4-phenylphenol 5–9 leads to solvent-assisted deprotonation of the phenol OH, and protonation of the benzyl alcohol coupled with dehydration, that delivers quinone methides (QMs) 14–18. The QMs react with CH3OH converting them in high quantum yields to the photosolvolysis products
Synthesis of Dibenzopyranones through Palladium-Catalyzed Directed C-H Activation/Carbonylation of 2-Arylphenols
作者:Shuang Luo、Fei-Xian Luo、Xi-Sha Zhang、Zhang-Jie Shi
DOI:10.1002/anie.201304295
日期:2013.9.27
Dibenzopyranones were synthesized by a palladium‐catalyzed phenol‐directed C–H activation/carbonylation of 2‐phenylphenol derivatives in the presence of CO. Pd(OAc)2 was used as a catalyst and Cu(OAc)2 as a catalytic oxidant in the presence of air.
Synthesis of 2,2′-biphenols through direct C(sp<sup>2</sup>)–H hydroxylation of [1,1′-biphenyl]-2-ols
作者:Shitao Duan、Yuanshuang Xu、Xinying Zhang、Xuesen Fan
DOI:10.1039/c6cc04756d
日期:——
A novel synthesis of diversely substituted 2,2′-biphenols through Pd(ii)-catalyzed,tBuOOH-oxidized, and hydroxyl-directed C(sp2)–H hydroxylation of [1,1′-biphenyl]-2-ols has been developed.
significance and in great demand. Among these, C–H bondsilylation provides a powerful and straightforward synthetic method to form diverse silacycles in an atom- and step-economical fashion. However, C–H bondsilylation has not been used to access any six-membered silicon-bridged π-conjugated scaffolds and enantioselective six-membered C–H silylation has never been presented. Herein, we successfully
C / Si转换策略已被认为是发现药物和材料的有用和高效的策略。因此,开发访问各种硅杂环的方法学具有重要意义和需求。其中,C–H键甲硅烷基化提供了一种强大而直接的合成方法,可以以原子经济和分步经济的方式形成各种硅杂环。但是,尚未使用C–H键甲硅烷基化来获得任何六元硅桥π-共轭支架,并且从未提出对映选择性的六元C–H甲硅烷基化。在这里,我们通过C–H键甲硅烷基化成功地获得了多种多样的六元π共轭二苯并恶唑啉,并研究了它们的光物理性质。此外,我们认识到对映选择性六元C H硅烷化可以直接提供具有高ee(高达95%ee)的平面手性茂金属恶二唑烷。我们还证明了通过各种其他转化,二苯并恶唑啉和平面手性茂金属稠合的苯并恶唑啉作为有价值的合成中间体的合成有用性。此外,利用我们的方法设计并快速构建了六元硅桥梯π共轭体系。还详细评估了“异构化”和“硅”对分子几何形状和光物理性质的影响。利用我们的方法设计并快速构
A New Type of Excited-State Intramolecular Proton Transfer: Proton Transfer from Phenol OH to a Carbon Atom of an Aromatic Ring Observed for 2-Phenylphenol<sup>1</sup>
作者:Matthew Lukeman、Peter Wan
DOI:10.1021/ja0267831
日期:2002.8.1
mechanism of exchange that involves excited-state intramolecular proton transfer (ESIPT) from the phenol to the 2'-carbon position of the benzene ring not containing the phenol, to generate the corresponding keto tautomer (an o-quinone methide). This is the first explicit example of a new class of ESIPT in which an acidic phenolic proton is transferred to an sp(2)-hybridized carbon of an aromatic ring