排序方式: 共有16条查询结果,搜索用时 93 毫秒
11.
Aleksandra Nilova Prof. Dr. Paul A. Sibbald Prof. Dr. Edward J. Valente Gisela A. González-Montiel H. Camille Richardson Dr. Kevin S. Brown Prof. Dr. Paul Ha-Yeon Cheong Prof. Dr. David R. Stuart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(24):7168-7175
Herein, the synthesis of 1,2,3,4-tetrasubstituted benzenoid rings, motifs found in pharmaceutical, agrochemical, and natural products, is described.[1] In the past, the regioselective syntheses of such compounds have been a significant challenge. This work reports a method using substituted arynes derived from aryl(Mes)iodonium salts to access a range of densely functionalized 1,2,3,4-tetrasubstituted benzenoid rings. Significantly, it was found that halide substituents are compatible under these conditions, enabling post-synthetic elaboration via palladium-catalyzed coupling. This concise strategy is predicated on two regioselective events: 1) ortho- deprotonation of aryl(Mes)iodonium salts to generate a substituted aryne intermediate, and 2) regioselective trapping of said arynes, thereby improving previously reported reaction conditions to generate arynes at room temperature and in shorter reaction times. Density functional theory (DFT) computations and linear free energy relationship (LFER) analysis suggest the regioselectivity of deprotonation is influenced by both proximal and distal ring substituents on the aryne precursor. A competition experiment further reveals the role of arene substituents on relative reactivity of aryl(Mes)iodoniums as aryne precursors. 相似文献
12.
Dr. Sunil Kumar Sunnam Dr. Jitendra D. Belani 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(34):8846-8850
Arylation via ortho C−H activation by the aid of directing groups has been explored recently by many researchers. Herein, a palladium-catalyzed C−H arylation using 8-aminoquinoline as a bidentate directing group has been developed. The reaction furnishes only C−H arylation, unlike previous methods where cyclization to corresponding isoquinolones is observed. More interestingly, sequential C−H functionalization was observed when methylacrylate and acrylonitrile was added; this led to C−H olefination with the aryl group, which was installed from the aryne precursor. 相似文献
13.
The semiempirical AM1 SCF-MO method is used to study the benzyne mechanism for aromatic nucleophilic substitution of various
m-substituted chlorobenzenes and 3-chloropyridine. The calculations predict that most of the fixed substituents studied here
would induce the formation of 2,3-arynes through their electron-withdrawing resonance or inductive effects. The geometry and
electronic structure of the 2,3- and 3,4-arynes investigated here, confirm the generally acceptedo-benzyne structure postulated for arynes. The sites of nucleophilic addition to arynes as predicted here are in fair agreement
with expectation and experimental findings. 相似文献
14.
Dr. Motoki Ito Haruna Yamazaki Aguri Ito Ryuhei Oda Moeka Komiya Dr. Kazuhiro Higuchi Prof. Dr. Shigeo Sugiyama 《European journal of organic chemistry》2023,26(31):e202300458
We have developed an improved method for generating aryne from o-triazenylarylboronic acids. Unlike the previous method that required excess o-triazenylarylboronic acids as aryne precursors, we used corresponding boronates as limiting reagents, which resulted in high yields. By combining the formation of boronates and aryne generation through silica gel treatment in one-pot, we were able to effectively use a wide range of o-triazenylarylboronic acids in reactions with various arynophiles. This one-pot method was particularly suitable for transforming complex aryne precursors with different functional groups. 相似文献
15.
Dr. Kazuhiko Adachi Shunsuke Hirose Dr. Yasuyuki Ueda Prof. Dr. Hidehiro Uekusa Prof. Dr. Toshiyuki Hamura 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(11):3665-3669
Thermal isomerization of cyclobutaphenanthrene to o-quinodimethane was investigated. Sterically congested substituents or electron-donating substituents on the four-membered ring promoted the ring-opening, affording o-quinodimethane in a relatively stable form. Isolation of the newly prepared o-quinodimethane allowed its structural elucidation and investigation of its potential reactivities. Dual [4+2] cycloaddition of an aryne and o-quinodimethane afforded tetrabenzopentacene, demonstrating the synthetic application of the isolated compound. 相似文献
16.