- Electrophilic aromatic addition reaction: Electrophilic attack at an aromatic H substituent position
-
(Chemical Equation Presented) We report and propose a mechanism for an unusual electrophilic aromatic addition reaction (AdEAr). During our preparation of 5,7-dibromo-8-methoxyquinaldine as a key intermediate in the synthesis of 7-bromoquinaldine-5,8-dione, direct bromination in either acidic or neutral conditions led only to the formation of 5-bromo-8-methoxyquinaldine. Under basic methanolic conditions, however, we unexpectedly obtained the 5,7-dibromo-8,8-dimethoxy-7,8-dihydroquinaldine adduct 2a. This result not only allows for the functionalization of aromatic compounds via the addition adducts, but also introduces the possibility of an alternate mechanism for electrophilic substitution reactions.
- Han, Young Choi,Srisook, Ekaruth,Kun, Sam Jang,Dae, Yoon Chi
-
-
Read Online
- Versatile functionalization of electron rich-fused heterocyclic arenes via electrophilic aromatic addition reaction and their applications
-
Divergent functionalized 8-methoxyquinaldines were synthesized via regioselective debromination, 1,3-bromine shift process, aromatization with treatment of a strong base, nucleophilic substitution reaction at the C7 position using amines and cyanide as a nucleophile in the absence of a metal source and a catalyst from an unusual electrophilic aromatic addition (AdEAr) reaction products 7 and 8. In addition, quinaldine-7,8-dione was prepared by presence of CAN (ceric ammonium nitrate) in AcOH and H2O for 10 min at room temperature from N-(alkylamino)-8-methoxyquinalidines. During the AdEAr reaction, new stereoselective dearomatized addition products were generated via discriminative reaction routes depending on the methoxy and bromine occupancy position. The AdEAr reaction not only allowed for the functionalization of electron rich-fused heterocyclic arenes, but also provided a new synthetic route to an alternative mechanism for electrophilic aromatic substitution reactions.
- Jang, Keun Sam,Shin, Dong Seok,Srisook, Ekaruth,Song, Ho-Chun,Chi, Dae Yoon
-
-
Read Online
- Facile Oxidation of Fused 1,4-Dimethoxybenzenes to 1,4-Quinones Using NBS: Fine-Tuned Control over Bromination and Oxidation Reactions
-
(Matrix Presented) Fused 1,4-dimethoxybenzenes could be oxidized to benzoquinones by either direct oxidation or demethylation-oxidation. The oxidative demethylation of 5,8-dimethoxy-2-methylquinoline using 1.1 equiv of NBS in aqueous THF and a catalytic amount of H2SO4 at 20°C for 5 min gave 2-methylquinoline-5,8-dione in 98% yield without bromination. Moreover, we can control either bromination or oxidative demethylation, or both reactions.
- Kim, Dong Wook,Choi, Han Young,Lee, Kee-Jung,Chi, Dae Yoon
-
-
Read Online
- Sensitized luminescence in dinuclear lanthanide(iii) complexes of bridging 8-hydroxyquinoline derivatives with different electronic properties
-
Three new dinuclear lanthanide(iii) complexes {Eu(hfac)3(H 2O)}2(μ-HPhMq)2 (2) and {Ln(hfac) 3(H2O)}2(μ-HMe2NC 6H4Mq)2 (Ln = Eu, 3; Nd, 4) with 8-hydroxylquinoline derivatives in μ-phenol mode were synthesized and characterized, where hfac- = hexafluoroacetylacetonate, HPhMq = 2-methyl-5-phenylquinolin-8-ol, and HMe2C6H4Mq = 5-(4-(dimethylamino)phenyl)-2-methylquinolin-8-ol. Compared with that (400 nm) for {Eu(hfac)3}2(μ-HMq)2 (1, HMq = 2-methy-8-hydroxylquinoline), the excitation wavelength for sensitized lanthanide luminescence is extended to ca. 420 nm for 2, and 500 nm for 4 by introducing a phenyl or 4-(dimethylamino)phenyl to 8-hydroxylquinoline. These dinuclear lanthanide(iii) complexes exhibit distinctly fluoride-induced lanthanide(iii) emission enhancement in both intensity and lifetime due to replacing coordination water molecules or formation of strong O-H...F hydrogen bonds with coordinated H2O and μ-phenol, thus suppressing significantly the non-radiative O-H oscillators. The Royal Society of Chemistry.
- Xu, Hai-Bing,Li, Jia,Shi, Lin-Xi,Chen, Zhong-Ning
-
experimental part
p. 5549 - 5556
(2011/06/27)
-
- PYRIDAZINONE DERIVATIVE AND PDE INHIBITOR CONTAINING THE SAME AS ACTIVE INGREDIENT
-
It is to provide a novel pyridazinone derivative represented by the following general formula (1), which is useful as a pharmaceutical and has a phosphodiesterase inhibitory action: wherein R1 represents H or C1-6 alkyl, each of R2 and R3 represents H, X, C1-6 alkoxy, Z represents O or S, and A represents AA or BB, wherein AA represents: and BB represents: wherein R4 represents H or C1-6 alkyl, and each of R5 and R6 represents C1-6 alkyl.
- -
-
Page/Page column 77
(2010/04/25)
-
- PYRAZOLONE DERIVATIVE AND PDE INHIBITOR CONTAINING THE SAME AS ACTIVE INGREDIENT
-
It is to provide a novel pyrazolone derivative represented by the following general formula (1), which is useful as a pharmaceutical and has a phosphodiesterase inhibitory action: wherein R1,R2: C1-6 alkyl; R3,R4: H, X, C1-6 alkoxy; Z:O, S; A:AA, BB, wherein AA represents wherein BB represents wherein R5: H, C1-6 alkyl ; R6,R7: C1-6 alkyl.
- -
-
Page/Page column 57
(2010/04/25)
-
- 8-Methoxyquinolines as PDE4 inhibitors.
-
The synthesis and pharmacological profile of a novel series of 2-substituted 8-methoxyquinolines is described. The 2-trifluoromethyl compound was found to be a potent inhibitor of phosphodiesterase type 4 (PDE4).
- Billah, Motasim,Buckley, George M,Cooper, Nicola,Dyke, Hazel J,Egan, Robert,Ganguly, Ashit,Gowers, Lewis,Haughan, Alan F,Kendall, Hannah J,Lowe, Christopher,Minnicozzi, Michael,Montana, John G,Oxford, Janet,Peake, Joanna C,Picken, C Louise,Piwinski, John J,Naylor, Robert,Sabin, Verity,Shih, Neng-Yang,Warneck, Julie B H
-
p. 1617 - 1619
(2007/10/03)
-
