Taku Shoji, Daichi Ando, Masayuki Iwabuchi, Atom Hamasaki, Shigeki Mori, Tetsuo Okujima, Ryuta Sekiguchi, Shunji Ito
{"title":"Synthesis of 2-Amino-4-arylazulenes from 8-Aryl-2<i>H</i>-cyclohepta[<i>b</i>]furan-2-ones and Transformation into 6-Aryl-7<i>H</i>-naphth[3,2,1-<i>cd</i>]azulen-7-ones.","authors":"Taku Shoji, Daichi Ando, Masayuki Iwabuchi, Atom Hamasaki, Shigeki Mori, Tetsuo Okujima, Ryuta Sekiguchi, Shunji Ito","doi":"10.1021/acs.joc.4c01394","DOIUrl":null,"url":null,"abstract":"<p><p>2-Amino-4-arylazulene derivatives were prepared from 8-aryl-2<i>H</i>-cyclohepta[<i>b</i>]furan-2-ones, which were converted into 6-aryl-7<i>H</i>-naphth[3,2,1-<i>cd</i>]azulen-7-ones through a several step process. The reaction of 8-aryl-2<i>H</i>-cyclohepta[<i>b</i>]furan-2-ones bearing an ester group at the 3-position with malononitrile in the presence of triethylamine afforded 2-amino-4-arylazulenes. The prepared 2-amino-4-arylazulenes were converted to the corresponding 2-chloro derivatives by the Sandmeyer reaction, which were subsequently transformed into 2,4-diarylazulenes by Suzuki-Miyaura coupling with various aryl boronic acids. 2,4-Diarylazulenes underwent intramolecular cyclization between aryl and cyano groups by Brønsted acid to give 6-aryl-7<i>H</i>-naphth[3,2,1-<i>cd</i>]azulen-7-ones. UV/vis spectral analysis revealed that 6-aryl-7<i>H</i>-naphth[3,2,1-<i>cd</i>]azulen-7-one with a <i>N</i>,<i>N</i>-dimethylaminophenyl group at the 6-position exhibited a broad and strong absorption band in the visible region due to intramolecular charge transfer. Furthermore, 6-aryl-7<i>H</i>-naphth[3,2,1-<i>cd</i>]azulen-7-ones exhibited halochromism in 30% CF<sub>3</sub>CO<sub>2</sub>H/CH<sub>2</sub>Cl<sub>2</sub>. Although fluorescence was not observed in solution, 8-aryl-2<i>H</i>-cyclohepta[<i>b</i>]furan-2-ones with an ester function were found to fluoresce in the solid state. 6-Aryl-7<i>H</i>-naphth[3,2,1-<i>cd</i>]azulen-7-ones also displayed spectral changes with good reversibility under the electrochemical redox conditions.</p>","PeriodicalId":57,"journal":{"name":"The Journal of Organic Chemistry","volume":" ","pages":"16375-16389"},"PeriodicalIF":3.3000,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Journal of Organic Chemistry","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1021/acs.joc.4c01394","RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/11/4 0:00:00","PubModel":"Epub","JCR":"Q1","JCRName":"CHEMISTRY, ORGANIC","Score":null,"Total":0}
引用次数: 0
Abstract
2-Amino-4-arylazulene derivatives were prepared from 8-aryl-2H-cyclohepta[b]furan-2-ones, which were converted into 6-aryl-7H-naphth[3,2,1-cd]azulen-7-ones through a several step process. The reaction of 8-aryl-2H-cyclohepta[b]furan-2-ones bearing an ester group at the 3-position with malononitrile in the presence of triethylamine afforded 2-amino-4-arylazulenes. The prepared 2-amino-4-arylazulenes were converted to the corresponding 2-chloro derivatives by the Sandmeyer reaction, which were subsequently transformed into 2,4-diarylazulenes by Suzuki-Miyaura coupling with various aryl boronic acids. 2,4-Diarylazulenes underwent intramolecular cyclization between aryl and cyano groups by Brønsted acid to give 6-aryl-7H-naphth[3,2,1-cd]azulen-7-ones. UV/vis spectral analysis revealed that 6-aryl-7H-naphth[3,2,1-cd]azulen-7-one with a N,N-dimethylaminophenyl group at the 6-position exhibited a broad and strong absorption band in the visible region due to intramolecular charge transfer. Furthermore, 6-aryl-7H-naphth[3,2,1-cd]azulen-7-ones exhibited halochromism in 30% CF3CO2H/CH2Cl2. Although fluorescence was not observed in solution, 8-aryl-2H-cyclohepta[b]furan-2-ones with an ester function were found to fluoresce in the solid state. 6-Aryl-7H-naphth[3,2,1-cd]azulen-7-ones also displayed spectral changes with good reversibility under the electrochemical redox conditions.
期刊介绍:
The Journal of Organic Chemistry welcomes original contributions of fundamental research in all branches of the theory and practice of organic chemistry. In selecting manuscripts for publication, the editors place emphasis on the quality and novelty of the work, as well as the breadth of interest to the organic chemistry community.