Synthesis of Indeno[b]indole and Naphtho[a]carbazole Derivatives Involving Diels‐Alder Reaction of Isobenzofurans. Issue 26 (12th September 2017)

• Record Type: Journal Article
• Authors: Sankar, Elumalai; Karunakaran, Jayachandran; Dhivyapirabha, Loganathan; Mohanakrishnan, Arasambattu K.
• Is Part Of: ChemistrySelect. Volume 2:Issue 26(2017)
• Page Start: 7899
• Page End: 7903
• Publication Date: 2017-09-12
• Subjects: Diels-Alder -- Fischer indole synthesis -- indeno[b]indole -- indeno[b]indolones -- Isobenzofuran -- naphtho[a]carbazole; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/slct.201701851
• Languages: English
• ISSNs: 2365-6549

Abstract

Abstract: Diels‐Alder reaction of 1, 3‐diarylisobenzofurans with cyclopenten‐1‐one as well as 2‐cyclohexen‐1‐one in the presence of TMSOTf in DCM at 0 °C furnished 4, 5‐diarylbenzo[ e ]inden‐1‐ones and 6, 7‐diarylbenzo[ f ]α‐tetralones. The benzo[ e ]inden‐1‐ones/benzo[ f ]α‐tetralones upon Fischer indolization led to the formation of indeno[ b ]indoles and dihydronaphtho[ a ]carbazoles, respectively. Abstract : Isobenzofurans upon Diels‐Alder reaction with 2‐cyclopeten‐1‐one/2‐cyclohexen‐1‐one in the presence of TMSOTf in DCM at 0 °C led to the formation respective naphthocycloalkanones in good yields. The naphthocycloalkanones underwent Fischer indolization with arylhydrazines in acetic acid at reflux to furnish indeno[ b ]indoles and dihydronaphtho[ a ] carbazoles. The dihydronaphtho[ a ] carbazoles upon aromatization using 10 % Pd/C in xylenes at reflux afforded naphtho[ a ]carbazoles. Transformation of indeno[ b ]indole into the respective indeno[ b ]indolones could be achieved involving DDQ‐mediated oxidation.