A novel and efficient tandem protocol for the swift synthesis of dihydrobenzo[]indenocarbazole frameworks from 2-alkynylanilines and 2-alkynylbenzaldehydes via BF·OEt-facilitated benzannulation and Friedel-Crafts reaction has been described. This innovative approach accommodates a wide array of functional groups, offering a myriad of diversified carbazole products. Later, postsynthetic modification leads to its C(sp)-H hydroxylation. Furthermore, the photophysical properties of some selected synthesized moieties have been meticulously investigated, promising exciting avenues for further exploration.
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http://dx.doi.org/10.1021/acs.joc.4c01245 | DOI Listing |
J Org Chem
August 2024
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India.
A novel and efficient tandem protocol for the swift synthesis of dihydrobenzo[]indenocarbazole frameworks from 2-alkynylanilines and 2-alkynylbenzaldehydes via BF·OEt-facilitated benzannulation and Friedel-Crafts reaction has been described. This innovative approach accommodates a wide array of functional groups, offering a myriad of diversified carbazole products. Later, postsynthetic modification leads to its C(sp)-H hydroxylation.
View Article and Find Full Text PDFJ Org Chem
December 2021
Department of Applied Chemistry and Biotechnology, Faculty of Engineering, Okayama University of Science, 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan.
A series of 9-amino-10-halophenanthrenes were synthesized through a one-pot process, including dephosphinylative Sonogashira-Hagihara coupling of 2-bromobiphenyls with air-stable phosphinyl ynamines, followed by halonium-promoted [4 + 2] benzannulation of the resulting 2-(aminoethynyl)biphenyls. Nonsubstituted and methyl-substituted 2-bromobiphenyls rapidly underwent the Sonogashira-Hagihara aminoethynylation and the halogenative Friedel-Crafts benzannulation to provide the corresponding amino(halo)phenanthrenes in high yields, while electron-sufficient and -deficient substrates did slowly undergo the former and the latter to result in low yields, respectively. This protocol worked well for the syntheses of highly π-extended aminophenanthrenes and aminobenzonaphthothiophenes with different optical properties.
View Article and Find Full Text PDFJ Org Chem
January 2019
Department of Medicinal and Applied Chemistry , Kaohsiung Medical University, Kaohsiung 807 , Taiwan.
In this work, a concise route for the synthesis of sulfonyl dibenzo-oxabicyclo[3.3.1]nonanes by a two-step route is described, including (i) NaBH/LiCl-mediated reduction of 3-sulfonyl-2-benzylchromen-4-ones and (ii) sequential BF·OEt-mediated intramolecular annulation of the resulting 3-sulfonyl-2-benzylchroman-4-ols.
View Article and Find Full Text PDFChem Commun (Camb)
April 2016
Department of Chemistry, Indian Institute of Science Education & Research, Bhopal, Madhya Pradesh 462066, India.
A novel Rh(ii)/Brønsted acid catalyzed tandem benzannulation of oxindoles with enaldiazo carbonyls led to the formation of valuable 1-hydroxy-2-acylcarbazoles. This reaction is proposed to involve a formal insertion of a rhodium enalcarbenoid into an oxindole sp(2) C-O bond, an oxa-Michael addition, Friedel-Crafts reaction and a semipinacol type 1,2-carbonyl migration.
View Article and Find Full Text PDFOrg Lett
February 2016
Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
BF3·OEt2-mediated one-pot formal (4 + 2) and (5 + 2) stereocontrolled cycloaddition of 4-alkenols 3 and 4 with veratrol affords the respective substituted tetralins 5 and benzosuberans 6 in good yields. The cascade protocol combines a facile double Friedel-Crafts benzannulation of 4-alkenols 3 and 4 (having two electrophilic sites) and veratrol (7a) (having two nucleophilic sites). A plausible mechanism was studied and proposed.
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