Synthesis 2019; 51(12): 2572-2578
DOI: 10.1055/s-0037-1610866
paper
© Georg Thieme Verlag Stuttgart · New York

Integration of a Four-Step Reaction into One-Pot under the Coexistence­ of Silica-Gel-Supported Acid and Base Reagents: Synthesis of Benzo- and Naphthothiophenes Using NaHSO4/SiO2 and Na2CO3/SiO2

Mamiko Hayakawa
,
Tadashi Aoyama*
Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, Kanda Surugadai, Chiyoda-ku, Tokyo 101-8308, Japan   Email: aoyama.tadashi@nihon-u.ac.jp
,
Kyohei Nakaoka
,
Masayuki Kosuge
,
Akihiko Ouchi
› Author Affiliations
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Publication History

Received: 18 January 2019

Accepted after revision: 04 February 2019

Publication Date:
11 March 2019 (online)


Abstract

A four-step synthesis of benzo- and naphthothiophenes that have biological importance and application in material science was integrated into a one-pot reaction by using silica gel-supported acid and base reagents, NaHSO4/SiO2 and Na2CO3/SiO2. The supported reagents provided acid and base environments on the surface of the supports without neutralization and worked separately in the same medium. The four-step reaction comprises (i) deacetylation of 3-halo-2,4-pentanediones to α-halo ketones, (ii) deacetylation of S-aryl thioacetates to arene­thiols, (iii) coupling of α-halo ketones and arenethiols to give α-sulfanyl ketones, and (iv) cyclization of sulfanyl ketones to benzo- and naphthothiophenes. The steps (i) and (iii) proceeded by Na2CO3/SiO2, and (ii) and (iv) by NaHSO4/SiO2. The four-step reaction proceeded efficiently by introduction of starting materials and reagents in a single reaction vessel. The starting materials were very easy to handle and unpleasant smell of aryl thiols that were used in conventional methods could be avoided. Novel thirty-nine benzo- and naphthothiophenes were synthesized by this method in excellent to fair yields.

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