Synthesis and Optical Properties of <i>N</i>-Arylnaphtho- and Anthra[2,3-<i>d</i>]oxazol-2-amines

Oxazole, a versatile and significant heteroarene, serves as a bridge between synthetic organic chemistry and applications in the medicinal, pharmaceutical, and industrial fields. Polycyclic aromatic compounds with amino groups substituted at the 2-position of an oxazole, such as 2-aminonaphthoxazole...

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Bibliographic Details
Main Authors: Yuki Murata, Masato Kawakubo, Ayumi Maruyama, Mio Matsumura, Shuji Yasuike
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/2/319
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Summary:Oxazole, a versatile and significant heteroarene, serves as a bridge between synthetic organic chemistry and applications in the medicinal, pharmaceutical, and industrial fields. Polycyclic aromatic compounds with amino groups substituted at the 2-position of an oxazole, such as 2-aminonaphthoxazoles, are expected to be functional probes, but their synthetic methods are extremely limited. Herein, we describe electrochemical reactions of 3-amino-2-naphthol or 3-amino-2-anthracenol and isothiocyanates in DMSO, using a graphite electrode as an anode and a platinum electrode as a cathode in the presence of potassium iodide (KI), which afford <i>N</i>-arylnaphtho- and <i>N</i>-arylanthra[2,3-<i>d</i>]oxazol-2-amines via cyclodesulfurization. This reaction is the first example of synthesis of 2-aminoxazole-based polycyclic compounds using an electrochemical reaction. An examination of the spectroscopic properties of polycyclic oxazoles revealed that the λ<sub>abs</sub> value of the tetracyclic oxazoles was redshifted relative to that of the tricyclic oxazoles. Moreover, synthesized naphthalene/anthracene-fused tricyclic and tetracyclic oxazoles exhibited extended π-conjugated skeletons and fluoresced in the 340–430 nm region in chloroform.
ISSN:1420-3049