A new class of flavonoids bearing macrocyclic polyethers by stereoselective photochemical cycloaddition reaction |
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| Authors: | Hiroki Ishikawa Naohiro Uemura Ryo Taira Kento Sano Yasushi Yoshida Takashi Mino Yoshio Kasashima Masami Sakamoto |
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| Affiliation: | 1. Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan;2. Molecular Chirality Research Center, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan;3. Education Center, Faculty of Creative Engineering, Chiba Institute of Technology, Shibazono, Narashino, Chiba, 275-0023, Japan |
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| Abstract: | A new class of flavonoids bearing cyclic polyethers involving a phenyl ring was conveniently provided by the intramolecular photochemical dimerization of 2-chromonecarboxylic esters. Irradiation of 2-chromonecarboxylate with a polyether tethered at both ends promoted intramolecular [2 + 2] cyclobutane formation leading to 14- to 27-membered cyclic polyethers. The efficiency depended on the substituted position of the phenyl ring, with ortho- and meta-substituted derivatives giving cycloadducts in good chemical yields and quantum efficiencies, whereas the para-derivatives were inert toward photolysis. X-ray crystallographic analysis revealed that the stereochemistry of the macrocyclic cycloadducts exhibited C2-symmetry. |
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| Keywords: | Corresponding author. Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan. photochemical dimerization Chromone Cyclic polyether Cyclobutane |
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