A New Method of Synthesizing Phenalen-1-one: Reduction of 3-Hydroxyphenalen-1-one Using NaBH4 and Lanthanoid Chlorides |
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| Authors: | Tadanobu Sawada Hiroyuki Ishii Toyotoshi Ueda Junji Aoki |
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| Affiliation: | 1. Department of Chemistry, Faculty of Science and Engineering , Meisei University , Hodokubo, Hino, Tokyo, Japan sawada@ge.meisei-u.ac.jp;3. Department of Chemistry, Faculty of Science and Engineering , Meisei University , Hodokubo, Hino, Tokyo, Japan;4. Department of Chemistry, Faculty of Science , Toho University , Miyama, Funabashi, Chiba, Japan |
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| Abstract: | Phenalen-1-one was obtained in considerable yield by reducing 3-hydroxyphenalen-1-one. Most of known preparation methods are not very practical, either because their yields are very poor or because their processes have many steps. This regioselective 1,2-reduction proceeded by the action of NaBH4 and various cations of rare-earth elements and metals. The yields of phenalen-1-one were examined as a function of typical lanthanoids, molar ratios of lanthanoid ions to 3-acetoxy-phenalen-1-one, and differing methods of protecting the hydroxyl group. Lanthanum chloride (LaCl3) gave the greatest yield (45.3%) of phenalen-1-one at molar ratios higher than a third, probably because La3+ ion is a hard acid and coordinates easily to a hard solvent such as methanol. Further, it has the largest ionic radius among all lanthanoid ions. |
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| Keywords: | roman" >α-Enone 3-hydroxyphenalen-1-one lanthanoid salt NaBH4 phenalen-1-one 1,2-reduction |
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