Cobalt schiff base complex promoted retro-claisen reaction of 1-(2-hydroxyphenyl)-3-phenyl-1,3-propanediones and flavone formation

✍ Scribed by Akira Nishinaga; Kazushige Maruyama; Hiroyuki Ando; Ryoji Sato; Takahiro Mashino; Inada Akira; Nakanishi Tsutomu

• Publisher: Elsevier Science
• Year: 1990
• Tongue: French
• Weight: 279 KB
• Volume: 31
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)94724-5

✦ Synopsis

Co(salpr) promotes the conversion of 1-(2-hydroxyphenyl)-3-phenyl-1,3_propanediones to retro-Claisen reaction products and flavones in methanol under oxygen. Base catalysis by Co(salpr)(OH) produced in situ is responsible for the reaction. Cobalt Schiff base complexes [Co(SB)] are very interesting because of their characteristic behavior as artificial oxidoreductases: they catalyze dioxygenation in aprotic solvents, monooxygenation in protic solvents, l-5 and dehydrogenation of alcohols, 4 hydrazones, 6 and amines. 7,S The important key step in these model oxidoreductase reactions is the formation of oxygen sensitive substrate anion cobalt(II1) complex intermediates resulting from an acid-base reaction of ColI1 (SB)(OH) with the substrates.g'10 Recently, we have shown the first direct evidence for the base catalysis of Co"' (SB)(OH) in the conver-