Synthesis of 2-Formylazulene and Its Derivatives by Oxidative Cleavage of 2-Styrylazulenes

Article abstract of DOI:10.1246/bcsj.53.3696

2-Formylazulene and its derivatives were prepared by the oxidative cleavage of styrylazulenes with NaIO4-OsO4. 1,2-Diformyl-, 1,2,3-triformylazulenes, and 5-formylazulene derivative were also synthesized.The reaction of dimethyl 2-methylazulene-1,3-dicarboxylate with p-nitroso-N,N-dimethylaniline in the presence of NaOR (R=Me or Et) gave the corresponding 3-alkoxycarbonyl-2-azulene-1-carboxylic acids followed by hydrolysis with hydrochloric acid to give 3-alkoxycarbonyl-2-formylazulene-1-carboxylic acids.Acetylation of 2-formylazulene-1-carboxylic acids with acetic anhydride gave five membered lactol acetates.