| 摘要 |
PURPOSE:To obtain the titled compound useful for an intermediate for mecicines, by subjecting a 2-alkoxy-, 2-acetyloxy- or 2-allylsiloxybutadiene and 4- vinylpyridine to the Diels-Alder reaction and treating the cyclization product with an acid. CONSTITUTION:A compound expressed by formula I (R is methyl, ethyl, n-butyl, trimethylsilyl, tert-butyldimethylsilyl or acetyl) and a compound expressed by formula V are subjected to the Diels-Alder reaction in or without a solvent, e.g. benzene, chloroform or methylene chloride, etc., as necessary, in the presence of a Lewis acid or/and a polymerization inhibitor, e.g. phenyl-alpha-naphthylamine, hydroquinone, etc., at 0-250 deg.C, preferably 150-200 deg.C to afford a compound expressed by formula VI, which is then hydrolyzed with an acid, e.g. hydrochloric acid, acetic acid or trifluoroacetic acid, etc., to give the aimed compound expressed by formula II particularly useful as an intermediate for a cardiotonic agent (compound expressed by formula III).
|
