8-oxoheptafulvene vii. Homopolymerization and stereochemistry of adducts of 8-oxoheptafulvene with olefins

✍ Scribed by Noboru Morita; Toyonobu Asao; Yoshio Kitahara

• Book ID: 104214913
• Publisher: Elsevier Science
• Year: 1975
• Tongue: French
• Weight: 215 KB
• Volume: 16
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)75005-2

✦ Synopsis

We have already reported2 that the reactions of 8-oxoheptafulvene with several oleflns and carbonyl compounds afforded the corresponding adducts, their rearrangement products or their decarboxylation products We now studied the homopolymenzatlon, and further reactlons of 8-oxoheptafulvene with several oleflns to fnvestlgate the stereochemistry of the addition reaction because the properties of the ketene moiety may be affected by the cyclic ConJugated unsaturated moiety When the reddlsh solution of 8-oxoheptafulvene (1) obtained by the reaction of 7-cycloheptatrienecarbonyl chloride with tnethylamine in anhydrous n-hexane or ether at room temperature was stirred for 2 hr, the solution became dark brown. After the precipitated tnethylamine hydrochloride was removed, the product was isolated by column chromatography on silica gel using benzene as solvent, and unstable blue crystals (2). mp around 70°C, were obtained in a poor yield (ca. 2%) as only isolable pure product. The compound (2) was determined as 1,3-di(cycloheptatnenylmethanoyloxy)-2-phenylazulene, corresponding to the tetramer of 1, from the following spectral data; molecular formula, C32H2404 (mass spectr obs, 472.1684, calcd, 472.1673),3 UV XEtoH max 244 nm (lo9 E 4.30), 269 (4.32). 302 (4 53). 351 (3.29), 378 (3.08), 620 (2 47). 660sh(2.42), IR (KBr) 1760 cm-', NMR (CDC13) 6 2.78 (t,d, J-5 5, 1.0 Hz, 2H). 5.35 (d,d, J=9 0, 5 5 Hz, 4H), 6.18 (d,m, J=9 0 Hz, 4H), 6.56 (t, J=3 0 hz, 4H), 6.89 (d,d, J-9.5, 9.5 Hz, 2H), 7 l-7.7 (m, 6H) and 7 92 (d, J=9.5 Hz, 2H) The mechanism of the formation of the azulene (g) can be rationalized by two possible pathways depicted below the one is initiated by dfmenzatfon of 1 by the mode of [2 + 21 cycloaddftlon at each ketene group to form cyclobutane-1,3-dlone (3) followed by Cl.73 shift4