Diels-alder addition of o-benzoquinones to cyclopentadiene

✍ Scribed by D.D. Chapman; H.S. Wilgus III; J.W. Gates Jr.

• Publisher: Elsevier Science
• Year: 1966
• Tongue: French
• Weight: 194 KB
• Volume: 7
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)70161-4

✦ Synopsis

o-Bensoquinones can behave either as dienes or as dienophiles in Diels-Alder reactions. Usually, however, they react as dienes, particularly if they are substituted. (1) Recently we described(") the isolation of Diels-Alder adducts from cyclopentadiene and three o-bensoquinones. In each case, the quinone functioned as the dienophile to give adducts &R=H, CHs, or Id. The phenylquinone adduct showed strong bands in its IR spectrum at 1720, 1660 and 1605 cm-l, whereas the other two adducts absorbed at 1720, 1675 and 1635 cm-l. These absorptions are consistent with the presence of conjugated and non-conjugated ketones. The NMR spectrum of the phenylquinone adduct was in accord with the proposed structure. Also the adduct was converted to the catechol diacetate 2 on treatment with acetic anhydride and pyridine.