Richard Garth Pews

Hexahalocyclopentadienes—III : Synthesis and Diels-Alder reaction of 1,2,3,4-tetrabromo-5,5-dimethoxycyclopentadiene

Abstract Treatment of hexabromocyclopentadiene ( 1 ) with sodium methoxide in methanol-glyme provides 1,2,3,4-tetrabromo-5,5-dimethoxycyclopentadiene ( 6 ). The reactivity of this new diene in the Diels-Alder reaction has been determined with a number of dienophiles. The greater reactivity of ketal 6 towards maleic anhydride compared to cyclopentadiene suggests that 6 behaves as an electron-rich diene in the Diels-Alder reaction.

Hexabromocyclopentadiene V. The Diels-Alder reaction of hexabromocyclopentadiene

Abstract The reactivity of hexabromocyclopentadiene (1) as a diene in the Diels-Alder reaction has been determined with a number of dienophiles. The results of the present study show that 1 behaves as an electron-poor diene in that cyclopentadiene is a more reactive dienophile than maleic anhydride. Qualitatively, 1 has been found to be a less reactive diene than hexachlorocyclopentadiene. Several new Diels-Alder adducts of 5,5-dibromo-1,2,3,4-tetrachlorocyclopentadiene are also reported.