American Chemical Society
ol049734x_si_002.cif (14.52 kB)

Tetrabromobutatriene:  Completing the Perhalocumulene Series

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posted on 2004-06-24, 00:00 authored by Pei-Hua Liu, Lei Li, Jeffrey A. Webb, Yi Zhang, Nancy S. Goroff
Tetrabromobutatriene, C4Br4, can be prepared directly from dibromobutadiyne by reaction with Br2 at −25 °C in concentrated hexanes solution. The cumulene precipitates out of the reaction mixture as a yellow powder. Under palladium-catalyzed coupling conditions, C4Br4 can undergo allylic rearrangement, giving a mixture of products, including some with butenyne backbones. However, in furan solution, C4Br4 reacts cleanly at its central double bond to give the furan Diels−Alder adduct. Under Suzuki conditions, this adduct reacts at the furan double bond rather than at bromide.