Tetrabromobutatriene: completing the perhalocumulene series.
[structure: see text] Tetrabromobutatriene, C(4)Br(4), can be prepared directly from dibromobutadiyne by reaction with Br(2) at -25 degrees C in concentrated hexanes solution. The cumulene precipitates out of the reaction mixture as a yellow powder. Under palladium-catalyzed coupling conditions, C(4)Br(4) can undergo allylic rearrangement, giving a mixture of products, including some with butenyne backbones. However, in furan solution, C(4)Br(4) 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.
Liu
Pei-Hua
PH
Department of Chemistry, State University of New York, Stony Brook, New York 11794-3400, USA.
Li
Lei
L
Webb
Jeffrey A
JA
Zhang
Yi
Y
Goroff
Nancy S
NS