Department of Chemistry, Technion-Israel Institute of Technology Haifa 32000 (Israel), Fax: Int. code +(4)823-3735, e-mail:
Chemistry. 1997 Feb;3(2):208-11. doi: 10.1002/chem.19970030207.
The reaction of hexakis(dibromomethyl)benzene with [(Bu3 P)2 -Ni(COD)] (COD = 1,5-cyclooctadiene) in DMF at 65-70°C yielded a mixture of the title compounds. The mixture was separated by column chromatography to yield hexabromotricyclobutabenzene (3 a) and hexabromohexaradialene (4) in 24 and 16% yields, respectively. (1) H and (13) C NMR spectroscopy suggest that 3 is obtained as the syn-all-trans isomer 3 a, and the symmetric anti-all-trans isomer 3 b is not obtained at all. The X-ray structures of 3 a and 4 are reported. The hexaradialene 4 has a chair conformation, and deviates from planarity by 43.6°. Heat or radical impurities cause the clean transformation of 3 a to 4.
六溴代苯与[(Bu3 P)2 -Ni(COD)]（COD=1,5-环辛二烯）在 DMF 中于 65-70°C反应，生成标题化合物的混合物。通过柱层析将混合物分离，分别以 24%和 16%的收率得到六溴代三环丁苯（3a）和六溴代六螺环二苯（4）。（1）H 和（13）C NMR 光谱表明，3 是以顺式全反式异构体 3a 的形式获得的，而完全没有获得对称反式全反式异构体 3b。报道了 3a 和 4 的 X 射线结构。六螺环二苯 4 具有椅式构象，偏离平面 43.6°。热或自由基杂质会导致 3a 向 4 的干净转化。
