An intramolecular arene-triflate coupling reaction for the regiospecific synthesis of substituted benzofluoranthenes
摘要:
An intramolecular triflate-arene coupling reaction mediated by bis(triphenylphosphine)palladium(II) chloride has been developed for the synthesis of each of the isomeric benzofluoranthenes. This reaction, which results in formation of a new five-membered ring, proceeds in highest yield when performed using 0.1 equiv of the palladium catalyst, 3 equiv of lithium chloride, and 1.2 equiv of 1,8-diazabicyclo[5.4.0]undec-7-ene in N,N-dimethylformamide at 140-degrees-C. The biaryl precursors needed for the coupling reaction can be prepared by [1,2-bis(diphenylphosphino)ethane]nickel(II) chloride catalyzed coupling of an aryl bromide with an [o-(methoxymethoxy)aryl]magnesium bromide (prepared by ortho-lithiation of an aryl methoxymethyl ether followed by transmetalation with magnesium bromide). Using this procedure benzo[a]fluoranthene, benzo[b]fluoranthene, benzo[j]fluoranthene, and benzo[k]fluoranthene were prepared in yields of 84%, 85%, 93%, and 64%, respectively. The reaction to prepare benzo[j]fluoranthene was regiospecific and afforded none of the six-membered ring product, perylene. The method was extended to the preparation of benzo[b]fluoranthene (BbF) derivatives with fluoro or methoxy groups on the benzo ring. The cyclization of compounds possessing a methoxy group on the same ring as the triflate required the addition of 0.4 equiv of triphenylphosphine to the reaction mixture. Strategies are reported for the regiospecific preparation of 4-, 5-, 6-, and 7-substituted benzo[b]fluoranthenes. Evidence is presented which suggests the intermediacy of radicals in the oxidative-addition of aryl triflates to the palladium catalyst.
Regioselective Activation of a Sterically More Hindered C−C Bond of Biphenylenes Using an Alkene as Both a Directing Group and a Reaction Moiety
作者:Hideaki Takano、Takeharu Ito、Kyalo Stephen Kanyiva、Takanori Shibata
DOI:10.1002/chem.201804044
日期:2018.10.12
The Rh‐catalyzed intramolecular reaction of 1‐(2‐vinylaryl)‐substituted biphenylenes was used to construct a dihydrobenzo[b]fluoranthene skeleton. This transformation was achieved by regioselective C−C bond cleavage of a sterically more hindered biphenylene site by using alkene as both a directing group and a reaction moiety. Furthermore, we measured and analyzed the photophysical properties of the
1-(2-乙烯基芳基)取代的联苯的Rh催化的分子内反应被用来构建二氢苯并[ b ]荧蒽骨架。通过使用烯烃作为导向基团和反应部分,通过在空间上更受阻的联苯部位的区域选择性C-C键断裂实现了该转化。此外,我们测量并分析了新型多环稠合化合物的光物理性质。
Rice, Joseph E.; Cai, Zhen-Wei, Tetrahedron Letters, 1992, vol. 33, # 13, p. 1663 - 1678
作者:Rice, Joseph E.、Cai, Zhen-Wei
DOI:——
日期:——
AMIN, SHANTU;HUIE, KEITH;HUSSAIN, NALBAND;BALANIKAS, G.;CARMELLA, S. G.;H+, J. ORG. CHEM., 1986, 51, N 8, 1206-1211
作者:AMIN, SHANTU、HUIE, KEITH、HUSSAIN, NALBAND、BALANIKAS, G.、CARMELLA, S. G.、H+