120233-65-0Relevant academic research and scientific papers
Selective Borylation of [4]Helicene
Ne?as, David,Kaiser, Reinhard P.,Ul?, Jan
, p. 5647 - 5652 (2016)
The Ir-catalyzed borylation of [4]helicene under different reaction conditions was studied for the first time. The results indicate that monoborylation proceeds to give a mixture of 2- and 3-borylated products in good yields (up to 74 % isolated yield). It was possible to shift the selectivity in favor of the 3-borylated product by using sterically demanding ligands. The monoborylated [4]helicenes were further arylated by using a Suzuki–Miyaura cross-coupling or oxidized to the corresponding phenols in very good yields.
Interconversions of aryl radicals by 1,4-shifts of hydrogen atoms. A synthesis of benzo[a]corannulene
Peng, Lingqing,Scott, Lawrence T.
, p. 16518 - 16521 (2005)
Aryl radicals generated ortho to aryl substituents by flash vacuum pyrolysis (FVP) of the corresponding aryl chlorides are shown to be capable of transferring hydrogen atoms between the ortho and ortho' positions (1,4-shifts of hydrogen atoms). In the examples described here, the rearranged aryl radicals are trapped by subsequent radical cyclization reactions. For example, FVP of 2-(ochlorophenyl)-benzo[c]phenanthrene gives 1-phenylbenzo[ghi]fluoranthene as the major product by homolysis of the C-CI bond, 1,4-shift of a hydrogen atom out of the sterically congested cove region to the radical center, cyclization of the rearranged radical, and rearomatization of the molecule by loss of the other cove region hydrogen. In a control experiment run under the same conditions, FVP of 2-phenylbenzo[c]phenanthrene, which lacks a radical precursor, gave primarily recovered starting material. When the FVP was repeated using 2-(2,6-dichlorophenyl)benzo[c]phenanthrene as the starting material, benzo[a]corannulene was obtained as the major product, presumably by the same cascade of events to produce 1-(o-chlorophenyl)benzo[ghi]-fluoranthene, which then suffers a second radical cyclization spontaneously under the high-temperature conditions to give the geodesic polyarene.
Highly efficient fluorine-promoted intramolecular condensation of benzo[c]phenanthrene: A new prospective on direct fullerene synthesis
Amsharov, Konstantin Yu.,Kabdulov, Mikhail A.,Jansen, Martin
experimental part, p. 6328 - 6335 (2011/03/19)
Various functional groups have been tested as alternative promoters of the intramolecular condensation of benzo-[c]phenanthrene under flash vacuum pyrolysis conditions. Methyl and fluorine functionalization were found to be promising approaches. Unexpectedly high selectivity was observed in the cyclization of fluorinated benzo[c]phenanthrenes. The mechanism for the condensation reaction and the advantages of fluorine as a promoter for the rational synthesis of fullerenes are discussed. Wiley-VCH Verlag GmbH & Co. KGaA.
