Palladium-assisted "aromatic metamorphosis" of dibenzothiophenes into triphenylenes.
Two new palladium-catalyzed reactions of aromatic sulfur compounds enabled the conversion of dibenzothiophenes into triphenylenes in four steps. This transformation of one aromatic framework into another consists of 1) 4-chlorobutylation of the dibenzothiophene to form the corresponding sulfonium salt, 2) palladium-catalyzed arylative ring opening of the sulfonium salt with a sodium tetraarylborate, 3) an intramolecular S(N)2 reaction to form a teraryl sulfonium salt, and 4) palladium-catalyzed intramolecular C-S/C-H coupling through electrophilic palladation. Symmetrical as well as unsymmetrical triphenylenes of interest were synthesized in a tailor-made fashion in satisfactory overall yields.
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan).
Dhananjayan
D
Vasu
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan). yori@kuchem.kyoto-u.ac.jp.|ACT-C, JST, Sakyo-ku, Kyoto 606-8502 (Japan). yori@kuchem.kyoto-u.ac.jp.
Hideki
H
Yorimitsu
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan).
Atsuhiro
A
Osuka
CH arylation; CS cleavage; cross-coupling; palladium; sulfur