Efficient Palladium-Catalyzed Cyclotrimerization of Arynes: Synthesis of Triphenylenes
摘要:
Found at the core of many discotic liquid crystals, triphenylenes can now be synthesized efficiently by the palladium-catalyzed trimerization of arynes, including those containing donor and acceptor substituents [Eq. (a); R=OMe, F].
The aryneinsertion into “S═O” bond has been validated recently. This technology is elusively applied to the synthesis of thioethers. In contrast to the reported cases, the reaction described furnished o-aryloxy triarylsulfonium salts, in lieu of thioethers, in good to excellent yields. The reaction is also featured by its exquisite regioselectivity, broad substrate scope, and mild conditions (25 °C)
A transition-metal-free three-phase four-component couplingreaction (3P-4CR) involving KCl, arynes, chloroalkanes and CO2 has been reported for the first time, enabling the incorporation of both chloro and CO2 into an aryne simultaneously. The reactions for the synthesis of different types of o-chloro benzoates can be selectively modulated by the chloroalkane utilized. The corresponding products can
Design and Application of New Imidazolylsulfonate-Based Benzyne Precursor: An Efficient Triflate Alternative
作者:Szabolcs Kovács、Ádám I. Csincsi、Tibor Zs. Nagy、Sándor Boros、Géza Timári、Zoltán Novák
DOI:10.1021/ol300529j
日期:2012.4.20
cycloadditions involving benzyne intermediates. The precursor offers an efficient alternative for generating benzynes compared to widely used ortho TMS triflates under similar reaction conditions. With the utilization of this new precursor, the formation of potentially genotoxic trifluoromethanesulfonate side product is eliminated. The applicability of the new benzyneprecursor was demonstrated in different
Benzynes were generated from o-(trimethylsilyl)phenols using nonafluorobutanesulfonyl fluoride (NfF) by a domino process, i.e., the nonaflation of the phenolic hydroxyl group of o-(trimethylsilyl)phenols by NfF followed by the attack of the produced fluoride ion on the trimethylsilyl group. The generated benzyne immediately underwent various reactions to give polysubstituted benzenes.
o-Trialkylsilylaryl triflates, which are useful aryne precursors, are prepared from o-bromophenols by an efficient, one-pot procedure involving O-silylation, metal-halogen exchange, O- to C-silyl migration, and entrapment of the phenoxide with triflic anhydride.