Palladium-catalyzed, copper-mediated construction of benzene rings from the reactions of indoles with in situ generated enones

Abstract

Construction of the benzene ring was efficiently realized through a palladium(ii)-catalyzed, copper(ii)-mediated domino dehydrochlorination/alkenylation/cycloaddition–oxidation sequence.

Regioselective Direct C‐Alkenylation of Indoles

“…The yields of the obtained carbazoles are not particularly outstanding and the procedure only allows for the introduction of the same substituent in the molecular framework. Following the same strategy, 1,3‐diketocarbazoles can be prepared by Pd(OAc) 2 catalyzed reaction of indoles with β‐chloro arylketones . Under the devised reaction conditions the chlorinated ketones are converted into vinylaryl ketones which act as the alkenylating reactants in the whole process.…”

“…Following the same strategy, 1,3-diketocarbazoles can be prepared by Pd(OAc) 2 catalyzedr eaction of indoles with b-chloro arylketones. [31] Under the devised reactionc onditions the chlorinatedk etones are converted into vinylaryl ketones whicha ct as the alkenylating reactants in the whole process. Upon changingt he reactionc onditions (PdCl 2 ,P Ph 3 )t he Diels-Alder process after the monoalkenylation is no longero perative.…”

Palladium-catalyzed oxidative annulation of in situ generated enones to pyrroles: a concise route to functionalized indoles

“…Under acid, 15 iodine, 16 or organo-catalysis 17 conditions pyrrole substrates usually underwent Friedel-Crafts alkylation with α,β-60 unsaturated ketones (enones) (Scheme 1b). Intrigued by the advantages of using in-situ generated enones as the olefin sources for carbon-carbon bond formation, [18][19][20][21] we reasonably envisioned the oxidative annulation reactions of β-chloroalkyl ketones to pyrroles. Herein, we report direct synthesis of indoles from 65 pyrroles and 3-chloropropiophenones in a one-shot style (Scheme 1c).…”

Annulative π‐Extension (APEX): Rapid Access to Fused Arenes, Heteroarenes, and Nanographenes

“…However, as the polymerization of vinyl compounds competes with the APEX reaction, 10 equivalents of the π‐extending reagent are required to obtain 1,3‐diarolylcarbazoles 131 in good yields. One year later, the group of Yu overcame this issue by using enones generated in situ from 3‐chloropropiophenone 132 derivatives (Scheme , top) . This reaction shows broad substrate scope in both the indole and enone.…”