Dicumyl Peroxide as a Methylating Reagent in the Ni-Catalyzed Methylation of Ortho C–H Bonds in Aromatic Amides

Abstract

The direct methylation of ortho C-H bonds in aromatic amides with dicumyl peroxide (DCP) using a nickel complex as the catalyst is reported. The reaction shows a high functional group tolerance and is inhibited by radical scavengers. In reactions of meta-substituted aromatic amides, the reaction proceeds in a highly selective manner at the less hindered C-H bonds.

Well-defined nickel and palladium precatalysts for cross-coupling

“…Other interesting reactions that are relevant to cross-coupling mediated by this precatalyst include the carboxylation of benzyl halides in the presence of elemental Zn (REF. 113) as well as the methylation of aromatic C–H bonds 114 .…”

Cobalt‐Catalyzed C(sp2)−H Methylation by using Dicumyl Peroxide as both the Methylating Reagent and Hydrogen Acceptor

“…reported Ni‐catalyzed C−H methylation with PhMe 3 NI or MeOTs as the electrophilic methylating reagents under basic conditions . Very recently, they reported another Ni‐catalyzed C(sp 2 )−H methylation of arenes under basic conditions employing dicumyl peroxide (DCP) as the methyl source . Cobalt catalysts have great potential in C−H bond functionalization reactions because of their low toxicity, economy, and unique active modes .…”

“…The optimal solvent was found to be α,α,α‐trifluorotoluene (C 6 H 5 CF 3 ) and it afforded 2 a in 73 % yield (entry 5). DTBP was used here for the first time as an efficient methyl source in metal‐catalyzed C−H activation . Next, various cobalt(II) complexes, including CoF 2 , CoCl 2 , CoBr 2 , and Co(OAc) 2 were examined, but all failed to yield 2 a (entries 6–9).…”

“…H/D scrambling was observed when the reaction was performed with an isotopically labeled substrate ([D 5 ]‐ 1 u ), indicating that insertion of cobalt into the C−H bond is reversible (Scheme C). On the basis of above studies and previous reports, a possible catalytic cycle is proposed in Scheme . First, the Co II catalyst is oxidized by DCP through a single‐electron transfer (SET) process giving the Co III species and an alkoxy radical (PhMe 2 CO .…”

Jenseits von Friedel und Crafts: dirigierte Alkylierung von C‐H‐Bindungen in Arenen

“…(1)]. Dicumylperoxid ist ebenfalls ein effizientes Reagens fürd ie Methylierung 8-Aminochinolin-abgeleiteter aromatischer Amide mittels Nickelkatalyse, [122] und die dirigierende Gruppe in 8-Aminochinolinabgeleiteten aromatischen Amiden kann auch selbst unter radikalischen Bedingungen funktionalisiert werden. Darüber hinaus konnte die Reaktion auf die Ethylierung mit Tr iethylaluminium übertragen werden, und luftstabiles Bis(trimethylaluminium)·DABCO (DABCO = 1,4-Diazabicyclo-[2.2.2]octan) konnte anstelle des gefährlicheren Trimethylaluminiums eingesetzt werden.…”