Chemoselective Cu-catalyzed synthesis of diverse <i>N</i>-arylindole carboxamides, β-oxo amides and <i>N</i>-arylindole-3-carbonitriles using diaryliodonium salts
Chemoselective copper-catalyzed synthesis of diverse N-arylindole-3-carboxamides, β-oxo amides and N-arylindole-3-carbonitriles from readily accessible indole-3-carbonitriles, α-cyano ketones and diaryliodonium salts has been developed. Diverse N-arylindole-3-carboxamides and β-oxo amides were successfully achieved in high yields under copper-catalyzed neutral reaction conditions, and the addition
one-pot sequence of N-alkylation, saponification and methoxyamidation, and final intramolecular oxidative C–N bond formation. The underpinning of the strategy entails Pd(OAc)2/Cu(OAc)2-mediated oxidative C(sp2)–C(sp2) bond formation and I(III)-mediated oxidative C(sp2)–N bond formation.
The treatment of 6-chloroindolo[3,2-c]quinoline 6 with NaH–MeI led to methylation at N-11, forming 8, while the reaction of 6 with MeI with heating gave the corresponding 5-methylated quinolinium salt whose SNAr with water smoothly proceeded to form 5-methylindolo[3,2-c]quinolin-6-one 3b. The amination reactivity at the C-6 was assigned in the order of 6 > 11-methylated 8.
catalyzed intramolecular dual C–Hactivation to construct indoloquinolinone derivatives under mild conditions with dioxygen as the sole oxidant. It was found that adding LA such as Sc3+ to Pd(OAc)2 sharply improved its catalytic efficiency, whereas Pd(OAc)2 alone was very sluggish. The activity improvement was attributed to the linkage of the Sc3+ cation to the Pd(II) species through a diacetate bridge that