Cu^II‐Promoted Aerobic Cascade Reactions of 2‐Alkynylanilines with Methyl Perfluoroalk‐2‐ynoates: En Route to 4‐Carbonyl‐2‐perfluoroalkylquinolines

Abstract

Using air as the oxygen source, 4‐carbonyl‐2‐perfluoroalkylquinolines were prepared in good to excellent yields, from readily available 2‐alkynylanilines and methyl perfluoroalk‐2‐ynoates through a CuII‐promoted sequential process that omits the isolation of the enamine intermediates. The reaction tolerates several useful functionalities including ether, ester and chloro substituents.

Direct Synthesis of Quinolines via Co(III)-Catalyzed and DMSO-Involved C–H Activation/Cyclization of Anilines with Alkynes

“…Alternatively, a recently popular C–H bond functionalization strategy has emerged as one of the most powerful tools for the step- and atom-economical construction of quinoline framework. Indeed, numerous versatile protocols have been disclosed by second-row transition metals such as Rh, Ru, Pd, Au, Ag, etc . Despite this compelling progress, it would be ideal to directly build the quinoline motif via earth-abundant and inexpensive first row transition-metal-catalyzed C–H bond functionalization strategy in view of green and sustainable chemistry.…”

Annulation of 2‐Alkynylanilines: The Versatile Chemical Compounds

“…Cu(II)‐catalyzed oxidative cyclization of compound 8 with methyl perfluoroalk‐2‐ynoates 80 led to the construction of 4‐carbonyl‐2‐perfluoroalkylquinolines 85 (Scheme 27). The presumably mechanism includes formation of enamine 81 through Michael addition of aniline 8 to alkyne 80 , cyclization reaction to give intermediate 82 via nucleophilic attack of the carbon to CuBr 2 , air‐assisted oxidation to achieve peroxycopper(III) 83 , rearrangement of the latter, and finally cleavage of the peroxycopper(II) complex 85 [78] . By replacing alkyne 80 with α,β‐ynones, some other substituted quinolines are prepared [79]…”

“…[77] Cu(II)-catalyzed oxidative cyclization of compound 8 with methyl perfluoroalk- peroxycopper(III) 83, rearrangement of the latter, and finally cleavage of the peroxycopper(II) complex 85. [78] By replacing alkyne 80 with α,β-ynones, some other substituted quinolines are prepared. [79] 4-(1H-Indol-3-yl)quinolines 89 were prepared through conjugate addition of sodium iodide to β-(2-aminophenyl)α,β-ynones 57 to achieve intermediate 86, followed by Pdcatalyzed cyclization of the adduct 87 with 2-alkynyl-trifluor-oacetanilides 8 a-f (Scheme 28) passing from intermediate 88.…”

Synthesis of Organofluoro Compounds Using Methyl Perfluoroalk-2-ynoates as Building Blocks

“…[32] The sole formation of the product 56 could be explained by the highly regioselective coordination of the base-activated amino group in 55 with the more electrophilic carbon atom of the triple bond in 1 (Scheme 20).…”

“…Since 2‐alkynylanilines 55 are widely used synthons that can be easily prepared by the classical Pd/Cu‐catalyzed Sonogashira reaction with 2‐iodoanilines and terminal alkynes,31 we developed Cu(II)‐promoted cascade reactions of 2‐alkynylanilines 55 with methyl perfluoroalk‐2‐ynoates 1 in methanol at room temperature under air to synthesize 4‐carbonyl‐2‐perfluoroalkylquinolines 56 (Scheme ) 32…”