Rhodium(III)-Catalyzed Site-Selective C–H Alkylation and Arylation of Pyridones Using Organoboron Reagents

Abstract

In this study we developed a method for the pyridine-directed, rhodium-catalyzed, site-selective C-H alkylation and arylation of pyridones using commercially available trifluoroborate reagents. This simple and versatile transformation proceeded smoothly under relatively mild conditions with perfect site selectivity. The coupling groups in the boron reagents can be extended to primary alkyl, benzyl, and cycloalkyl. Moreover, direct C-H arylation products could also be obtained under similar conditions.

Rh(III)-Catalyzed C–H Bond Activation for the Construction of Heterocycles with sp3-Carbon Centers

“…In recent years, our group has been devoted to developing some highly efficient synthetic strategies to extend our heterocyclic compounds library for the screening of biologically active lead compounds [75−85]. In 2017, we built a novel isoindolone scaffold bearing a quaternary carbon via Rh(III)-catalyzed C−H bond cleavage and subsequent [4 + 1] cyclization tandem reactions between In recent years, our group has been devoted to developing some highly efficient synthetic strategies to extend our heterocyclic compounds library for the screening of biologically active lead compounds [75][76][77][78][79][80][81][82][83][84][85]. In 2017, we built a novel isoindolone scaffold bearing a quaternary carbon via Rh(III)-catalyzed C−H bond cleavage and subsequent [4 + 1] cyclization tandem reactions between benzamides and propargyl alcohols (Scheme 13) [76].…”

Transition Metal Mediated C–H Activation of 2‐Pyrones, 2‐Pyridones, 2‐Coumarins and 2‐Quinolones

“…Liu described the 2‐pyridine‐directed, rhodium‐catalysed C–H alkylation of 2‐pyridones with a wide variety of alkyl and cycloalkyl trifluoroborate reagents (Scheme ) . The reaction proceeded with excellent regioselectivity and functional group tolerance.…”

“…Direct arylation at C-6 could also be achieved using Liu's conditions although higher temperatures were required (Scheme 27). [42] Scheme 27. Direct arylation of 2-pyridones via C-H activation.…”

Cp*Rh(III)‐Catalyzed Directed C−H Methylation and Arylation of Quinoline N‐Oxides at the C‐8 Position

“…[38] In addition, Larionov developed the palladium-catalyzed C8 arylation and selective homocoupling of quinoline N-oxides. [45][46][47][48][49] Inspired by the previous work by Li [50] and our groups, [51] we disclose a Rh(III)-catalyzed C8 functionalization of quinoline N-oxides with organoboron reagents (Scheme 2). [40][41][42][43][44] However, related alkylation at the C8 position of quinoline N-oxides with organo-boron reagents remains unexplored.…”

“…[40][41][42][43][44] However, related alkylation at the C8 position of quinoline N-oxides with organo -1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 boron reagents remains unexplored. [45][46][47][48][49] Inspired by the previous work by Li [50] and our groups, [51] we disclose a Rh(III)-catalyzed C8 functionalization of quinoline N-oxides with organoboron reagents (Scheme 2).…”