RESUMO
An "on water" palladium-catalyzed direct (hetero)arylation of 2H-pyrazolo[3,4-b]pyridines has been developed. The reactions proceeds smoothly with at low catalytic loading at low temperature providing the C3 (hetero)arylated products in good to excellent isolated yields. Free NH 3-arylated 7-azaindazoles were also prepared by simple cleavage of the N-protected groups.
RESUMO
The first palladium-catalyzed oxidative alkenylation of (1H)- and (2H)-indazole derivatives with various olefins is described. The use of Pd(OAc)2 as the catalyst and Ag2CO3 as the oxidant promoted the selective C3-monoalkenylation of (1H)-indazoles and (2H)-indazoles, affording the desired products in good yields. An original oxidative C7-alkenylation of 3-substituted (1H)-indazoles was also developed. The oxidative alkenylation of (1H)-indazole was successfully applied to the total synthesis of the drug candidate gamendazole in a step- and atom-economical fashion.
Assuntos
Indazóis/síntese química , Paládio/química , Alcenos/química , Catálise , Indazóis/química , Estrutura Molecular , Oxidantes/química , Oxirredução , EstereoisomerismoRESUMO
A novel direct C7-arylation of indazoles with iodoaryls is described using Pd(OAc)2 as catalyst, 1,10-phenanthroline as ligand, and K2CO3 as base in refluxing DMA. Direct C7-arylation of 3-substituted 1H-indazole containing an EWG on the arene ring gave the expected products in good isolated yields. In addition, a one-pot Suzuki-Miyaura/arylation procedure leading to C3,C7-diarylated indazoles has been developed.
