Synthesis of 3-aryl-1H-indazoles via iridium-catalysed C–H borylation and Suzuki–Miyaura coupling

Multidirectional Synthesis of Substituted Indazoles via Iridium-Catalyzed C–H Borylation

“…Somewhat surprisingly, borylation of the corresponding N2-protected indazoles also proceeds exclusively Table 1 Borylation of N-protected indazoles at the 3-position even in the presence of relatively bulky benzyl or THP protecting groups at N-2 ( Table 1, entries [8][9][10][11]. The higher reactivity of these isomers was most notably seen with complete borylation of the bulky 3,5-dimethylbenzyl derivative being observed in minutes in contrast to the many hours required for the analogous 1-N protected isomer.…”

Direct Catalytic Functionalization of Indazole Derivatives

“…It was done by monitoring the borylation by GCMS and after consumption of starting material, palladium precatalyst (XPHOS-Pd-G2), aryl halide, potassium phosphate and water were added to the reaction mixture (Scheme 22). [85] Guillaumet and co-workers first reported the direct regioselective method for C-7 arylation of substituted 1H-indazoles (23 a) by reacting with iodoaryl as coupling partner, Pd(OAc) 2 as a catalyst, 1,10-phenanthroline as a ligand and K 2 CO 3 as a base, K 3 PO 4 as an additive in refluxing DMA to obtain C-7 arylated 1Hindazole derivatives 23 b (Scheme 23). [86] The authors showed that 5-nitro-and 6-nitroindazoles produced mixtures of C-3 arylated and C-3/C-7 diarylated products but 4-nitroindazole gave only C-7 arylated product due to steric hindrance between the nitro group at the C-4 position and incoming group at the C-3 position.…”

Chlorophenols in organic synthesis

“…A. Egan и P. M. Burton [26]. Исходными веществами были производные арилгалогенидов (1 экв) и полученный этими же исследовате-лями борированный индазол (1,3 экв).…”

“…A. Egan and M. P. Burton [26] synthesized these compounds. The starting substances were derivatives of arylhalogenides (1 equiv.)…”

“…The results were synthesized compounds 16a and 16b with a yield of 84 % and 76 %, respectively [26].…”