I₂-Promoted site-selective C–C bond cleavage of aryl methyl ketones as C1 synthons for constructing 5-acyl-1H-pyrazolo[3,4-b]pyridines

Abstract

A novel iodine promoted [1 + 3 + 2] cleavage cyclization reaction for the synthesis of 1H-pyrazolo[3,4-b]pyridine from aryl methyl ketones, 5-aminopyrazoles and enaminones has been established. This transition metal-free...

From an Azaarene to the Spine of Fused Bicyclics: Cycloaddition-Induced Scaffold Hopping of 5-Hydroxypyrazoles

“…After a comprehensive consideration of those experimental results, we concluded that our transformation should not be a free radical-driven reaction. According to the present observations and literature existence [70][71][72][73][74] , a possible mechanism has been proposed in Fig. 5d, which was further supported by HRMS detection using acetophenone-D3 as a probe.…”

I2-promoted formal [3 + 1 + 1 + 1] cyclization to construct 5-cyano-1H-pyrazolo[3,4-b]pyridine using malononitrile as a C1 synthon

“…Additional experiments showed that the yield of 4a was decreased upon either increasing or decreasing the temperature from 100 °C (Table 1, entries 5 and 6). The addition of ZnCl 2 , FeCl 3 , HI, TFA and other acids was examined but none of these compounds was found to promote the reaction (Table 1, entries [7][8][9][10][11][12][13][14][15][16].…”

Review of application of the I2 and dimethyl sulfoxide combined reagent system to aryl methyl ketones for diverse transformations

“…According to the research on enaminone, we found that enaminone can also be used as an equivalent of ethylene in this reaction system to give 2,3-diaroyl quinoline products. 59 In addition, this 1,4-dicarbonyl scaffold can be directly condensed with hydrazine hydrates to synthesize the pyridazino[4,5- b ]quinoline skeleton in one pot (Scheme 49). 60…”