Facile Three‐Component Synthesis of Macrocyclane‐Fused Pyrazolo[3,4‐b]pyridine Derivatives

Abstract

A series of new functionalized macrocyclane-fused pyrazolo [3,4-b]pyridine derivatives with an aryl group at the 2-position of the pyridine nucleus have been synthesized by microwave-assisted three-component reactions of aldehydes, aminopyrazole and cycloketones in HOAc using 1.0 equiv. of TFA as a promoter. The procedure is facile, avoiding time-

5-(4-Chlorophenyl)-1-methyl-3-phenyl-3,6,8,9-tetrahydropyrazolo[3,4-b]thiopyrano[4,3-d]pyridine

“…The pyrazolo [3,4-b]pyridine system represents the core skeleton of a pharmaceutically important class of heterocyclic compounds that possess a broad range of biological activity, see: Beutner et al (2009); Hamblin et al (2008); Jiang et al (2011); Lynck et al (1988); Manetti et al (2005); Meiners & Salama (1982); Revesz et al (2006); Witherington et al (2003). For related structures, see: Chebanov et al (2007); Lee & Park (2009); Quiroga et al (2001).…”

Microwave-assisted one-pot synthesis in water of carbonylpyrazolo[3,4-b]pyridine derivatives catalyzed by InCl3 and sonochemical assisted condensation with aldehydes to obtain new chalcone derivatives containing the pyrazolopyridinic moiety

“…[6][7][8][9][10][11][12][13][14] Due to their attractive pharmacological properties, pyrazolo [3,4-b]pyridines have attracted the attention of chemists who have researched ways to obtain the desired properties through different synthetic strategies. The most common reactions include: (a) condensation of pyrazole-5-amine derivatives and activated carbonyl groups; [15][16][17] (b) reaction of 5-aminopyrazoles, 1,3-dicarbonyl derivatives or equivalents and aldehydes through of Hantzsch-type reaction; [18][19][20] (c) through Povarov-type [4 + 2], cycloaddition between 5-aminopyrazoles, aromatic aldehydes, and cycloalkanones in acetic acid; 21 methylene ketones such as acetone or acetophenones with potassium hydroxide as basic catalyst. [22][23][24] The methods described in the literature presents several disadvantages such as the use of toxic solvents for the environment, long reaction times, several steps of synthesis, these contradict the current trends of green chemistry, 25 as a result of the importance that presents these heterocycles in the medicinal eld, different researchers have designed environmentally friendly and efficient synthetic routes, for example have used water as solvent under microwave irradiation (MWI) using catalysts organic or inorganic.…”

Microwave‐Assisted Three‐Component Reactions Leading to Pyrano‐Fused Pyrazolo[3,4‐b]pyridines

“…In our previous report, we synthesized polyfunctionalized macrocyclane‐fused pyrazolopyridines through the Povarov reaction of macrocycloketones in the presence of TFA . As a continuation of our efforts to further investigate the substrate scope of the reaction system, in this paper tetrahydropyran‐4‐one 2 was subjected to this reaction.…”