Direct Synthesis of 4‐Organylselanylpyrazoles by Copper‐ Catalyzed One‐Pot Cyclocondensation and CH Bond Selenylation Reactions

Abstract

Abstract:We describe herein an efficient protocol to synthesize selanyl-substituted pyrazoles by cyclocondensation and copper-catalyzedd irect C À H bond selenation reactions.T he products were obtained in moderate to excellent yields by the onepot multicomponent reactions of hydrazines,1 ,3-diketones andd iorganyl diselenides,u sing catalytic amounts of copper bromidea nd bipyridine.T hese reactions tolerated ar ange of substituents in the starting materials and provedt ob ea nefficient methodologyf or combinatorial synthesis of news elenium-containing pyrazoles with potentiala pplications in biological studies.

An environmentally benign and efficient synthesis of 4‐Selanylpyrazoles catalyzed by haloid salts in water

“…tolyl)-1H-pyrazole (3c) [30] Yellow oil. 4.2.5 | 3,5-Dimethyl-1-(4-methoxyphenyl)-4-(phenylselanyl)-1H-pyrazole (3e) [30] White oil.…”

“…1 4.2.7 | 3,5-Dimethyl-1-(4-fluorophenyl)-4-(phenylselanyl)-1H-pyrazole (3 g) [39] Yellow oil. 1 4.2.13 | 1,5-Diphenyl-3-methyl-4-(phenylselanyl)-1H-pyrazole (3o) [30] Yellow oil. 1 4.2.14 | 3-Ethoxy-5-methyl-1-phenyl-4-(phenylselanyl)-1H-pyrazole (3q) [39] White oil.…”

“…[28] In 2015, Jacob and co-workers successfully synthesized 4-arylselanylpyrazoles by the traditional cyclocondensation of α-arylselanyl-1,3-diketones with arylhydrazines. [30] It is interesting because this method is general, efficient, and suitable for a wide variety of starting materials. In the meantime, they demonstrated another way for achieving selanylpyrazoles through a one-pot multicomponent reaction catalyzed by CuBr.…”

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

“…Despite the several number of methodologies describing the transition metal-catalyzed cross-coupling reaction of diorganyl diselenides with (hetero)aryl, alkenyl, and alkynyl halides or pseudo-halides [3], an updated protocol that describe reduced waste generation and atom-economy is desired. In this context, the multicomponent cyclization/direct selanylation is a practical and economical way to incorporate organylselanyl moieties in aryl and heteroaryl compounds avoiding the necessity of pre-functionalization, multistep synthesis and tedious work-up [4–5]. In this context, the preparation of diverse selanylated indoles and imidazopyridines, for example, is widely found in literature [6–7].…”

“…In 2015, Yu and co-workers described one example for the condensation reaction of α-oxo ketene dithioacetal with hydrazine hydrate to produce the 3-methyl-5-methylsulfanyl-4-phenylselanyl-1 H -pyrazole [10]. Our research group described the multicomponent synthesis of 3,5-dimethyl-4-arylselanyl-1 H -pyrazoles catalyzed by copper iodide using DMSO as solvent [4]. More recently, Zora and co-workers reported the one-pot preparation of 4-phenylselanyl-1 H -pyrazoles through reaction of α,β-alkynic hydrazones with phenylselenyl chloride [11].…”