Synthesis of 4-Arylselanylpyrazoles Through Cyclocondensation Reaction Using Glycerol as Solvent

Abstract

We describe here a simple method to synthesize 4-arylselanylpyrazoles by reaction of α-arylselanyl-1,3-diketones with arylhydrazines using glycerol as solvent at 60 °C under N2 atmosphere. This is a direct cyclocondensation reaction performed with α-arylselanyl-1,3-diketones and arylhydrazines bearing electron-withdrawing and electron-donating groups affording the corresponding 4-arylselanylpyrazoles in moderate to good yields. ]]>

Glycerol as a Solvent in Organic Synthesis

“…Síntese de benzimidazóis 1,2-dissubstituídos Em uma mesma reação, o glicerol pode ser o solvente e também o agente responsável pela ativação eletrofílica do composto carbonílico, como ocorreu na eaç oà e t eà α-arilselanil-1,3-dicetonas 27 com aril-hidrazinas 28 visando à formação dos respectivos 4-arilselanilpirazóis 29 (Esquema 14). 38 Segundo os autores, o glicerol apresentou maior eficiência para a síntese do heterociclo 29a do que outros solventes verdes testados, como a água, PEG-400 e o bioetanol, assim como em meio livre de solvente. A reação de ciclo-condensação foi realizada em atmosfera de N 2 a 60 °C com iasà α-arilselanil-1,3-dicetonas 27 e arilhidrazinas 28 contendo substituintes elétron-doadores e retiradores ligados ao anel aromático.…”

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].…”