An Efficient Synthesis of 1′,7′,8′,9′‐Tetrahydrospiro[indoline‐3,4′‐pyrazolo[3,4‐b]quinoline]‐2,5′(6′H)‐dione Derivatives in Aqueous Medium

Abstract

An efficient and green reactions of isatins, 3‐amine‐1H‐pyrazole (5‐methyl‐1H‐pyrazol‐3‐amine) and 1,3‐diketone in aqueous medium for the synthesis of novel 1′,7′,8′,9′‐tetrahydrospiro[indoline‐3,4′‐pyrazolo[3,4‐b]quinoline]‐2,5′(6′H)‐dione derivatives were reported in this research. The advantages of this reaction are simple operation, mild‐reaction conditions, wide scope substrate, high yields, and friendly environment. The products were confirmed by IR, 1H NMR, 13C NMR, and HRMS.

Green Synthesis of Pyrazoles: Recent Developments in Aqueous Methods

“…In 2018, Rong and co-workers synthesized spiro[indoline-3,4′-pyrazolo [3,4-b]quinoline]-2,5′(6′H)-diones 14 using isatins, 3-aminopyrazole, and cyclohexane-1,3-dione or dimedone as reactants with H 2 O/AcOH (4:1) as the solvent system at 90 °C for 5-7 h (Scheme 8). 44 The use of lower temperature was unsuccessful and the use of a single solvent, such as water or acetone gave poor yields. In 2018, Atmakur and co-workers reported the reaction of arylaldehydes and 1,3-disubstituted pyrazolones in refluxing water for 30 min followed by the addition of [bis(acetoxy)iodo]benzene (BAIB) and stirring for 5 min at room temperature to give spirofuropyrazoles 16 (Scheme 9).…”

Organocatalyzed Synthesis of Functionalized Quinolines

“…Guangzhou et al [40] studied am ixture of water and acetic acid catalytic synthesis of quinoline derivativesa nd the strategy was ag reen protocolw ith high yield in the same year (Scheme 24).…”