An efficient and green synthesis of multi‐heteroatom heterocycles via a three components reaction in acetic acid/aqueous condition

In this research, the multi‐heteroatom heterocycles were effectively obtained via three components reactions from isatins, 3‐aminopyrazol‐5(4H)‐one, and the different heterocyclic ketones (kojic acid, ethyl 4‐oxopiperidine‐1‐carboxylate, and tetrahydro‐4H‐thiopyran‐4‐one) under acetic acid/aqueous condition for the first time. The advantages of the approach were easy to handle, excellent yields, a wide range of substrates and environmental friendliness. This study provided an alternative synthesis pathway for obtaining multi‐heteroatom heterocycle compounds. In this reserach, the multi‐heteroatom heterocycles (spiro[indoline‐3,4′‐pyrano[3,2‐b]pyrazolo[4,3‐e]pyridine] 4, spiro[indoline‐3,4′‐pyrazolo[3,4‐b][1,6]naphthyridine] 6, and spiro[indoline‐3,4′‐pyrazolo[3,4‐b]thiopyrano[3,4‐e]pyridine] 8 were effectively obtained via three components reactions from isatins, 3‐aminopyrazol‐5(4H)‐one, and the different heterocyclic ketones (kojic acid, ethyl 4‐oxopiperidine‐1‐carboxylate, and tetrahydro‐4H‐thiopyran‐4‐one) under acetic acid/aqueous condition for the first time. The advantages of the approach were easy to handle, excellent yields, a wide range of substrates and environmental friendliness. This study provided an alternative synthesis pathway for obtaining multi‐heteroatom heterocycle compounds.