An efficient in situ reduction and cyclization reaction for synthesis of spiro compound derivatives in Fe–H₂O–AcOH medium from nitro compounds

Abstract

An efficient in situ reduction and cyclization reaction for the synthesis of nitrogen‐containing spiro compounds directly form 5‐nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole in Fe–H2O–AcOH medium is reported. 5‐Nitro‐1H‐indazole, 6‐nitro‐1H‐indazole and 5‐nitroindole were first used to synthesize spiro compounds, and this is a novel method for the synthesis of spiro compounds from nitro compounds. The advantages of this reaction are stable reagents, easily available raw materials, wide range of substrates and high yields.

An efficient synthesis of spiroacridinone derivatives from the facile reaction of isatins, dimedone, and 5‐aminoindazole (6‐aminoindazole or 5‐aminoindole)

“…[17] Recently, we used their corresponding nitro compounds to synthesize some new spiro compounds. [18] However, after investigation, we did not find their amino compounds that were used to synthesize spiroacridinone derivatives. Because both acridine and spirooxindole have important biological activities, herein, we wanted to report an efficient process for the synthesis of spiro compounds with both spirooxindole and acridine scaffolds from 5-aminoindazole, 6-aminoindazole, and 5-aminoindole under normal laboratory conditions.…”

“…Interestingly, when the reaction was carried out in the same volume of CH 3 CN and EtOH, the yield could increase to 61% (entry 15). Moreover, with the prolongation of reaction time, the yield increased significantly (entries [16][17][18], and the optimal yield could be obtained when the reaction time was about 7 hours.…”

“…Some pyrazolo[4,3‐ f ]quinoline derivatives were also synthesized by the reactions of aromatic aldehydes, 5‐aminoindazole, and various cyclic 1,3‐dicarbonyl compounds . Recently, we used their corresponding nitro compounds to synthesize some new spiro compounds . However, after investigation, we did not find their amino compounds that were used to synthesize spiroacridinone derivatives.…”