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

An efficient in situ reduction and cyclization reaction for the synthesis of nitrogen‐containing spiro compounds directly form 5‐nitro‐1 H ‐indazole, 6‐nitro‐1 H ‐indazole and 5‐nitroindole in Fe–H 2 O–AcOH medium is reported. 5‐Nitro‐1 H ‐indazole, 6‐nitro‐1 H ‐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.