5-Nitroisatin

Preparation

Isatin 30 (14.7 g, 0.1 mol) was added to conc. H2SO4 (121 ml)  cooled to 0 ºC in an ice-salt bath. Fuming HNO3 (4.2 ml) was  added to this, drop by drop, in such a way that temperature should  not rise above 5 ºC. The reaction mixture was allowed to stand for  about 30 minutes and then poured over crushed ice (500 g). A yellow precipitate separated  immediately. The 5-Nitroisatin was filtered and washed with water and air dried to a constant  weight (15 g).  Yield : 85%

Chemical Properties

orange-yellow to orange crystalline powder

Uses

Reactant for preparation of:

• Potential antibacterial and antifungal agents
• spiro[indole-thiazolidinones] as a medicinally important scaffold
• Potential antimycobacterial agents
• Anticonvulsant agents
• Inhibitors of human transglutaminase 2
• Anthelmintic agents
• Anti-human immunodeficiency virus (HIV) agents
• Antimicrobial agents
• Potential antitubercular agents
• Inhibitors of acetylcholinesterase

Definition

ChEBI: 5-Nitroisatin is a member of indoles. It has a role as an anticoronaviral agent.

Synthesis

6146-52-7

611-09-6

The general procedure for the synthesis of 5-nitroindigo red from 5-nitroindole was as follows: a solution of anhydrous acetonitrile (4.0 mL) with 5-nitroindole (0.5 mmol), and iodobenzene diacetate (PIDA, 0.25 mmol) was added sequentially by the addition of a stirrer to a flask that had been pre-dried in an oven. To the reaction mixture, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO, 0.5 mmol) was added under air atmosphere. The reaction mixture was stirred at room temperature until thin layer chromatography (TLC) analysis showed complete conversion of the feedstock. Upon completion of the reaction, the reaction mixture was extracted with ethyl acetate (3 x 10 mL). The organic phases were combined and dried with anhydrous sodium sulfate (Na2SO4) and subsequently concentrated under reduced pressure to give the crude product. Finally, the crude product was purified by silica gel column chromatography.

References

[1] Synthesis, 2007, # 5, p. 693 - 696
[2] Synlett, 2008, # 13, p. 2023 - 2027
[3] Synthetic Communications, 2012, vol. 42, # 23, p. 3419 - 3428
[4] Tetrahedron Letters, 2015, vol. 56, # 46, p. 6385 - 6388