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Synlett 2007(8): 1255-1256  
DOI: 10.1055/s-2007-977413
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Novel One-Pot Synthesis of 4-Substituted 1,2,4-Triazolidine-3,5-diones

Shadpour Mallakpour*, Zahra Rafiee
Organic Polymer Chemistry Research Laboratory, College of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran
Fax: +98(311)3912350; e-Mail: mallak@cc.iutac.ir;
Further Information

Publication History

Received 25 November 2006
Publication Date:
03 April 2007 (online)

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Abstract

A simple and one-pot pathway for the preparation of 4-substituted phenyl derivatives of triazolidindiones (urazoles), ­starting from aniline derivatives is reported. In these methods aniline derivatives were reacted with ethyl chloroformate, to give the corresponding carbamate derivatives. In the second step ­semicarbazide derivatives were prepared from these carbamates by reaction with ethyl carbazide. The cyclization reactions of the ­corresponding semicarbazides furnished triazolidindiones. All reactions were performed in one vessel without the isolation of reaction intermediates, such as carbamates and semicarbazides, and the final products were isolated in good yields.

Key words

urazole derivatives - heterocyclic compounds - semi­carbazide - carbamate - one-pot reaction

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Mallakpour, S.; Rafiee, Z., unpublished results.

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One-Pot Preparation of 4-(2-Nitrophenyl)-1,2,4-triazolidine-3,5-dione ( 3d): 2-Nitrophenyl aniline (0.100 g, 0.0724 mmol) in acetone (5 mL) was cooled to 0 °C and Et3N (0.07 mL, 0.0724 mmol) in acetone (1 mL) was added. The reaction mixture was stirred for a further 1 h and then a solution of ethyl chloroformate (0.078 g, 0.0724 mmol) in acetone (2 mL) was added at 0 °C. The resulting reaction mixture was stirred for 1 h at the same temperature and then a solution ethyl carbazate (0.075 g, 0.0724 mmol) in acetone (2 mL) was added dropwise. Finally the reaction mixture was refluxed for 10 h. The solid was collected by filtration and recrystallized from distilled H2O. IR (KBr): 3200 (s, NH), 1780 (m, C=O), 1700 (s, C=O), 1500 (s, NO2), 1350 (s, NO2) cm-1. MS: m/z = 222 [M+]. 1H NMR (500 MHz, DMSO-d 6): δ = 7.86-7.88 (m, 2 H, ArH), 8.32-8.34 (m, 2 H, ArH), 10.72 (s, 2 H, NH).

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4-(3-Nitrophenyl)-1,2,4-triazolidine-3,5-dione ( 3e): IR (KBr): 3200 (s, NH), 1770 (m, C=O), 1679 (s, C=O), 1500 (s, NO2), 1350 (s, NO2) cm-1. MS: m/z = 222 [M+]. 1H NMR (500 MHz, DMSO-d 6): δ = 7.68-7.72 (m, 2 H, ArH), 7.86-7.90 (m, 1 H, ArH), 8.13-8.15 (dd, J 1 = 8.08 Hz, J 2 = 1.18 Hz, 1 H, ArH), 10.83 (s, 2 H, NH).
4-(2-Chloro-4-nitrophenyl)-1,2,4-triazolidine-3,5-dione ( 3g): IR (KBr): 3230 (s, NH), 1780 (m, C=O), 1690 (s, C=O), 1500 (s, NO2), 1340 (s, NO2), 780 (s, CCl) cm-1. MS: m/z = 257 [M+]. 1H NMR (500 MHz, DMSO-d 6): δ = 7.95-7.98 (m, 1 H, ArH), 8.18-8.21 (m, 1 H, ArH), 8.29-8.30 (m, 1 H, ArH), 10.84 (s, 2 H, NH).