1-Methyl-3-nitro-5-methoxycarbonyl Pyrazole

Pier Giovanni Baraldi*, Barbara Cacciari, Romeo Romagnoli and Giampiero Spalluto

Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17-19, I-44100 Ferrara, Italy.
Tel. 0039-(0)532-291293, Fax 0039-(0)532-291296 ([email protected] or [email protected])

Received: 3 February 1998 / Published: 18 February 1998

The nitroester 2 was prepared by the addition of meta-chloro-perbenzoic acid (m-CPBA) to 1 [1] according to the reported procedure [2,3].

To a stirred solution of 1 (524 mg, 3.67 mmol) in dry CHCl₃ (9 ml), heated at 70 °C, m-CPBA (3.18 g, 14.8 mmol, 4 eq) dissolved in dry CHCl₃ (23 ml), was added. After 1 h, TLC analysis (AcOEt, R_f 0.5), showed the disappearance of the starting material. The mixture was cooled and filtered through a pad of celite. The filtrate, was washed twice with aqueous 10% NaOH and the organic phase was dried (MgSO₄) and concentrated at reduced pressure. The residue was purified by crystallization (light petroleum/ether) to afford 2 as a white solid (476 mg,75%).

M.p. 66-68 °C.

TLC (AcOEt/light petroleum 7:3) R_f 0.37.

IR (KBr, cm^-1): 1730, 1550, 1380, 1330, 1300, 1270, 1130, 1090, 1000, 840, 760, 750.

¹HNMR (CDCl₃) d: 7.40 (s, 1H, CH); 4.29 (s, 3H, CO₂CH₃); 3.96 (s, 3H, N-CH₃).

Anal. calc. for C₆H₇N₃O₄ (185.14): C 38.93, H 3.81, N 22.70; found: C 38.71, H 3.89, N 22.89.

Acknowledgment: We gratefully acknowledge the Ministero Pubblica Istruzione (Grant 40% and 60%) for their generous support.

References

1. Lee, H. H.; Boyd, M.; Gravatt, G. L.; Denny, W. A. Pyrazole analogues of the bispyrrolecarboxamide anti-tumour antibiotics: synthesis, DNA binding and anti-tumour properties. Anti-Cancer Drug Res. 1991, 6, 501.

2. Emmons, W. D. The oxidation of amines with peracetic acid. J. Am. Chem. Soc. 1957, 79, 5528.

3. Gilbert K. E.; Borden, W. T. Peracid oxidation of aliphatic amines: general synthesis of nitroalkanes. J. Org. Chem. 1979, 44, 659.

Sample availability: Available from the authors.

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