74
P. G. Baraldi et al.
SHORT PAPER
compound 9 was obtained as a red solid. Yield: 1.8 g (73%); mp:
102 °C.
IR (KBr): n = 3360, 1647, 1531, 1474, 1352, 1290, 1080, 718 cm-1.
1H NMR (CDCl3): d = 2.78 (s, 3H), 7.68 (t, 1H, J = 7.8 Hz), 7.76 (t,
1H, J = 8 Hz), 7.92 (d, 1H, J = 8.2 Hz), 8.37 (d, 1H, J = 8.2 Hz),
8.50 (br s, 2H).
b) Bradshaw, C. G.; Ceszkowski, K.; Turcatti, G.; Beresford,
I. J. M.; Chollet, A. J. Med. Chem. 1994, 37, 1991.
c) Lampe, D.; Potter, B. V. L. J. Chem. Soc., Chem. Comm.
1990, 1500.
(5) a) Mihailovic, M. L.; Cekovic, Z. In Encyclopedia of Reagents
for Organic Synthesis, Vol. 5; Paquette, L. A., Ed.; Wiley:
Chichester, 1995; p. 2949.
b) Butler, R. N. In Synthetic Reagents, Vol. 3; Pizey J. S., Ed.;
Wiley: New York, 1977, p. 277.
c) Butler, R. N.; Scott, F. L.; O'Mahony, T. A. F. Chem. Rev.
1973, 73, 93.
d) For a recent publication related to the oxidation by lead
tetraacetate see: Paredes, M. D.; Alonso, R. Tetrahedron Lett..
1999, 40, 3973.
5-Methyl-2-(3-nitro-phenyl)-4-nitroso-2H-pyrazol-3-ylamine
(10)
5-Methyl-2-(3-nitro-phenyl)-2H-pyrazol-3-ylamine 313 (2.18 g., 10
mmol) dissolved in EtOH (20 mL) was used. After the workup,
compound 10 was obtained as a red solid. Yield: 1.7 g (69%), mp:
135 °C.
(6) Taylor, E. C.; Beardsley, G. P.; Maki, Y. J. Org. Chem. 1971,
36, 3211.
(7) Taylor, E. C.; Maki, Y.; McKillop, A. J. Org. Chem. 1972, 37,
1601.
IR (KBr): n = 3358, 1642, 1531, 1476, 1350, 1238, 1070, 988, 739
cm-1.
1H NMR (CDCl3): d = 2.77 (s, 3H), 7.72 (t, 1H, J = 8 Hz), 7.92 (d,
1H, J = 8 Hz), 8.22 (d, 1H, J = 8.4 Hz), 8.38 (s, 1H), 8.50 (br s, 2H).
(8) Mohr, E. J. Prakt. Chem. 1909, 79, 45.
(9) Bertelson, R. C.; Glanz, K. D.; McQuain, D. B. J. Heterocycl.
Chem. 1969, 6, 317.
Pyrazolo[3,4-c]-1,2,5-oxadiazoles (15-21); General Procedure
The appropriate nitroso-amine pyrazole 8-14 (10 mmol) was dis-
solved in glacial HOAc (10 mL) at r.t.. Then, an equimolar amount
of Pb(OAc)4•3H2O (3.89 g., 10 mmol) was added in small portions
over 10 min and the disappearance of the starting material was ob-
served by TLC over 2 h. The solution was slowly diluted with H2O
(5 mL) and the resulting mixture, containing a yellow solid, was
cooled on ice-bath and the solid filtered off. The solid, washed with
H2O (20 mL), vacuum dried, and recrystallized from EtOH (15
mL), furnished 15-21 with excellent yields (88-97%).
(10) a) For the synthesis of the compound 11 see: Guarneri, M.;
Ferroni, R.; Fiorini, F. Gazz. Chim. Ital. 1968, 98, 569.
b) For the synthesis of the compound 12 see: Giori, P.;
Mazzotta, D.; Vertuani, G.; Guarneri, M.; Pancaldi, D.;
Brunelli, A. Il Farmaco Ed. Sci. 1981, 36, 1019.
c) For the synthesis of compounds 13 and 14 see: Ferroni, R.;
Milani, L.; Simoni, D.; Orlandini, P.; Poli. T.; Guarneri, M.;
Taddeo, U. Il Farmaco Ed. Sci. 1988, 43, 891.
(11) Baraldi, P. G.; Simoni, D.; Periotto, V.; Manfredini, S.;
Guarneri, M. Synthesis 1984, 148.
References
(12) Falzoni, S.; Munerati, M.; Ferrari, D.; Spisani, S.; Moretti, S.;
Di Virgilio, F. J. Clin. Invest. 1995, 95, 1207
(13) Alberti, C.; Tironi, C. Il Farmaco Ed. Sc. 1967, 22, 418.
(1) New address: Departamento de Quìmica Orgànica y
Farmacéutica, Facultad de Farmacia, Campus de Cartuja s/n,
18071 Granada, Spain.
(2) Wolff, K. Liebigs Ann. Chem. 1890, 79, 260.
(3) Paton, R. M. In Comprehensive Heterocyclic Chemistry, Vol.
6; Potts, K. T., Ed.; Pergamon: New York; 1984, p 393.
(4) a) Kobayashi, R.; Nakashima, K.; Sugano, K.; Nishikawa, M.;
Akiyama, S. Chem. Pharm. Bull. 1992, 40, 1327.
Article Identifier:
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Synthesis 2000, No. 1, 72–74 ISSN 0039-7881 © Thieme Stuttgart · New York