A novel one-pot method for the preparation of pyrazoles by 1,3-dipolar cycloadditions of diazo compounds generated in situ

Journal of Organic Chemistry

Volumn 68, Issue 13, 2003, Pages 5381-5383

  Aggarwal, Varinder K ^a   De Vicente, Javier ^a   Bonnert, Roger V ^b  

^a UNIVERSITY OF BRISTOL   (United Kingdom)

^b ASTRAZENECA   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

ADDITION REACTIONS; ALDEHYDES; STEREOCHEMISTRY;

CYCLOADDITION;

AROMATIC COMPOUNDS;

ALDEHYDE; ALKYNE; DIAZO DERIVATIVE; IMIDAZOLE DERIVATIVE; N VINYLIMIDAZOLE; PYRAZOLE DERIVATIVE; UNCLASSIFIED DRUG;

1,3 DIPOLAR CYCLOADDITION; ARTICLE; CYCLOADDITION; STEREOCHEMISTRY; SYNTHESIS;

EID: 0037533016     PISSN: 00223263     EISSN: None     Source Type: Journal    
DOI: 10.1021/jo0268409     Document Type: Article

References (18)

1. Elguero, J. In Comprenhensive Heterocyclic Chemistry; Katritzky, A., Ed.; Pergamon Press: Oxford, 1984; Vol. 5, pp 277-282.
2. Elguero, J. In Comprenhensive Heterocyclic Chemistry II; Shinkai, I., Ed.; Elseiver: Oxford, 1996; Vol. 3, pp 3-75.
3. Kost, A. N.; Grandberg, I. I. Adv. Heterocycl. Chem. 1966, 6, 347-429.
4. Padwa, A. 1,3-Dipolar Cycloaddition Chemistry; John Wiley & Sons: New York, 1984; Vol. I.
5. Wiley, R. H.; E., H. P. Org. Synth. 1951, 31, 43-44.
6. Aryldiazomethanes have been prepared by vacuum pyrolysis of the hydrazone salt. See: Creary, X. Org. Synth. 1986, 64, 207. We have carried out the Creary preparation a large number of times over a 5-year period but on three occasions experienced minor explosions. We therefore sought methods for generating the diazo compound in situ to avoid the need to carry out the vacuum pyrolysis.
7. Aggarwal, V. K.; Alonso, E.; Hynd, G.; Lydon, K. M.; Palmer, M. J.; Porcelloni, M.; Studley, J. R. Angew. Chem., Int. Ed. 2001, 40, 1430-1433.
8. Aggarwal, V. K.; de Vicente, J.; Bonnert, R. V. Org. Lett. 2001, 3, 2785-2788.
9. Aggarwal, V. K.; de Vicente, J.; Pelotier, B.; Holmes, I. P.; Bonnert, R. V. Tetrahedron Lett. 2000, 52, 10327-10331.
10. 2, see: Mancera, M.; Rodriguez, E.; Roffe, I.; Galbis, J. A. Carbohydr. Res. 1994, 253, 307-316.
11. 2, see: Mancera, M.; Rodriguez, E.; Roffe, I.; Galbis, J. A. Carbohydr. Res. 1994, 253, 307-316.
12. 2, see: Mancera, M.; Rodriguez, E.; Roffe, I.; Galbis, J. A. Carbohydr. Res. 1994, 253, 307-316.
13. 2, see: Mancera, M.; Rodriguez, E.; Roffe, I.; Galbis, J. A. Carbohydr. Res. 1994, 253, 307-316.
14. 2, see: Mancera, M.; Rodriguez, E.; Roffe, I.; Galbis, J. A. Carbohydr. Res. 1994, 253, 307-316.
15. 2, see: Mancera, M.; Rodriguez, E.; Roffe, I.; Galbis, J. A. Carbohydr. Res. 1994, 253, 307-316.
16. Bastide, J.; Henri-Rousseau, O. Bull. Soc. Chim. Fr. 1973, 2294-2296. 1,3-Dipolar cycloadditions onto electron-rich acetylenes form the 3,4-regioisomer and cycloaddition onto electronically neutral acetylenes (alkyl substituted) give regioisomeric mixtures of pyrazoles. See ref 4.
17. 3-Substituted pyrazoles can also be prepared by cycloaddition of diazomethane with monosubstituted acetylenes. See: Kirmse, H. Justus Liebigs Ann. Chem. 1958, 614, 1.
18. The formation of side product 5 could be formed by reaction of the tosylhydrazone salt 1 with phenyldiazomethane in the presence of a protic source.