Paal-Knorr Pyrrole Synthesis

C. Paal, Ber. 18, 367 (1885); L. Knorr, ibid. 299.

Formation of pyrroles via cyclization of 1,4-dicarbonyl compounds with ammonia or primary amines:

H. Fischer, H. Orth, Die Chemie des Pyrrols 1 (Leipzig, 1934) p 34; D. M. Young, C. F. H. Allen, Org. Syn. 16, 25 (1936); A. H. Corwin, Heterocyclic Compounds 1, 290 (1950); N. P. Buu-Hoi et al., J. Org. Chem. 20, 639, 850 (1955); H. H. Wassermann et al., Tetrahedron 32, 1863 (1976). Mechanistic studies: V. Amarnath et al., J. Org. Chem. 56, 6924 (1991); idem, K. Amarnath, ibid. 60, 301 (1995). Applications: S.-X. Yu, P. W. Le Quesne, Tetrahedron Letters 36, 6205 (1995); R. Ballini et al., Synlett 3, 391 (2000). Review: S. E. Korostova et al., Russ. J. Org. Chem. 34, 1691 (1998). Cf. Hantzsch Pyrrole Synthesis; Knorr Pyrrole Synthesis.