ISSN:
0021-8383
Schlagwort(e):
Chemistry
;
Organic Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The Reaction of α,β-Dihalogeno-propionitriles with Monosubstituted Hydrazines - A Simple Synthesis of 1-Substituted 3- or 5-Amino-pyrazolesIn methanol hydrazines 3, and α,β-dihalogeno-propionitriles 1, 2 even at 0°C irreversibly yield 3 · HX, and α-halogenoacrylonitriles 4, 5 (A1). Fast addition of alkyl- and aralkyl- hydrazines 3 to 4, 5 (C) gives 1-substituted 1-(2′-halogeno-2′-cyan-ethyl)-hydrazines 6, the addition of arylhydrazines 3 to 4, 5 (D) 1-aryl-2-(2′-halogeno-2′-cyan-ethyl)-hydrazines 8. In methanol 6 spontaneously cyclise (E) to hydrogen halides 7 · HX of 1-alkyl- and 1-aralkyl-3-amino-pyrazoles, 8 with 2 moles of acids (F) to salts 10 · 2HY of 1-aryl-4-halogeno-5-imino-pyrazolidines, and the free 10 spontaneously (G) to hydrogen halides 9 · HX of 1-aryl-5-amino-pyrazoles. Mechanisms (A1), (C), (D), (E), (F), and (G) are proved by t.l.c., 1H-n.m.r., and isolation of intermediates, the structures of 7 resp. 9, using the significant 1H-n.m.r.-parameter ΔHMPTCDCl3. Simple general syntheses are described for 3-amino-pyrazoles 7 (R = H, alkyl, aralkyl) or 5-amino-pyrazoles 9 (R = aryl) starting with α,β-dihalogeno-propionitriles 1, 2, and for α-bromo-acrylonitrile 5.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/prac.19793210112
