Reaktionen substituierter Cumarine, Furocumarine und Khellinon‐styryl‐Derivate mit Hydrazin und Phenylhydrazin

Abstract

Die Pyrazolonderivate 5a-c entstehen aus 4-substituierten Cumarinen rnit Hydrazinhydrat, 4-Hydroxy-cumarine rnit einem reaktionsfahigen Substituenten in 3-Stellung, z. B. 7a, b, reagieren mit Hydrazinhydrat ohne Offnung des Heteroringes zu Sa, b bzw. 9a, b. Die Furocumarine 3a, b geben rnit Phenylhydrazin substituierte Pyrazolonderivate 10a, b oder deren Isomere. Analoge Verbindungen erhalt man auch aus 3c, d rnit Phenylhydrazin.Aus 3e, f entstehen entsprechend lOc, d. Das Nitroderivat 7c reagiert rnit Phenylhydrazin unter Eliminierung der Nitrogruppe zu 13. Die Pyrazoline 15a-i (oder deren Isomere) bilden sich aus 14a-f mit Phenylhydrazin; mit Hydrazinhydrat konnteti die entsprechenden Hydrazone isoliert werden.Cumarine verhalten sich unterschiedlich gegen Hydrazinhydrat. Einerseits reagieren Cumarinl) und Xanthotoxin 2 ) unter Offnung des Heteroringes zu P-Hydrazino-P-o-hydroxyphenyl-propionsaurehydrazid (1) bzw. 3-[5-(6-Hydroxy-7-methoxy-benzofuryl)]-acry~saurehydrazid (Z), Cumarin3), 3-Phenyl-3), 3-Carbathoxy-4) und 3-AcetyI-cumarin5) zum anderen

Efficient and Convenient Method for Synthesis of Benzofuran-3-acetic Acids and Naphthafuran-acetic Acids

“…agonist. [10][11][12][13] BENZOFURAN-3-ACETIC AND NAPHTHAFURAN-ACETIC ACIDS 3 In the IR spectrum of the prototype, compound 5a exhibited absorption band of carbonyl group at 1722 cm À1 and hydroxyl group at 3439 cm À1 . The 1 H NMR displayed two singlets at d 2.39 and 3.65 for methyl and methylene protons, respectively.…”

“…[27] Subsequent reaction of these substituted-4-bromomethylcoumarins 4 and 1 M sodium hydroxide was carried out at reflux, for 1-2 h, resulted in the formation of benzofuran-and naphthofuran-acetic acids 5a-p. The structures of the compounds were substantiated by infrared (IR), 1 H NMR, 13 C NMR, mass spectrometry (MS), and CHN analysis. The purity of these compounds was ascertained by thin-layer chromatography (TLC) and spectral analysis (Supplementary Data).…”

“…2). [10][11][12] It is well known that certain coumarin derivatives are transformed to other heterocycles such as pyrazoles [13] and pyrimidines [14] by their reaction with hydrazine hydrate and acetamidine or benzimidine, involving the cleavage of the lactone, respectively. The reaction of 4-formyl coumarins with phenyl hydrazine resulted in pyridazines.…”

5-Phenylpyridazinones-A serendipitous route from coumarins

“…Hydrazine hydrate and other double nucleophiles like amidines and thiourea are known to bring about similar ring opening of coumarins which have resulted in the formation of o-hydroxyphenyl substituted pyrazoles 22 and pyrimidines. 23 Further, an intramolecular nucleophilic attack of the hydrazine on the carbonyl group of the hydrazide followed by the expulsion of hydrazine results in the intermediates 5 which undergo in situ dehydrogenation to give pyridazinones 2.…”