Neue Wege in der Chemie der Pyridazone

Abstract

Abb. 1. Zur Hydrolyse von Cm-, Cis-, Cm-und CzyYliden (c = 2.75.10-2 Mol/I) im MethanoUWasser-Gemisch (4:5) hei a) 26'C und b) 4 "C. Ordinate: x = Molmenge verbrauchte BaseIMolmenge Phosphoniumsalz. Abszisse: Dauer der Hydrolyse t [minl.Zerfall der Phosphoniumsalze unter dem EinfluB von Alkoholaten beobachten. Erst bei Wasserzusatz trat eine Spaltung ein, bei der immer der als Anion stabilste Rest in unserem Fall das Trimethylcyclohexen-Derivatabgespalten wurde [ *]. Die Haftfestigkeit dieser Reste nimmt dabei infolge der Resonanzstabilisierung mit zunehmender Kettenlange ab. Die leichte Spaltbarkeit laBt sich praparativ verwerten. So entsteht zurn Beispiel aus dein Axerophthyl-triphenylphosphoniumsalz (10)

Reaction of chloropyridazin-3(2H)-ones with iodide. Part II.

“…Compound 6 was reported previously, 16 however, no experimental details or spectral data were given. Thus, it was of interest to prepare this compound by the reaction of Z-2,3-dichloro-4-oxo-4-phenylbutenoic acid 5 17 with hydrazine hydrate in boiling glacial acetic acid (Scheme 1).…”

“…4,5-Dichloro-6-phenylpyridazin-3(2H)-one (6). 16 A three-neck, round-bottom flask equipped with a reflux condenser, thermometer and dropping funnel was charged with Z-2,3-dichloro-4-oxo-4-phenylbutenoic acid 5 17 (193.0 mmol), and glacial acetic acid (90 mL). The funnel was charged with 99 % hydrazine monohydrate (24.0 mL, 500.0 mmol).…”

Application of Cross‐Coupling and Metalation Chemistry of 3(2H)‐Pyridazinones to Fungicide and Herbicide Discovery

“…(Scheme 4) Many substrates were prepared by traditional methods via reaction of mucobromic acid with various aryl or alkyl hydrazines followed by reaction with sodium methoxide. [7] Scheme 3…”

“…42 a number of commercial products such as Syngenta's trifloxystrobin (6), which contains an oxime containing pharmacophore and an acetophenone oxime containing side chain. (Figure 2) The successful modification of the natural methoxyacrylate pharmacophore inspired scientists at DuPont to investigate N-methyltriazolinones (7) as cyclic pharmacophores, which proved to be highly active fungicides. [3] In light of these last pharmacophores, replacing the triazolinone ring with an appropriately substituted pyridazinone became an appealing synthetic target.…”

Recyclization of 2-(3,6-diaryl-2,5-dihydropyridazin-4-yl)-1H-benzimidazoles to 2-[(3,5-diarylpyrazol-4-yl)methyl]-1H-benzimidazoles

“…This assists the electronic effect of both nitrogen atoms of the 4,5-dihydropyrazole ring (donor for one and acceptor for the other) and also simultaneously the aromatization of the pyrazole ring to give the final products 3a-g. The recyclization of certain pyridazine compounds to pyrazoles has been reported previously [7][8][9][10][11] but they differ from that given above by one overall feature which is a result of the opening of an existing and formation of a new nitrogen-carbon bond. We have not found any evidence for the restructuring of a pyridazine ring to a pyrazole via formation of a new and fission of an existing carbon-carbon bond.…”