39513-08-1

Upstream product

• 60-34-4 methylhydrazine 
• 10488-87-6 ethyl 2-benzoylpropionate 
• 87389-78-4 2-amino-4-methyl-5-phenyl-1,2-dihydro-pyrazol-3-one 
• 74-88-4 methyl iodide 
• 39513-01-4 1-amino-5-methoxy-4-methyl-3-phenylpyrazole 

Relevant academic research and scientific papers

N-Aminopyrroledione-hydrazonoketene-pyrazolium oxide-pyrazolone rearrangements and pyrazolone tautomerism

Flash vacuum thermolysis (FVT) of 1-(dimethylamino)pyrrole-2,3-diones 5 causes extrusion of CO with formation of transient hydrazonoketenes 7. The transient ketenes 7 are observable in the form of weak bands at 2130 (7a) or 2115 cm-1 (7b) in the Ar matrix IR spectra resulting from either FVT or photolysis of either 5 or 1,1-dimethylpyrazolium-5-oxides 8, and these absorptions are in excellent agreement with B3LYP/6-31G* frequency calculations. Under FVT conditions the ketenes 7 cyclize to pyrazolium oxides 8, which undergo 1,4-migration of a methyl group to yield 1,4-dimethyl-3-phenylpyrazole-5(4H)-one 9a and 1,4,4-trimethyl-3-phenylpyrazole-5(4H)-one 9b. All three tautomers of 9a have been characterized, viz. the CH form 9a (most stable form in the gas phase, the solid state and solvents of low polarity), the OH form 9a′ (metastable solid at room temperature) and the NH form 9a″ (stable in aprotic dipolar solvents). The isomeric 1,4-dimethyl-5-phenylpyrazole-3(2H)-one 12 tautomerizes to the 3-hydroxypyrazole 12′. The crystal structure of the hydrochloride 14 of 9a′/9a″ is reported, representing the first structurally characterised example of a protonated 5-hydroxypyrazole.

Mechanisms of Heterocycle Ring Formation. Part 5. A Carbon-13 Nuclear Magnetic Resonance Study of Pyrazolinone Synthesis by the Reaction of β-Ketoesters with Substituted Hydrazines

The 16 reactions between each of four hydrazines and four β-ketoesters have been followed by 13C n.m.r. spectroscopy.Peaks were assigned to starting materials, intermediates, and products, and reaction mechanisms determined and rationalized.Most rections proceed by attack of the least hindered hydrazine nitrogen atom on the keto carbon group of the ketoester.Relative rates of nucleophilic attack determine the build-up of intermediate and in some cases the nature of the products formed.

1-Aminopyrazolin-5-ones. Synthesis and reactivity

A synthesis of 1-aminopyrazolin-5-ones (I) by chloramine attack on the 2-benzylpyrazolones (IV d-e) has been accomplished.Nucleophilic substitution reactions of aminopyrazolones (I) are investigated; with 1,4-diketones, N,N'-pyrrolylpyrazolones (XVIIa-c)