2.3- Dimethyl- l-phenylpyrazol-5-one

A number of complexes with ligands related to amides, lactams and antipyrine (2,3-dimethyl-l-phenylpyrazol-5-one), as well as complexes with dicarboxylic acid amides are also known (Table 36), but little structural information is available for them. The diantipyrylmethane complex, UI4-4L-2H20, is probably ionic, [UL4]I4-2H20. 

Table 36 Complexes of Actinide(IV) Compounds with Lactams, Antipyrine (2,3-Dimethyl-l-phenylpyrazol-5-one, ATP) and its Derivatives, and Dicarboxylic Acid Amides...

Synthesis of (53) and (54) proceeds with ease on mixing the relevant reagents (Expts 8.14 and 8.15). /V-Methylation of (54) with dimethyl sulphate in the presence of alkali gives 2,3-dimethyl-l-phenylpyrazol-5-one (antipyrin), which was one of the earliest synthetic antipyretics. 

The parent compound (1) was discovered in 1891 by Tauber, who called it diphenyleneazone, and later phenazone. Unfortunately, the latter name was at one time also used for 2,3-dimethyl-l-phenylpyrazol-5-one (anti-pyrine). More recently 1 has been called 3,4-benzocinnoline and now benzo-[c]cinnoline, using Chemical Abstracts nomenclature. The numbering shown is that currently used Beilstein s Handbuch employed numbering analogous to that used for phenanthrene. 

If 2-hydroxyacetophenone analogues such as 3-acetyl-4,6-dimethyl-2-pyridone and 4-acetyl-5-hydroxy-3-methyl-l-phenylpyrazole are used as the methylene component in the condensation with R COaEt in the presence of LiH in THE or dioxane, the reaction gives the corresponding R -containing p-diketones 132 and 134, whose dehydration under the action of concentrated H2SO4 affords 8-aza-2-(polyfluoroaIkyl) chromones 133 [58] and 6-(polyfluoroalkyl)-3-methyl-l-phenylpyrano[2,3-c] pyrazol-4(17/)-ones 135 [59] (Scheme 41). 

Abarbi et al. (OOJOC4618) reacted 3-bromopropene and 2-bromomethylacrylic acid ethyl ester with the Grignard reagent derived from 1,5-dimethyl-3//-5-iodo-2-phenylpyrazol-3-one and diisopropyl magnesium, and obtained the corresponding 4-allyl-1,5-dimethyl-2-phenyl-1,2-dihydropyrazol-3-one and 2-(l, 5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-17/-pyrazol-4-ylmethyl)acrylic acid ethyl ester, respectively. 

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