Acetoacetic esters reaction with hydrazines

C HgNjOjS. Colourless needles, with iH20. Prepared by reducing diazotized sulphanilic acid with an excess of sodium sulphite. It is a typical hydrazine in its reactions with ketones, and with acetoacetic ester. The latter reaction gives rise to the tartrazine dyestuffs, and is much used commercially. 

Solid-phase synthesis of substituted pyrazolones 550 from polymer-bound /3-keto esters 549 has been described (Scheme 68) <2001EJ01631>. Trisubstituted pyrazole carboxylic acids were prepared by reaction of polymer-bound arylidene- or alkylidene-/3-oxo esters with phenylhydrazines <1999S1961>. 2-(Pyrazol-l-yl)pyrimi-dine derivatives were prepared by cyclocondensation of ethyl acetoacetate and (6-methyl-4-oxo-3,4-dihydropyrimi-din-2-yl)hydrazine with aromatic aldehydes <2004RJC423>. Reactions of acylated diethyl malonates with hydrazine monohydrochloride in ethanol afforded 3,4-disubstituted-pyrazolin-5-ones <2002T3639>. Reactions of hydrazines with A -acetoacetyl derivatives of (45 )-4-benzyloxazolidin-2-one (Evans oxazolidinone) and (2R)-bornane-10,2-sultam (Oppolzer sultam) in very acidic media gave pyrazoles retaining the 3(5)-chiral moiety <1999S157>. 

Summary Mono(silyl)hydrazines condense to bis(silyl)hydrazines at higher temperature. The degree of oligomerization of mono- and dilithiated silylhydrazines in the crystal depends on the bulkiness of the substituents. Reactions of lithiated silylhydrazines with fluorosilanes lead, for example, to the formation of tetrakis(silyl)-hydrazines, six-, four- and five-membered rings. Formaldehyde derivatives of mono-(silyl)hydrazones are obtained in a reaction of mono(silyl)hydrazines with aqueous formaldehyde solution. 0-Silylpyrazolones can be synthesized by treating mono(silyl)-hydrazines with acetoacetic ester. A dipyrazolonesilane is formed in the reaction of an O-silylpyrazolone with dichlorodimethylsilane. 

In this reaction, the phenylhydrazone of ethyl acetoacetate was isolated as an intermediate and converted into the product. Further intermediates were detected by means of C-NMR spectroscopy [137]. Acetylenecarboxylic esters also react with hydrazines to give pyrazolones. 

The formation of pyridazines from three components was reviewed in CHEC-I and the most common examples are of reaction of an a-diketo compound, a hydrazine, and an ester or nitrile containing an adjacent activated methylene group, to give compounds like 4-cyano-3(2//)-pyr-idazinone or 3-amino-4-cyanopyridazines. A different type of example is illustrated by the condensation of a nitrostyrene with two equivalents each of methyl acetoacetate and hydrazine hydrate (Equation (36)) to give the pyridazine (126) in good yield <87JHC23>. 

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