Ethyl 3-oxobutanoate, reaction with hydrazones

Diazotization of 4-[(4-aminophenyl)sulfonamido]-2,6-dimethyl pyrimidine 10, followed by coupling of the diazonium salt with ethyl 3-oxobutanoate 11a or l,3-diphenyl-l,3-propanedione lib, afforded hydrazones 12a,b. Reaction of hydrazone 12a with aminoguanidine nitrate in refluxing acetic acid yielded the pyrazol-3-one 13a in 55% yield (00JIC42) (Scheme 4). 

The reaction of ethyl 3-oxobutanoate with 4-aryltetrahydropyridazine-3,6-di(Mie 3-hydrazones 60a-d afforded the corresponding hydrazonobutanoates 61a-d. When heated with ethanolic sodium ethoxide, compounds 618-d cyclized to the sodium derivatives 62a-d which, upon acidification, gave the respective pyrazol-3-one derivatives 63a-d (97JHC389) (Scheme 19). 

In the reaction of arylhydrazides 73a, benzylhydrazide 73b, aryloxymethylhy-drazides 73c, or 1 -styrylhydrazide 73d with ethyl 3-oxobutanoate in boiling diox-ane, the corresponding hydrazones 86a-d were obtained in good yields. The latter... 

The Mannich reaction and its variants have been reviewed, mainly focussing on asymmetric catalysis thereof. Catalytic, enantioselective, vinylogous Mannich reactions have also been reviewed, covering both direct and silyl dienolate methods. Another review surveys Mannich-type reactions of nitrones, oximes, and hydrazones. A pyrrolidine-thiourea-tertiary amine catalyses asymmetric Mannich reaction of N-Boc-imines (e.g. Ph-Ch=N-Boc) with ethyl-4-chloro-3-oxobutanoate to give highly functionalized product (16). Addition of triethylamine leads to one-pot intramolecular cyclization to give an 0-ethyl tetronic acid derivative (17). ... 

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