Synthesis of Ethyl 2-[Alkyl(benzyl)sulfanylmethyl]-3-oxobutanoates and 3H-Pyrazol-3-ones Based Thereon

Three-component condensation of ethyl acetoacetate with formaldehyde and alkanethiols in the presence of 0.1 equiv of sodium hydroxide afforded ethyl 2-[(alkylsulfanyl)methyl]-3-oxobutanoates, and analogous reaction with phenylmethanethiol led to the formation of ethyl 2-[(benzylsulfanyl)methyl]-2-(hydroxymethyl)-3-oxobutanoate. The condensation products reacted with hydrazine hydrate in ethanol at room temperature to give 4-{[alkyl(or benzyl)sulfanyl]methyl}-5-methyl-2,4-dihydro-3H-pyrazol-3-ones which were shown to exist in DMSO-d6 mainly as 1H-pyrazol-5(3)-ol tautomers.