Synthesis of Ethyl 2-[alkyl(benzyl)sulfanylmethyl]-3oxobutanoates and 3<i>H</i>-pyrazol-3-ones Based of Them
Three-component condensation of acetoacetic ester with formaldehyde and alkanethiols in the presence of 0.1 equiv of sodium hydroxide led to the formation of ethyl 2-[(alkylsulfanyl)methyl]-3-oxobutanoates, while thiometylation with phenylmethanethiol produced the ethyl 2-[(benzylsulfanyl)methyl]-2-(hydroxymethyl)-3oxobutanoate. The resulting compounds reacted with hydrazine hydrate in ethanol at room temperature to give 4[(alkylsulfanyl)methyl]- or 4-[(benzylsulfanyl)methyl]-5-methyl-2,4-dihydro-3 H -pyrazole-3-ones that existed mainly in the 1 H -pyrazole-5(3)-oles form in DMSO- d 6 solution.