Synthesis of amino acids from substituted cyanoacetic ester; 4-alkyl-3-aminopyrazolones

Four α-amino acids, namely, norleucine, isoleucine, methionine, and S-benzylhomocysteine, have been prepared from the corresponding alkylcyanoacetic esters. Methionine has been obtained in excellent yield.The intermediate alkylcyanoacethydrazides formed 4-alkyl-3-aminopyrazolones. Four members of this new series, 4-n-butyl-, 4-sec-butyl-, 4-(β-methylthiolethyl)-, and 4-(β-benzylthiolethyl)-3-aminopyrazolones are described and their ultraviolet absorption spectra given.The following compounds have also been isolated: ethyl α-cyano-γ-methylthiolbutyrate, ethyl α-cyano-γ-benzylthiolbutyrate, α-cyano-n-caprohydrazide, isopropylidene α-cyano-n-caprohydrazide, anisal α-cyano-β-methylvalerhydrazide, anisal α-cyano-γ-methylthiolbutyrhydrazide, and anisal α-cyano-γ-benzylthiolbutyrhydrazide.