Facile synthesis of<i>N</i>-α-boc-1,2-dialkyl-l-histidines: Utility in the synthesis of thyrotropin-releasing hormone (trh) analogs and evaluation of the cns activity
starting from N-α-trifluoroacetyl-L-histidine methyl ester is reported. The key steps involve direct and regiospecificN-1(τ) ring-alkylation of the N-α-trifluoroacetyl-L-histidine-methyl ester by suitable alkyl iodide in the presence of NaH in DMF at −15 °C followed by homolytic free radical C-2 alkylation via a silver catalyzed oxidative decarboxylation of alkylcarboxylic acid in the presence of ammonium