Aminomethylation of Symmetric Dialkylthioureas with Formaldehyde and Amino Acids

Condensation of 1,3-dialkylthiourea, formaldehyde, and terminal amino acids (C2, C3, or C4) taken in the 1 : 2 : 1 molar ratio has afforded the terminally substituted (3,5-dialkyl-4-thioxo-1,3,5-triazinan-1-yl)carboxylic acids.