Synthesis of pyrimidine derivatives of amino acids using pig liver esterase and pancreas lipase.

The parent methyl ester of the N-1 substituted 5-chloropyrimidinone is hydrolysed by pig liver esterase to the corresponding carboxylic acid. The acid chloride was made with PCl5 in toluene, and coupling with benzyl and methyl esters of selected L-amino acids to the corresponding amides was done in dichloromethane in the presence of triethylamine. The benzyl and methyl ester protecting groups were hydrolysed with pancreas lipase or esterase in a pH-stat to yield the corresponding carboxylic acids.