Synthesis of a 2,4,6-trisubstituted 5-cyano-pyrimidine library and evaluation of its immunosuppressive activity in a Mixed Lymphocyte Reaction assay.

A series of novel pyrimidine analogues were synthesized and evaluated for immunosuppressive activity in the Mixed Lymphocyte Reaction assay, which is well-known as the in vitro model for in vivo rejection after organ transplantation. Systematic variation of the substituents at positions 2, 4 and 6 of the pyrimidine scaffold led to the discovery of 2-benzylthio-5-cyano-6-(4-methoxyphenyl)-4-morpholinopyrimidine with an IC(50) value of 1.6 μM in the MLR assay.