Synthesis of some 2,4‐disubstituted tetrahydropyrimido[4,5‐b]quinolines as potential antitumor agents

Cyclocondensations of two 2,4‐disubstituted 6‐aminopyrimidines with 2‐chloro‐1‐cyclohexenecarboxaldehyde afforded in each case a new regiospecific synthesis of tricyclic, linear disubstituted 6,7,8,9‐tetrahydro‐pyrimido[4,5‐b]quinolines 2 and 3 in excellent yields. The linear structures and hence the regiospecificity of the synthesis were established using 1H nmr and 13C nmr. The growth of leukemia L1210 cells in culture was inhibited 50% by 2 at 30 × 10−6M and 48% by 3 at 100 × 10−6M.