Synthesis and Src kinase inhibitory activity of 2-phenyl- and 2-thienyl-7-phenylaminothieno[3,2-b]pyridine-6-carbonitriles

2-Phenyl-7-phenylaminothieno[3,2-b]pyridine-6-carbonitriles were recently reported to be inhibitors of Src kinase activity. In this study we present structure-activity relationships for additional thieno[3,2-b]pyridine-6-carbonitriles, modifying the substituents on the C-2 phenyl and C-7 phenylamino groups. Derivatives with various aminomethyl and aminoethyl substituents on the para position of the C-2 phenyl group retained the activity of the initial analogues. However, direct attachment of an amino group led to decreased activity. A 2,4-dichloro-5-methoxyphenylamino group at C-7 provided superior inhibition of Src enzymatic activity. Replacement of the C-2 phenyl group with a 3,5-substituted thiophene led to improved Src inhibitory activity compared to the parent compound, but other thiophene isomers were less active. One of the analogues reported here exhibited in vivo activity comparable to that of SKI-606, a related 3-quinolinecarbonitrile currently in clinical trials.