KDR inhibitor with the intramolecular non-bonded interaction: conformation-activity relationships of novel indole-3-carboxamide derivatives.

We previously reported that compound 1, having a similar conformation to PTK787 (2) by forming a pseudo ring structure with an intramolecular non-bonded S-O interaction, exhibited a potent inhibitory activity against VEGFR2 tyrosine kinase (KDR). Applying the ideas of pseudo ring formations, we have designed three types of novel indole carboxamide derivatives 5-7 with an intramolecular hydrogen bonding or non-bonded S-O interaction. We describe the design and synthesis of 5-7, and also discuss the relationships of their KDR inhibitory activity and conformations that were stabilized by their intramolecular non-bonded interactions.