Synthesis of 7-benzyl-5-(piperidin-1-yl)-6,7,8,9-tetrahydro-3H-pyrazolo[3,4-c][2,7]naphthyridin-1-ylamine and its analogs as bombesin receptor subtype-3 agonists.

The original structure assignment of 2, a high-throughput screening hit obtained from an external vendor, was revised based on multiple NMR studies. A novel synthetic route was developed for 2 and multi-gram quantities were prepared for pharmacokinetic and efficacy studies. Its activity on the BRS-3 receptor was confirmed, and additional SAR was explored.