Isolation, structure, synthesis and cytotoxicity of an unprecedented flupirtine dimer

摘要

A previously unknown dimer of the well-established analgesic flupirtine has been found, and its structure was revealed by ESI-MS, NMR spectroscopy and an independent synthesis. Thus, starting from 2-amino-6-chloro-3-nitro-pyridine the target compound was obtained in a four-step synthesis. Key-step of this synthesis is a nickel-mediated aryl-aryl coupling. The dimer 4 did not show any cytotoxicity, and its IC_(50) values were > 30 μm for all six human cancer cell lines and mouse fibroblasts used in this study.