N-Heterocyclic carbenes derived from imidazo[1,5-a] pyridines related to natural products: synthesis, structure and potential biological activity of some corresponding gold(I) and silver(I) complexes

A series of Au(I) complexes (12-16) and Ag(I) complexes (17-20) derived from imidazo[1,5-a] pyridin-3-ylidenes were synthesized from AuCl(SMe2) or by reacting silver( I) acetate with 2,5-dimethylimidazo[1,5-a] pyridin-2-ium iodide or imidazo[ 1,5-a] pyridin-2-ium salts, and were characterized using NMR spectroscopy, mass spectrometry and elemental analyses. In addition, the Au(I) complex 13 and the Ag(I) complex 19 were characterized using single-crystal X-ray diffraction. Using paclitaxel as a standard, all Au(I) and Ag(I) N-heterocyclic carbene complexeswere evaluated for their in vitro anti-tumour activity against 12 cell lines using amonolayer cell survival and proliferation assay. The highest anticancer activity was found for complexes 15, 13 and 14 with mean IC50 values of 10.09, 10.42 and 12.28 mu M, respectively. Copyright (C) 2016 John Wiley & Sons, Ltd.