The cyclodimerization of diphenylacetylene derivatives catalyzed by a platinum-silylene complex is reported. The reaction proceeds via the cleavage of a carbon-hydrogen bond at the ortho-position of an alkynyl group and no additives are needed. Platinum complexes bearing other common ligands, such as phosphines and NHCs, failed to promote this reaction, highlighting the utility of the silylene ligand in this reaction.

Metronidazole is one of the first‐line treatments for non‐severe Clostridium difficile infections (CDI). However, resistance limits its use in cases of severe and complicated CDI. Structure–activity relationships previously described for the 5‐nitroimidazole series have shown that functionalization at the 2‐ and 4‐positions can impart better activity against parasites and anaerobic bacteria than metronidazole. Herein we report the synthesis of new 2,4‐disubstituted 5‐nitroimidazole compounds that show potent antibacterial activity against C. difficile. We used a vicarious nucleophilic substitution of hydrogen (VNS) reaction to introduce a phenylmethylsulfone at the 4‐position and a unimolecular radical nucleophilic substitution (SRN1) reaction to introduce an ethylenic function at the 2‐position of the 5‐nitroimidazole scaffold.