Synthesis of ¹⁴ C- and ² H-labelled CHF6001: A new potent PDE4 inhibitor

An 8-step preparation of ¹⁴ C-labelled CHF6001, a potent phosphodiesterase 4 inhibitor in the treatment of respiratory diseases, is described. An overall yield of approximately 9% was obtained starting from copper[¹⁴ C]cyanide. The synthesis of a stable labelled version of CHF6001 is also reported using the commercially available trideuterated bromomethylcyclopropane as starting material.