Synthesis of Bicyclo[1.1.1]pentane Bioisosteres of Internal Alkynes and para‐Disubstituted Benzenes from [1.1.1]Propellane

We report a general preparation of arylated bicyclo1.1.1]pentanes through the opening of 1.1.1]propellane with various arylmagnesium halides. After transmetalation with ZnCl₂ and Negishi cross‐coupling with aryl and heteroaryl halides, bis‐arylated bicyclo1.1.1]pentanes are obtained. These bis‐arylated bicyclo1.1.1]pentanes may be considered as bioisosteres of internal alkynes. Bioisosteres of tazarotene and the metabotropic glutamate receptor 5 (mGluR5) antagonist 2‐methyl‐6‐(phenylethynyl)pyridine were prepared and their physicochemical properties were evaluated.