Stereoselective On‐Surface Cyclodehydrofluorization of a Tetraphenylporphyrin and Homochiral Self‐Assembly

The thermally induced cyclodehydrofluorization of iron tetrakis(pentafluorophenyl)porphyrin proceeded highly stereoselectively to give a prochiral product on a gold surface in an ultrahigh vacuum, whereas dehydrocyclization of the respective iron tetrakisphenylporphyrin did not show such selectivity. Stereoselectivity was predominantly observed for closely packed layers, which is an indication of intermolecular cooperativity and steric constraints induced by adjacent species. Density functional theory identified intermolecular packing constraints as the origin of such selectivity during the reaction. Scanning tunneling microscopy revealed the formation of an enantiomerically pure two‐dimensional self‐assembly as a conglomerate of mirror domains. On‐surface two‐dimensional topochemistry, as reported herein, may open new routes for stereoselective synthesis. Thermally induced cyclodehydrofluorization of a tetraphenylporphyrin proceeded with high stereoselectivity on a gold surface in an ultrahigh vacuum to give the prochiral windmill product (see scheme), which aggregated into a two‐dimensional conglomerate. Such surface topochemistry enabled by alignment and dense packing may offer new possibilities for stereoselective synthesis in other systems.