A New Method for the Synthesis of Imidazolidinone- and Benzimidazolone-containing [2.2]Cyclophanes

formula presented A novel acid-catalyzed double nucleophilic addition of bisthiols to heterocyclic bisacetals gives sulfur-containing macrocycles in good yield. Crossover experiments revealed that the acid-catalyzed N-acyl iminium cyclization for the imidazolidinones is reversible. The sulfur atom in the bridge was extruded photochemically, giving new [2.2]heterophanes containing the imidazolidinone and benzimidazolone ring systems. The determined crystal structures for representative members in the benzimidazolone series are also reported.