Synthesis of New Lipophilic Sulfones and Their Use in Cyclization Reactions

Analytically pure novel dibenzylsulfanes 2a,b were synthesized by established reactions. Their oxidation by hydrogen peroxide resulted in the formation of the corresponding sulfones 3a,b , which were isolated in high yields. Analogously, the new bis-sulfone 7 was prepared starting from bis-bromo derivative 4 via bis-sulfane 6 . The sulfones obtained reacted readily with bis-imidoylchlorides 8 , yielding highly substituted dihydrothiophene-S,S-dioxides of type 9 and 10 . Due to their vicinal amino-imino substructures, these cyclic sulfones proved to be excellent chelating ligands, exemplified by the preparation of the palladium complex 11 .