Synthesis of Bis-Benzo-12-Crown-4 Ethers

Abstract

Bis-crown ethers with benzo-15-crown-5 moieties have been known to form stable sandwiched type complexes with ion pairs of potassium salts in organic solvents.¹ The separation of ion pairs results in an increase of the anion reactivities in nucleophilic substitution reactions.² Recently, we have reported the synthesis of bis-crown ethers with either benzo-15-crown-5 or benzo-18-crown-6 moieties bridged only by ether functional group.³ When these bis-crown ethers are used as phase transfer reagents in phase transfer reactions, their catalytic effects depend on the type of crown moiety.⁴