Covalent Templated Catenane Synthesis Requiring Hindered Ester Cleavage

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Materials Science

Background:

• Previous work established methods for synthesizing hetero [n]rotaxanes using a 2,5-dihydroxyterephthalate scaffold.
• The synthesis of mechanically interlocked catenanes presents greater challenges than rotaxanes due to the need for efficient macrocycle closure.

Purpose of the Study:

• To develop an efficient strategy for synthesizing mechanically interlocked catenanes.
• To overcome challenges associated with macrocycle closure and subsequent cleavage of the linking unit.

Main Methods:

• Utilized a 2,6-dihydroxyterephthalate scaffold to preorganize components for efficient second macrocycle closure.
• Introduced 4-OMe groups onto the macrocyclic phenyl rings to facilitate cleavage.
• Employed aluminum hydride as a nucleophile to cleave the sterically hindered ester linkage.

Main Results:

• Demonstrated that proper preorganization with 2,6-dihydroxyterephthalate is crucial for efficient catenane formation.
• Showcased the successful cleavage of a sterically hindered terephthalate ester using aluminum hydride.
• Liberated the mechanically interlocked catenane architecture after overcoming oxidative cleavage limitations.

Conclusions:

• The study presents a robust method for constructing complex catenane architectures.
• The developed strategy overcomes significant synthetic hurdles in supramolecular chemistry.
• This work advances the synthesis of mechanically interlocked molecules.