Mechanically Planar Chiral Molecules by a SuFEx-Auxiliary Approach

Area of Science:

• Stereochemistry
• Supramolecular Chemistry
• Organic Synthesis

Background:

• Mechanical chirality in mechanically interlocked molecules (MIMs) offers unique properties but faces synthetic hurdles.
• Producing enantiopure mechanically planar chiral (MPC) molecules, especially at scale, remains a significant challenge.

Purpose of the Study:

• To develop a scalable, metal-free synthetic route for enantiopure mechanically planar chiral (MPC) molecules.
• To leverage the sulfur(VI) fluoride exchange (SuFEx) click reaction for the synthesis of MPC rotaxanes and catenanes.

Main Methods:

• Employing the SuFEx click reaction as an active template for synthesizing MPC rotaxanes.
• Utilizing a one-step auxiliary elimination (removal or oxidation of sulfinyl group) to achieve high enantiopurity (ee >99%).
• Developing derivative synthesis strategies for diverse functionalization of rotaxanes and subsequent transformation into catenanes.

Main Results:

• Successful gram-scale synthesis of MPC rotaxanes using a metal-free SuFEx approach.
• Efficient generation of enantiopure MPC rotaxanes and higher-order structures with high enantiomeric excess.
• Demonstrated conversion of enantiopure MPC rotaxanes into enantiopure MPC catenanes, preserving chirality.

Conclusions:

• The SuFEx click reaction provides a robust and scalable method for accessing enantiopure mechanically planar chiral molecules.
• This strategy significantly advances the synthesis of complex chiral mechanically interlocked molecules, including rotaxanes and catenanes.
• The developed methodology opens new avenues for exploring the applications of chiral MIMs.