Planar chiral arene ruthenium complexes derived from R-carvone

Area of Science:

• Organometallic Chemistry
• Asymmetric Catalysis
• Synthetic Organic Chemistry

Background:

• Chiral ligands and catalysts are crucial for stereoselective synthesis.
• Ruthenium complexes are widely used in catalysis, including C-H activation.
• Developing novel chiral arene ruthenium complexes can expand catalytic applications.

Purpose of the Study:

• To synthesize novel planar-chiral arene ruthenium complexes.
• To investigate the catalytic activity of these complexes in C-H activation and related reactions.
• To evaluate the stereoselectivity of reactions mediated by the new chiral ruthenium catalysts.

Main Methods:

• Conversion of natural R-carvone into chiral 1-aryl-2-methyl-5-isopropyl-cyclohexadienes via cross-coupling reactions.
• Reaction of the synthesized dienes with RuCl3 to form planar-chiral ruthenium complexes [(arene)RuCl2]2.
• Testing the catalytic performance of the complex [(1-Ph-2-Me-5-iPr-C6H3)RuCl2]2 in C-H activation and intramolecular diazo compound insertion.

Main Results:

• Chiral cyclohexadienes were successfully synthesized and reacted with RuCl3 to yield planar-chiral ruthenium complexes in 70-75% yields.
• The synthesized chiral analogue [(1-Ph-2-Me-5-iPr-C6H3)RuCl2]2, similar to [(cymene)RuCl2]2, demonstrated activity in promoting C-H activation and intramolecular C-H insertion.
• The catalytic reactions mediated by the new complex resulted in products with low stereoselectivity.

Conclusions:

• Novel planar-chiral arene ruthenium complexes can be efficiently synthesized from natural R-carvone.
• These complexes exhibit catalytic activity in key organic transformations like C-H activation.
• Further development is needed to enhance the stereoselectivity of these chiral ruthenium catalysts.