Developing a Modern Approach To Account for Steric Effects in Hammett-Type Correlations

Area of Science:

• Organic Chemistry
• Catalysis
• Stereochemistry

Background:

• Understanding substituent effects is crucial for controlling chemical reactions.
• Predicting site and enantioselectivity in catalytic processes remains a challenge.

Purpose of the Study:

• To investigate the impact of aryl ring substitution on selectivity in three distinct catalytic reactions.
• To develop improved parameters for predicting substituent effects in organic synthesis.

Main Methods:

• Enantioselective palladium-catalyzed redox-relay Heck reaction.
• Palladium-catalyzed β-aryl elimination.
• Benzoylformate decarboxylase-catalyzed benzoin condensation.
• Analysis using Natural Bond Orbital (NBO) charges, IR carbonyl stretching frequency, and Sterimol values.

Main Results:

• Substituent effects on selectivity were successfully correlated with NBO charges, IR frequencies, and Sterimol values.
• These parameters provide a more comprehensive analysis than traditional Hammett values.
• The study demonstrates the utility of these parameters in predicting selectivity across different reaction types.

Conclusions:

• NBO charges, IR carbonyl stretching frequency, and Sterimol values are effective descriptors for substituent effects in catalytic reactions.
• These parameters offer a valuable tool for analyzing and predicting site and enantioselectivity.
• The findings advance the understanding of substituent influences in asymmetric catalysis and organic synthesis.