Equivalent Atrop- and Positional Isomerism in Styrene Derivatives Prepared by Enantioselective 1,3-Diarylation

Area of Science:

• Organic Chemistry
• Catalysis
• Stereochemistry

Background:

• Isomerism describes molecules with identical atoms but distinct spatial arrangements and properties.
• Coexisting multiple forms of isomerism within a molecular pair is a rare phenomenon.
• Understanding and controlling isomerism is crucial for developing molecules with specific functions.

Purpose of the Study:

• To report a novel method for synthesizing substituted styrenes with coexisting atrop- and positional isomerism.
• To elucidate the mechanism underlying the formation of these unique isomeric structures.
• To explore the catalytic role of palladium and amino acids in this transformation.

Main Methods:

• Utilized a reaction system combining palladium and amino acid cocatalysts.
• Investigated the conversion of ortho-alkenyl benzaldehydes to substituted styrenes.
• Employed Density Functional Theory (DFT) calculations to analyze reaction pathways and stereoselectivity.

Main Results:

• Achieved the synthesis of substituted styrenes exhibiting both atrop- and positional isomerism from a single reaction.
• The reaction proceeds via successive Mizoroki-Heck arylation steps.
• DFT calculations revealed stereoselective beta-H elimination driving atroposelectivity and thermodynamic stability favoring Z-isomer formation.

Conclusions:

• A novel catalytic system efficiently generates molecules with coexisting atrop- and positional isomerism.
• The reaction mechanism involves stereoselective steps crucial for controlling isomer formation.
• This work expands the understanding of isomerism and provides a new synthetic route to complex molecules.