Atroposelective Arene-Forming Wittig Reaction by Phosphorus P^III/P^V=O Redox Catalysis

Area of Science:

• Organic Chemistry
• Catalysis
• Asymmetric Synthesis

Background:

• The Wittig reaction is a versatile method for alkene synthesis from aldehydes and ketones.
• Recent advances include chiral phosphine catalysis for stereoselective transformations.
• Developing enantioselective methods for complex molecule synthesis remains a key challenge.

Purpose of the Study:

• To develop a stereocontrolled Wittig reaction for the enantioselective synthesis of biaryl atropisomers.
• To establish a mild catalytic system using phosphine redox catalysis.
• To explore the scope and efficiency of this new synthetic strategy.

Main Methods:

• Employing chiral phosphine catalysis under P(III)/P(V)=O redox cycling.
• Utilizing tert-butyloxycarbonylated Morita-Baylis-Hillman adducts to trigger endogenous base release.
• Performing a stereocontrolled, arene-forming Wittig reaction.

Main Results:

• Demonstrated phosphine redox catalysis for atroposelective Wittig reactions.
• Achieved the synthesis of diverse biaryl atropisomers with high enantioselectivity (up to 94:6).
• The key step involves catalyst intramolecularization triggering base release for mild reaction conditions.

Conclusions:

• Phosphine redox catalysis provides an effective route to enantiomerically enriched biaryl atropisomers.
• The developed method offers a mild and versatile approach to synthesizing valuable chiral compounds.
• This strategy expands the utility of the Wittig reaction in asymmetric synthesis.