2-Arylacetic anhydrides as ammonium enolate precursors

Area of Science:

• Organic Chemistry
• Asymmetric Catalysis
• Synthetic Methodology

Background:

• Ammonium enolates are valuable intermediates in organic synthesis.
• Catalytic asymmetric reactions are crucial for producing enantiomerically pure compounds.
• Developing efficient methods for constructing complex molecules is a key challenge.

Purpose of the Study:

• To develop a catalytic asymmetric intermolecular Michael addition-lactonisation process.
• To utilize readily prepared 2-arylacetic anhydrides as ammonium enolate precursors.
• To achieve high yields and stereoselectivity in the synthesis of diverse building blocks.

Main Methods:

• Employing isothiourea (HBTM-2.1) as an organocatalyst.
• Utilizing 2-arylacetic anhydrides as starting materials.
• Performing catalytic asymmetric intermolecular Michael addition followed by lactonisation.

Main Results:

• The reaction proceeded with good to excellent yields.
• High diastereoselectivity (up to 98:2 dr) was achieved.
• Excellent enantioselectivity (up to >99% ee) was observed.
• Diverse synthetic building blocks were successfully synthesized.

Conclusions:

• Readily prepared 2-arylacetic anhydrides are effective precursors for catalytic asymmetric Michael addition-lactonisation.
• Isothiourea (HBTM-2.1) catalysis provides a powerful route to stereochemically rich compounds.
• This methodology offers a versatile approach for synthesizing valuable synthetic building blocks.