Three-component asymmetric catalytic Ugi reaction--concinnity from diversity by substrate-mediated catalyst assembly

Area of Science:

• Organic Chemistry
• Catalysis
• Asymmetric Synthesis

Background:

• The Ugi reaction is a multicomponent reaction widely used in medicinal chemistry.
• Developing chiral catalysts for Ugi reactions is crucial for asymmetric synthesis.
• Previous efforts have not identified effective chiral catalysts for the three-component Ugi reaction.

Purpose of the Study:

• To identify the first chiral catalyst for the three-component Ugi reaction.
• To develop an efficient catalytic system for the asymmetric synthesis of alpha-amino amides.

Main Methods:

• Screening of a large set of BOROX catalysts.
• In situ assembly of BOROX catalysts from chiral biaryl ligands, amines, BH3·SMe2, and alcohols/phenols.
• Testing catalyst performance in the three-component Ugi reaction using aldehydes, secondary amines, and isonitriles.

Main Results:

• Identification of BOROX catalysts as effective chiral catalysts for the Ugi reaction.
• The optimal catalyst system (LAP 8-5-47) achieved excellent asymmetric induction.
• Successful synthesis of alpha-amino amides from various starting materials.

Conclusions:

• The first chiral catalyst for the three-component Ugi reaction has been identified.
• BOROX catalysts offer a promising route for asymmetric synthesis via the Ugi reaction.
• The catalytically active species is proposed to be a chiral boroxinate anion-iminium cation ion pair.