Asymmetric bromolactonization using amino-thiocarbamate catalyst

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Bromolactonization is a valuable transformation for synthesizing lactones.
• Enantioselective synthesis of chiral lactones remains a significant challenge in organic chemistry.

Purpose of the Study:

• To develop a novel catalytic system for the enantioselective bromolactonization of unsaturated carboxylic acids.
• To demonstrate the broad applicability of the developed method in synthesizing valuable lactone intermediates.

Main Methods:

• Utilized a novel amino-thiocarbamate catalyst for bromolactonization.
• Investigated the reaction scope with various unsaturated carboxylic acids.
• Applied the protocol to the synthesis of key intermediates for VLA-4 antagonists.

Main Results:

• Successfully developed an amino-thiocarbamate-catalyzed bromolactonization.
• Achieved high yields (up to 99%) and excellent enantioselectivities (up to 93% ee) for 22 examples of γ-lactones.
• Demonstrated the utility of the method in synthesizing intermediates for VLA-4 antagonists.

Conclusions:

• The novel catalytic system provides an efficient and enantioselective route to γ-lactones.
• The methodology is applicable to the synthesis of complex molecules, including pharmaceutical intermediates.