Cascade Cyclizations of α,β-Unsaturated Thioesters: Additional Examples.

Area of Science:

• Organic Chemistry
• Catalysis
• Reaction Mechanisms

Background:

• Cascade cyclizations offer efficient synthetic routes.
• Thioesters are versatile synthetic intermediates.
• Understanding reaction mechanisms is crucial for catalyst design.

Purpose of the Study:

• To report additional examples of cascade cyclizations of alpha, beta-unsaturated thioesters.
• To elucidate the distinct mechanistic pathways involved.
• To highlight the role of amidine-based catalysts (ABCs) and thiolate nucleophiles.

Main Methods:

• Exploration of cascade cyclization reactions.
• Mechanistic studies to differentiate reaction pathways.
• Use of amidine-based catalysts (ABCs).
• Investigation of thiolate-mediated reactions.

Main Results:

• Successful demonstration of several new cascade cyclizations.
• Identification of two distinct mechanistic pathways.
• Enantioselective acyl transfer pathway promoted by ABCs.
• Racemic chain mechanism mediated by thiolate nucleophiles.

Conclusions:

• Cascade cyclizations of alpha, beta-unsaturated thioesters can proceed through distinct enantioselective and racemic pathways.
• Amidine-based catalysts (ABCs) enable enantioselective acyl transfer.
• Thiolate nucleophiles mediate a racemic chain mechanism.
• These findings expand the scope and mechanistic understanding of thioester cyclizations.