Asymmetric 1,3-Dioxane Synthesis by Using Bifunctional Thiourea Catalysis.

Area of Science:

• Organic Chemistry
• Asymmetric Synthesis
• Catalysis

Background:

• The hemiacetalization/oxy-Michael addition cascade is effective for synthesizing 1,3-dioxanes and optically active 1,3-diols, crucial in pharmaceuticals.
• Catalytic enantioselective reactions using carboxylic acid derivatives as Michael acceptors were previously unreported.

Purpose of the Study:

• To develop a catalytic asymmetric hemiketalization/oxy-Michael addition cascade reaction.
• To utilize phenyl trifluoromethyl ketone and chiral bifunctional thiourea catalysts.
• To expand the scope to include carboxylic acid derivatives as Michael acceptors.

Main Methods:

• Employing chiral bifunctional thiourea catalysts for asymmetric catalysis.
• Utilizing phenyl trifluoromethyl ketone as the carbonyl reagent.
• Investigating the cascade reaction with δ-hydroxy-α,β-unsaturated ketones and carboxylic acid derivatives.

Main Results:

• Achieved good yields with high enantio- and diastereoselectivity.
• Demonstrated applicability to both ketone and carboxylic acid derivative substrates.
• Established a flexible synthetic route for compounds with high oxidation states.

Conclusions:

• Developed a novel catalytic asymmetric hemiketalization/oxy-Michael addition cascade.
• Successfully employed chiral bifunctional thiourea catalysts for high selectivity.
• Expanded the synthetic utility to carboxylic acid derivatives, offering greater flexibility.