Copper(I)-catalyzed asymmetric 1,6-conjugate allylation

Area of Science:

• Organic Chemistry
• Catalysis
• Asymmetric Synthesis

Background:

• Catalytic asymmetric conjugate allylation of unsaturated carbonyl compounds is challenging due to dominant 1,2-addition.
• Achieving high asymmetric induction in these reactions remains a significant hurdle.

Purpose of the Study:

• To develop a novel catalytic system for asymmetric 1,6-conjugate allylation.
• To investigate the role of ligand structure in achieving high enantioselectivity.

Main Methods:

• Utilized a copper(I)-NHC (N-heterocyclic carbene) complex as the catalyst.
• Employed 2,2-dimethyl-6-alkenyl-4H-1,3-dioxin-4-ones as substrates.
• Investigated the effect of phenolic hydroxyl groups on NHC ligands.

Main Results:

• Successfully achieved asymmetric 1,6-conjugate allylation with moderate to high yields and high enantioselectivity.
• Demonstrated tolerance of various aryl and alkyl groups at the δ-position.
• Showcased the utility of both 2- and 3-substituted allylboronates as reagents.
• Highlighted the synthetic versatility of the resulting products through further transformations.

Conclusions:

• The developed copper(I)-NHC catalyzed system is effective for asymmetric 1,6-conjugate allylation.
• The phenolic hydroxyl group in NHC ligands is crucial for high enantioselectivity.
• The products are synthetically valuable intermediates for further chemical modifications.