General allylic C-H alkylation with tertiary nucleophiles

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Methodology

Background:

• Developing efficient methods for C-H functionalization is crucial for streamlined organic synthesis.
• Intermolecular allylic C-H alkylation traditionally faces challenges with substrate scope and selectivity.

Purpose of the Study:

• To establish a general and highly selective palladium-catalyzed method for intermolecular allylic C-H alkylation.
• To expand the scope of olefins and tertiary nucleophiles amenable to this transformation.
• To demonstrate the utility of this method in the diversification of natural products and cascade reactions.

Main Methods:

• Utilized a palladium(II)/bis(sulfoxide) catalytic system for intermolecular allylic C-H alkylation.
• Employed a range of terminal olefins, including aliphatic and aromatic/heteroaromatic types, and 1,4-dienes.
• Investigated the scope of tertiary nucleophiles, including those with latent functional groups.

Main Results:

• Achieved good yields (average 64%) with excellent regio- (linear:branched >20:1) and stereoselectivity (E:Z >20:1).
• Demonstrated broad substrate scope for both olefins and tertiary nucleophiles.
• Successfully applied the method to rapidly diversify phenolic natural products and in an allylic C-H alkylation/Diels-Alder cascade.

Conclusions:

• Developed a versatile and selective palladium-catalyzed intermolecular allylic C-H alkylation.
• The methodology enables efficient synthesis of complex structures, including natural product scaffolds.
• Highlights the potential of C-H activation strategies for synthetic streamlining and molecular diversification.