Intramolecular Silanoxy-Michael Reactions with Pendant Nitroalkenes: Racemic and Enantioselective

Area of Science:

• Organic Chemistry
• Asymmetric Synthesis
• Catalysis

Background:

• Michael additions are fundamental carbon-carbon bond-forming reactions in organic synthesis.
• Developing enantioselective variants of Michael additions is crucial for synthesizing chiral molecules.
• Silanoxy-Michael additions offer unique reactivity and synthetic utility.

Purpose of the Study:

• To report the first examples of racemic and scalemic di-tert-butyl silanoxy-Michael additions.
• To establish an operationally simple and selective protocol for these additions.
• To develop complementary methods for optimizing yield and enantioselectivity for various substrates.

Main Methods:

• Utilizing a hydrogen-bond donor catalyst for the reaction.
• Employing simple stirring conditions without the need for inert atmosphere or anhydrous techniques.
• Developing specific protocols tailored to different substrates to maximize efficiency.

Main Results:

• Demonstrated the first successful racemic and scalemic di-tert-butyl silanoxy-Michael additions.
• Achieved high selectivity for nitro-olefins.
• Showcased the scalability of the reactions.
• Confirmed the utility of the products as intermediates for synthesizing enantioenriched vicinal amino alcohols.

Conclusions:

• The presented protocol offers a straightforward and effective route to di-tert-butyl silanoxy-Michael adducts.
• The method is robust, scalable, and provides access to valuable chiral building blocks.
• This work expands the toolkit for asymmetric synthesis, particularly for vicinal amino alcohols.