InCl3/Me3SiBr-catalyzed direct coupling between silyl ethers and enol acetates

Area of Science:

• Organic Chemistry
• Catalysis

Background:

• Silyl ethers are versatile protecting groups and synthetic intermediates.
• Direct coupling reactions involving silyl ethers often require harsh conditions or specific activators.
• Enol acetates are readily available and useful precursors in organic synthesis.

Purpose of the Study:

• To develop a novel catalytic system for the direct coupling of enol acetates with silyl ethers.
• To achieve efficient coupling under mild conditions.
• To demonstrate the broad applicability of the method, including with sterically hindered substrates.

Main Methods:

• Utilized a combined Lewis acid catalyst system of Indium(III) chloride (InCl3) and Trimethylsilyl bromide (Me3SiBr).
• Investigated the direct coupling reaction between various enol acetates and silyl ethers.
• Examined the compatibility of the reaction with different functional groups and steric environments.

Main Results:

• The InCl3/Me3SiBr catalyst system effectively promoted the direct coupling of enol acetates with low-reactive silyl ethers.
• The reaction proceeded with high efficiency, tolerating sensitive functional groups such as ketones and aldehydes.
• Sterically hindered silyl ethers, including triethylsilyl (Et3Si), triphenylsilyl (Ph3Si), tert-butyldimethylsilyl (t-BuMe2Si), and triisopropylsilyl (i-Pr3Si) ethers, were successfully employed in the coupling.

Conclusions:

• The developed catalytic system offers a mild and efficient method for the direct coupling of enol acetates and silyl ethers.
• This approach expands the synthetic utility of enol acetates and provides a valuable tool for constructing complex molecules.
• The tolerance of various functional groups and steric hindrance highlights the robustness and broad applicability of this catalytic system.