A General Method to Access Sterically Hindered and Complex Ethers.

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Catalysis

Background:

• Hindered ethers are valuable compounds in medicinal chemistry and materials science.
• Existing methods for synthesizing hindered ethers often require harsh conditions or expensive catalysts.
• Developing efficient and scalable metal-free synthetic routes remains a key challenge.

Purpose of the Study:

• To develop an efficient, scalable, and metal-free method for synthesizing hindered ethers.
• To explore the utility of anion-binding catalysis in reductive etherification.
• To demonstrate the broad applicability and functional group tolerance of the new method.

Main Methods:

• Reductive etherification using chlorodimethylsilane (CDMS) as a silicon source.
• Employing catalytic amounts of Schreiner thiourea to activate carbonyl compounds.
• Utilizing in situ generated HCl and anion-binding catalysis to form oxocarbenium intermediates.
• Facilitating hydride transfer to form the ether linkage.

Main Results:

• Successfully synthesized hindered ethers with high efficiency using a metal-free catalytic system.
• Demonstrated a broad substrate scope, successfully reacting 89 different substrates.
• Showcased excellent functional group tolerance, including applications with steroids, terpenoids, peptides, and late-stage drug modification (ritonavir).

Conclusions:

• The developed reductive etherification method is efficient, scalable, and metal-free.
• The catalytic system effectively activates carbonyls and promotes ether bond formation.
• This methodology provides a versatile tool for synthesizing complex hindered ethers relevant to various chemical fields.