A General Method to Access Sterically Hindered and Complex Ethers

We report an efficient metal-free and scalable reductive etherification method to synthesize hindered ethers using chlorodimethylsilane (CDMS) and catalytic Schreiner thiourea. The reaction relies on in situ generated HCl and thiourea via anion-binding catalysis, activating carbonyls to form an oxocarbenium intermediate and enabling hydride transfer to create an ether bond. A broad substrate scope (89 substrates) and excellent functional group tolerance including complex ethers of steroids, terpenoids, peptides, and late-stage ritonavir modification have been demonstrated for this method.