Synthesis of S,S,O-orthoesters and 1,1-difluoroalkyl ethers via reaction of peroxides with lithiated 1,3-dithianes.

Alkyl tetrahydropyranyl peroxides (ROOTHP) transfer alkoxide (OR) to lithiated 1,3-dithianes. The derived S,S,O-orthoesters undergo fluorodesulfurization with HF/pyridine and N-bromosuccinamide (NBS) to furnish difluoromethyl ethers. The overall protocol can be applied to synthesis of both terminal (ROCF2H) and internal (ROCF2R') ethers. Application of the same set of reactions to a lithiated tris(alkylthio)alkane is shown to generate a trifluoromethyl ether.