Synthesis of oxetane and azetidine ethers as ester isosteres by Brønsted acid catalysed alkylation of alcohols with 3-aryl-oxetanols and 3-aryl-azetidinols

3-Aryloxetan-3-ols and 3-arylazetidin-3-ols can be selectively activated to form carbocations and allow reaction with alcohols to form ethers with the 4-membered heterocycles.