Methylene acetal formation from 1,2- and 1,3-diols using an O,S-acetal, 1,3-dibromo-5,5-dimethylhydantoin, and BHT.

A mild and efficient method for formation of methylene acetals from 1,2- and 1,3-diols using methoxymethylphenylsulfide, 1,3-dibromo-5,5-dimethylhydantoin (DBDMH), and dibutylhydroxytoluene (BHT) is described. The use of BHT in this process suppresses side reactions and enables high-yielding formation of methylene acetals of various diols, including carbohydrate-type substrates.