The regiocontrolled protection of unsymmetrical 1, 2-and 1, 3-diols has been developed. Different types of protected diols are available from the methylene acetal in a one-pot procedure. Highly regioselective protection of diols with a silyl group at the less hindered hydroxy group as well as with a MOM group at the more hindered one were achieved. The reaction conditions are mild without affecting other functional groups including acid-labile ...