Racemic 1, 3-alkanediols (rac-1) undergo an enantioselective acetalization by treatment with l-methone enol trimethylsilyl ether (10) in the presence of trifluoromethanesulfonic acid (10 mol%) to give thermodynamically less stable spiroacetal 3 (derived from 1) in preference to spiroacetal 4 (derived from ent-1). The kinetically controlled acetalization is applied to a novel kinetic resolution of racemic 1, 3-alkanediols: Optically active diols ent-1 of 55–95% ...