Pure (E)- or (Z)-enoylsultams 2 were Oxidized with OsO4/N-Methylmorpholine N-oxide in a stereospecific and highly π-face-selective manner. Acetalization of the resulting 1,2-diols furnished, after purification, the stable, crystalline acetals 6 in >99% d.e. and in 63–74% overall yield from 2. Reductive or hydrolytic cleavage of 6 gave enantiomerically pure alcohols 8 or carboxylic acids 9 with recovery of the sultan auxiliary 1.