Optically active polyhydroxy trans-1,2-amino alcohols were efficiently synthesized in good to excellent yields by the Petasis boronic-Mannich reaction of an amine, an organoboronic acid, and a chiral lactol, which was prepared from D-araboascorbic acid or its diastereomer. Further transformations of the resulting Petasis products were investigated in detail to obtain chiral building blocks containing three continuous stereogenic centers.