Carbohydrates play important roles in cellular signaling, disease progression, and metabolism among other functions. The study of these biological functions has historically been limited by the challenging nature of carbohydrate synthesis. We have developed site-selective acylation and phosphoramidation reactions for carbohydrate trans-1,2,-diols using chiral organocatalysts that can greatly simplify the synthesis of carbohydrates. DFT calculations were performed to determine the interactions governing the site-selectivity of the acylation. We found a novel mode of catalyst-substrate interaction, a cation-n interaction, governed the selectivity. We also found that the same organocatalyst was used for the dynamic kinetic stereoselective acylation of 2-chromanols and Achmatowicz lactols. The privileged nature of acylated Achmatowicz lactols with a high diastereomeric ratio as intermediates in de novo carbohydrate synthesis will be demonstrated.