Stereoselectivity for the reduction of the lactols can be modulated by the correct choice of protective groups.
Lactols possessing TBDMS protective groups afford the 伪-anomer, whereas their benzylated congeners provide the 尾-anomer.
This change in stereoselectivity is observed in carbohydrate derivatives possessing 2,3-trans substituents.
The phenomenon is observed only when the C2 and C3 protective groups are the same (both benzyl or both TBDMS).