Lithium diphenylcuprate treatment of methyl 2,3-anhydro-4,6-O-benzylidene-D-pyranosides in which the anomeric substituent and the three-membered rings arecisoriented furnished the expectedtrans-diaxial opening products. When the relationship between the anomeric group and the epoxide wastrans, the same experimental conditions led only to recovered starting material. Cyano cuprates of the type R2CuCNLi2added stereoselectively to carbohydrate ketones at C-2 and C-3 from the opposite side relative to the anomeric substituent.