Scheme 2. Synthesis of glycosidic linkage variants via traditional glycosylations using the glycosyl donor as an electrophile. Reagents and conditions: (a) Ph₂SO, Tf₂O, TBP, CH₂Cl₂, –45 °C, then add 13, 87% (β only); (b) Ph₂SO, Tf₂O, TBP, CH₂Cl₂, –45 °C, then add 14, 60–78% combined yield of separable anomers (2 equiv. 14 → 2 : 1 to 4 : 1 β/α-19; 2 equiv. 17 → 1 : 6 β/α-19); (c) (COBr)₂, DMF, TBP, CH₂Cl₂, 0 °C, 74%; (d) X = O: 15, AgOTf, TBP, CH₂Cl₂, –40 °C, 69% isolated yield of β-anomer (>20 : 1 β/α ratio in crude product); (e) X = S: 16, NaH, 2.5 : 1 THF/DMF, 0 °C, 69%. TBP = 2,4,6-tri-tert-butylpyridine.