Table 1.
Synthesis of C2‐modified methyl glycosides 33–40 through C2‐triflate inversion.
| Entry | Triflate | Cond.[a] | Substitution product |
Yield [%] |
Side products (yield [%]) |
|---|---|---|---|---|---|
| from d‐ribo‐ to d‐arabino‐configured | |||||
| 1 | 29 | A (N3) | 34 | 93 | – |
| 2 | 29 | B (TBAF) | 38 | 71 | – |
| 3 | 29 | C (CsF) | 38 | 86 | – |
| from d‐arabino‐ to d‐ribo‐configured | |||||
| 4 | 30 | A | 33 | 86[b] | 51 [b] |
| 5 | 30 | B | 37, β only | 42 | 30α (17) |
| 6 | 30 | C | 37 | 63 | 52 f (17) |
| from d‐xylo‐ to d‐lyxo‐configured | |||||
| 7 | 32α | A[c] | 35α | 67 | 53α (12), 55 (7) |
| 8 | 32α | B[d] | 39α | 44 | 28 (17) |
| 9 | 32α | C[e] | 39α | – | 54α (57), 55 (21) |
| 10 | 32β | A[c] | 35β | – | 53β, (30) |
| 11 | 32β | B[d] | 39β | – | 54β (18), 56[ g] |
| 12 | 32β | C | 39β | – | 54β (47), 40β (10) |
| from d‐lyxo‐ to d‐xylo‐configured | |||||
| 13 | 31 | A,B,C | 36/40 | – | 56[ g] |
[a] Reagents and conditions: A) 0.2 m solution in DMF, NaN3 (5 equiv), 80 °C, 2 h; B) 0.2 m solution in THF, TBAF (2.5 equiv), 0–20 °C, overnight; C) 0.35 m solution in tert‐amyl alcohol, CsF (4 equiv), 90 °C, overnight. [b] Combined yield of 33 and 51 as a 4:1 mixture. [c] Overnight. [d] 70 °C, 5 h for entry 8, overnight for entry 11. [e] 110 °C overnight. [f] α/β=88:12. [g] Yield not determined.