Table 1. Reaction Optimizationa.
| Oxidant | Equiv (1a/2a/Ox.) | Solvent (Temp, °C) | Yield (%)a | |
|---|---|---|---|---|
| 1 | O2b | 1:1.5:– | DMF (100) | 0 |
| 2 | KIO4c | 1:1:1.5 | HFIP (40) | 0 |
| 3 | PIDA | 1:1:1 | HFIP (40) | 51 |
| 4 | PIDAb | 1:2:1 | HFIP (40) | 49 |
| 5 | PIDAc | 1:2:1 | HFIP (40) | 62 |
| 6 | PIDA | 1:1:2 | HFIP (40) | 45 |
| 7 | PIDA | 1:1.5:2 | HFIP (40) | 65 |
| 8 | PIDA | 1:3:2 | HFIP (40) | 65 |
| 9 | PIDA | 1:2:1 | HFIP (40) | 73 |
| 10 | PIFA | 1:2:1 | HFIP (40) | 41 |
| 11 | IBX | 1:2:1 | HFIP (40) | 0 |
| 12 | HTIB | 1:2:1 | HFIP (40) | 54 |
| 13 | PIDA | 1:2:1 | TFE (40) | 58 |
| 14 | PIDA | 1:2:1 | TCE (40) | 54 |
| 15 | PIDA | 1:2:1 | CH3CN (40) | 50 |
| 16 | PIDA | 1:2:1 | HFIP (50) | 60 |
| 17 | PIDA | 1:2:1 | HFIP (60) | 58 |
| 18 | PIDA | 1:2:1 | HFIP (60)d | 68 |