Table 1. Optimization Studies.
| entry | acylating agent (equiv) | solvent, time | yield of 2 (%)a | yield of 3 (%)a |
|---|---|---|---|---|
| 1b | TrocCl (1.5) | CHCl3, 18 h | 60 (52) | 10 (9) |
| 2b | TCBocCl (1.5) | CHCl3, 18 h | 85 | 0 |
| 3 | Boc2O (1.5) | CHCl3, 7 days | 81 | 0 |
| 4 | Boc2O (5.0) | CHCl3, 6 days | 88 | 0 |
| 5c | Boc2O (1.5) | CHCl3, 18 h | 0 | 96 |
| 6 | Boc2O (1.5) | MeCN, 48 h | 44 | 0 |
| 7 | Boc2O (5.0) | MeCN, 24 h | 85 (68) | 0 |
Yield determined by 19F NMR. Isolated yields in parentheses.
Reaction performed at room temperature with DIPEA (1.5 equiv).
With DMAP (0.3 equiv).
