Table 2. Synthesis of N-Benzyl α-Trifluoromethylthioamide from N-Acylpyrazoles under Flow Conditionsa.
| entry | solvent | base | T (°C) | resid time (min) | yieldb (%) |
|---|---|---|---|---|---|
| 1 | THF | PS | 25 | 30 | 0 |
| 2 | THF | PS | 25 | 15 | 0 |
| 3 | THF/CH3CN (1:1) | PS | 30 | 30 | 20 |
| 4 | THF/CH3CN (1:1) | PS | 30 | 15 | 15 |
| 5 | THF/CH3CN (1:1) | TEA | 30 | 30 | 61 |
| 6 | THF/CH3CN (1:1) | TEA | 30 | 15 | 41 |
| 7 | THF/CH3CN (1:1) | TEA | 45 | 15 | 52 (51) |
| 8 | THF/CH3CN (1:1) | TEA | 60 | 15 | 75 (73) |
| 9 | THF/CH3CN (1:1) | TEA | 90 | 15 | 50 |
| 10c | THF/CH3CN (1:1) | TEA | 45 | 15 | 83 |
| 11d | THF/CH3CN (1:1) | TEA | 45 | 15 | 85 (83) |
a
Reaction conditions: 0.2 mol/equiv of TEA was used.
b
Yield determined by 19F NMR analysis of the crude reaction product with α,α,α-CF3C6H5 as internal standard and in parentheses as yield after chromatographic purification.
c
0.35 mol/equiv of TEA.
d
0.5 mol/equiv of TEA.