Shows the constitutional isomer distribution as result of varying fluoride source and solvent.
| ||||
|---|---|---|---|---|
| Entry | Reagent | Solvent | Yielda% (2) | Yielda% (3) |
| 1 | CsF | DMF | Traces | 0 |
| 2 | TBAF·3H2O | DMF | 9% | 0.6% |
| 3 | TBAF(t-BuOH)4 | DMF | 31 ± 4% | 1.4 ± 0.0% |
| 4 | TBAF(t-BuOH)4 | DMFb | 32%a | 1.4% |
| 5 | TBAF(t-BuOH)4 | PC | 11% | 1% |
| 6 | TBAF(t-BuOH)4 | DMSO | 5% | 1% |
| 7 | TBAF(t-BuOH)4 | PhCl | 12% | 25% |
| 8 | TBAF(t-BuOH)4 | MeCN | 5% | 9% |
| 9 | 1.5 eq. TBAF(t-BuOH)4 | DMF | 30 ± 0% | 0.3 ± 0.1% |
| 10 | 4 eq. TBAF(t-BuOH)4 | DMF | 5 ± 0.2% | 6 ± 0.2% |
a
19F NMR yield using 4-fluorobiphenyl as internal standard. Standard deviation is given for reactions performed in duplicate. Product identities were confirmed from spiking with reference compound.
b
1 h reaction time. PC = propylene carbonate.