Table 1. Optimization of Radiofluorination of 1-B(OH)2 To Form [18F]-4-Fluoroacetophenone 2.
| entrya | QMA eluent | [Cu] | RCCb (%) |
|---|---|---|---|
| 1 | K2CO3 | Cu(OTf)2 | 0 |
| 2 | K2CO3 | Cu(OTf)2(py)4 | 0 |
| 3 | K2CO3 | (MeCN)4CuOTfc | 0 |
| 4 | PPTS | Cu(OTf)2 | 48 ± 2 |
| 5 | KOTf/K2CO3 | Cu(OTf)2 | 51 ± 5d |
| 6 | KOTf/K2CO3 | none | <1 |
| 7 | KOTf/K2CO3 | Cu(OTf)2 | <4e |
| 8 | KOTf/K2CO3 | Cu(OTf)2 | 61 ± 8 |
| 9 | KOTf/K2CO3 | Cu(OTf)2(py)4 | 51 ± 7 |
| 10 | KOTf/K2CO3 | Cu(OTf)2 | 10 ± 2f |
a
Conditions: 1:5:125 1-B(OH)2/Cu(OTf)2/py at 4 mM concentration of the boronic acid precursor in DMF, K18F, 110 °C, 20 min.
b
RCC was determined by radio-TLC (n ≥ 2).
c
Other Cu sources were tested as well. See the SI.
d
Best conditions 1:5:125:0.1 1-B(OH)2/Cu(OTf)2/py/PPTS.
e
Pyridine omitted.
f
Reaction automated using a GE TRACERLab FXFN.