Table 2. Reaction Screening and Optimization^a.

entry	precursor loading (μmol)	solvent	temperature (°C)	TEb (%)	RCYc (%)
1	60	NMP	100	50	50
2	60	DMA	100	45	35
3d	60	DMF	100	69 ± 3	67 ± 5
4e	60	DMF	110	61 ± 12	58 ± 12
5	60	DMF	120	50	47
6	60	NMP	80	50	41
7f	60	NMP	100	53	49
8g	60	DMF	100	97	2
9h	60	DMF	110	6	5
10i	60	DMF	110	42	31
11j	60	DMF	100	6	0.01
12	30	DMF	100	48	45
13	15	DMF	100	48	40
14d,k	30	DMF	110	35 ± 3	33 ± 4

^aUnless otherwise stated, reactions were carried out using the following standard conditions and are n = 1: solvent (600 μL); 1a (19.6 μL, 60 μmol, 0.1 M); CuTC (5.3 μmol, 8.7 mM); TMEDA (0.8 mmol, 1.3 M); temperature: 100 °C; time: 5 min.

^bTE (trapping efficiency): percentage of total activity that remains in solution after acidifying the reaction mixture.

^cRCY (radiochemical yield): percentage of total activity converted to [¹¹C]1b.

^dn = 3.

^en = 2.

^fTMEDA (240 μL, 1.6 mmol, 2.6 M).

^gDMEDA as the base.

^hCuTC (0.1 mg, 0.52 μmol, 0.87 mM).

ⁱCuTC (5.4 mg, 28.6 μmol, 47.0 mM).

^jCuI as the Cu(I) source.

^kHalf-quantity of all reagents: DMF (300 μL); 1a (9.8 μL, 30 μmol); CuTC (2.7 μmol); TMEDA (0.4 mmol).