Table 1. Optimization studies and control experimentsa.
Entry | Deviation | [%] Yield of 3ab |
---|---|---|
1 | None | 82 |
2 | No base, no light | 0 |
3 | Under air instead of N2 | 0 |
4 | 427 nm or 456 nm light | 0 |
5 | Na2CO3 instead of Cs2CO3 | 56 |
6 | TMG instead of Cs2CO3 | 78 |
7 | 1 equiv. Cs2CO3 | 37 |
Reactions performed over 4 hours in 1 mL of CH3CN using 0.15 mmol of 1a, 0.45 mmol of 2a, and base (2 equiv.) under irradiation by a Kessil lamp (λmax = 390 nm, irradiance = 100 mW cm−2).
Yield of 3a determined by 1H NMR analysis of the crude mixture using dibromomethane as the internal standard.