Table 1 Optimization of the reaction conditionsa
From: An unexpected synthesis of azepinone derivatives through a metal-free photochemical cascade reaction
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|---|---|---|---|---|---|
Entry | Substrate | Light source | Additive | Solvent | Yield of 5a (%)b |
1 | 1a | UVA | — | THF | 17 |
2 | 1a | blue LEDs | — | THF | 40 |
3 | 1a | blue LEDs | — | toluene | 14 |
4 | 1a | blue LEDs | — | DCE | 9 |
5 | 1a | blue LEDs | 10 eq. H2O | THF | 46 |
6 | 2a | blue LEDs | 10 eq. H2O | THF | n.d. |
7 | 3a | blue LEDs | 10 eq. H2O | THF | 65 |
8 | 3a | blue LEDs | 30 eq. H2O | THF | 45 |
9 | 3a | blue LEDs | — | THF/H2O = 4/1 | 28 |
10 | 3a | blue LEDs | 10 eq. H2O; 0.5 eq. TsOH | THF | 83 |
11 | 3a | blue LEDs | 10 eq. H2O; 1.0 eq. TsOH | THF | 63 |
12 | 3a | blue LEDs | 10 eq. H2O; 0.05 eq. TsOH | THF | 69 |
13 | 3a | blue LEDs | 10 eq. H2O; 0.5 eq. MsOH | THF | 69 |
14 | 3a | blue LEDs | 10 eq. H2O; 0.5 eq. AcOH | THF | 59 |
15 | 3a | blue LEDs | 10 eq. H2O; 0.5 eq. HCl | THF | 69 |
16 | 3a | blue LEDs | 10 eq. H2O; 0.5 eq. Zn(OTf)2 | THF | 37 |
17 | 3a | in the dark | 10 eq. H2O; 0.5 eq. TsOH | THF | n.d. |
