Table 1.
| |||
---|---|---|---|
entry | oxygen source | metal catalyst | % yielda |
1 | TEMPO | none | 11 |
2 | Oxoammoniumb | none | 19 |
3 | TEMPO | Sc(OTf)3 | 17 |
4 | TEMPO | Zn(NTf2)2 | 12 |
5 | TEMPO | [Fe(dmf)3Cl2][FeCl4] | 72 |
6 | TEMPO | Co(salen) | 75 |
7 | TEMPO | CuCl2 | 82 |
Yield determined by 1H NMR analysis relative to internal standard.
Added as a solution in DMF by syringe pump over 1h.