Table 5. Screening Conditions for CO2 Reduction.
| entry | catalyst | H–R | b conv (%)a | c conv (%)a | d conv (%)a | e conv (%)a |
|---|---|---|---|---|---|---|
| 1 | [Na(18-c-6)]2[1] | Et3SiH | 0 | 0 | 0 | 0 |
| 2 | [Na(18-c-6)]2[1] | Ph3SiH | 0 | 0 | 0 | 0 |
| 3 | [Na(18-c-6)]2[1] | HBpin | 3 | 1 | 31 | 10 |
| 4 | [Na(18-c-6)]2[1] | HBcat | 0 | 0 | 0 | 0 |
| 5 | [Na(18-c-6)]2[1] | BH3·SMe2 | 0 | 0 | 0 | 0 |
| 6 | [Na(18-c-6)]2[1] | (HBBN)2 | 11 | 0 | 84 | 0 |
| 7 | none | (HBBN)2 | 0 | 0 | 0 | 0 |
| 8 | K3P7 | (HBBN)2 | 0 | 0 | 0 | 0 |
| 9 | [K(18-c-6)]3P7 | (HBBN)2 | 0 | 0 | 0 | 0 |
| 10 | (Me3Si)3P7 | (HBBN)2 | 0 | 0 | 0 | 0 |
a
Determined by 1H NMR spectroscopy, based on C–H bond formation.