Table 1.
Optimization of the reaction conditions for synthesis of 3a from BiPh3 (1a) and (pinB)2 (2).
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| Entry | 2 (mmol) | Additive (equiv) | Solvent (mL) | Temp (°C) | Yield 3a (%)a |
Recovery 1a (%)a |
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| 1 | 2.0 | – | BTF (0.4) | 80 | 68 (53) | trace |
| 2 | 0.5 | NaOMe (1.2) | BTF (0.2) | 80 | N. D. | 62 |
| 3 | 3.0 | – | BTF (0.4) | 80 | 62 | trace |
| 4 | 0.5 | – | BTF (0.4) | 80 | 36 | 30 |
| 5b | 2.0 | – | BTF (0.4) | 80 | 58 | trace |
| 6 | 2.0 | – | BTF (0.4) | 60 | 59 | trace |
| 7 | 2.0 | – | BTF (0.4) | 100 | 61 | trace |
| 8 | 2.0 | (PhS)2 (0.01) | BTF (0.4) | 80 | 63 | trace |
| 9 | 2.0 | – | CHCl3 (0.4) | 80 | 36 | 17 |
| 10 | 2.0 | – | CH3CN (0.4) | 80 | 51 | 17 |
| 11 | 2.0 | – | DMF (0.4) | 80 | 38 | 48 |
| 12 | 2.0 | – | DMSO (0.4) | 80 | 18 | 80 |
| 13 | 2.0 | – | EtOH (0.4) | 80 | 45 | 16 |
aYields were determined by 1H NMR spectroscopy based on 1a as three transferable aryl groups (internal standard: 1,3,5-trioxane). Isolated yield was shown in parentheses. bUnder O2 (0.1 MPa).