Table 1 Optimization of the reaction conditions for the homocoupling of 1a to 2a.
From: Synthesis of highly substituted alkenes by sulfur-mediated olefination of N-tosylhydrazones
| ||||||
|---|---|---|---|---|---|---|
Entry | Base (eq.) | S8 / (eq.) | Solvent (conc.) | T / °C | t / min | Conversion of 1a / % |
1 | NaH (1.20) | 0.28 | DMSO-d6 (0.5 M) | 130 | 60 | 100 |
2 | NaH (1.20) | 0.28 | DMSO-d6 (0.5 M) | 80 | 300 | 66 |
3 | NaH (1.20) | 0.28 | DMSO-d6 (0.5 M) | 90 | 300 | 86 |
4 | NaH (1.20) | 0.28 | DMSO-d6 (0.5 M) | 100 | 30 | 82 |
5 | DBU (1.20) | 0.28 | DMSO-d6 (0.5 M) | 100 | 30 | 66 |
6 | K2CO3 (1.20) | 0.28 | DMSO-d6 (0.5 M) | 100 | 20 | 100 |
7 | Cs2CO3 (1.20) | 0.28 | DMSO-d6 (0.5 M) | 100 | 20 | 100 |
8 | K2CO3 (1.20) | 0.28 | GBL (0.5 M) | 100 | 20 | n.d. a) |
9 | K2CO3 (1.20) | 0,28 | DMF (0.5 M) | 100 | 20 | 76 |
10 | K2CO3 (1.20) | 0.28 | NMP (0.5 M) | 100 | 20 | 88 |
11 | K2CO3 (1.20) | 0.28 | DMSO-d6 (1 M) | 100 | 20 | 100 |
12 | K2CO3 (1.20) | 0.28 | DMSO-d6 (0.25 M) | 100 | 20 | 100 |
13 | K2CO3 (1.20) | 0.1875 | DMSO-d6 (0.5 M) | 100 | 20 | 100 a) |
14 | K2CO3 (1.20) | 0.1375 | DMSO-d6 (0.5 M) | 100 | 20 | 100 a) |
15 | K2CO3 (1.20) | 0.25 | DMSO (0.5 M) | 100 | 30 | 100 |
