Table 1 Optimization of the synthesis of CNG-DPH 3 and (imidazo[4,5-d]imidazole-2,5-diylidine)dicyanamide 4.
From: Synthesis, X-ray crystallography and antimicrobial activity of 2-cyanoguanidinophenytoin
Entry | Base (n equivalent) | Solvent | Cyanoguanidine (n equivalent) | Time (h) | Yield% | |
|---|---|---|---|---|---|---|
3 | 4 | |||||
1 | KOH (1) | EtOH | 1.0 | 1 | 57 | 18 |
2a | KOH(0.5) | EtOH | 2.5 | 4 | Undetectedb | 52 |
3 | KOH (2.5) | EtOH | 1.0 | 1 | 63 | 15 |
4 | KOH (4) | EtOH | 2.5 | 1 | 52 | 24 |
5a | KOH (4) | EtOH | 1.0 | 1 | 65 | Undetectedb |
6 | NaOH (4) | EtOH | 1.0 | 1 | 60 | 10 |
7 | MeONa (2.5) | MeOH | 1.0 | 1 | 67 | 12 |
8 | EtONa (2.5) | EtOH | 1.0 | 1 | 72 | 8 |
9c | EtONa (4) | EtOH | 1.0 | 1 | 80 | 5 |
10 | EtONa (5) | EtOH | 1.0 | 1 | 78 | 5 |
