Table 1. Optimization of the Reaction Conditions.
entry | NH3 source | N3 source | solvent | base (equiv) | temp, time | yield (%) |
---|---|---|---|---|---|---|
1 | NH4OH | TMSN3 | MeOH | – | RT, 8 h | traces |
2 | NH4OH | TMSN3 | MeOH | – | RT, 18 h + 60 °C, 18 h | 31 |
3 | NH4OH | TMSN3 | MeOH | – | 60 °C, 18 h | 48a |
4 | NH4OH | NaN3 | MeOH | – | RT, 18 h + 50 °C, 18 h | 35 |
5 | NH4OH | TMSN3 | MeOH | NaOMe (1.0) | RT, 18 h + RT, 18 h | 22 |
6 | NH4OH | NaN3 | MeOH | NaOMe (1.0) | RT, 18 h + 50 °C, 18 h | 16 |
7 | NH4OH | NaN3 | MeOH | Et3N (1.0) | RT, 18 h + 60 °C, 18 h | 9 |
8 | NH4Cl | NaN3 | MeOH/H2O (3:1) | Et3N (1.0) | RT, 18 h + RT, 18 h | 59 |
9 | NH4Cl | NaN3 | MeOH/H2O (3:1) | Et3N (1.0) | RT, 18 h + 60 °C, 18 h | 47 |
10 | NH4Cl | NaN3 | MeOH/H2O (3:1) | Et3N (1.0) | RT, 18 h + 40 °C, 18 h | 50 |
11 | NH4Cl | NaN3 | MeOH:H2O (3:1) | NaOMe (1.0) | RT, 18 h + 40 °C, 18 h | 27 |
12 | NH4Cl | NaN3 | MeOH/H2O (3:1) | NH4OH (1.0) | RT, 18 h + 40 °C, 18 h | 29 |
13 | NH4Cl | NaN3 | MeOH/H2O (3:1) | NaOMe (0.1) | RT, 18 h + 40 °C, 18 h | 55 |
14 | NH4Cl | NaN3 | MeOH/H2O (3:1) | NH4OH (0.1) | RT, 18 h +50 °C, 18 h | 67 |
The product was obtained as the free tetrazole.