Table 2.
Synthesis of 1,2,4,5-tetrazines directly from nitriles catalyzed by Ni(OTf)2 or Zn(OTf)2.
| entry | R1 | R2 | catalyst | product | yield[a] |
|---|---|---|---|---|---|
| 1 |
|
|
Ni |
|
95% |
| 2 |
|
|
Zn |
|
59% |
| 3 |
|
|
Zn |
|
24% |
| 4 |
|
|
Zn |
|
32% |
| 5[b] |
|
|
Ni |
|
58% |
| 6 |
|
|
Ni |
|
68% |
| 7 |
|
|
Ni |
|
66% |
| 8 |
|
|
Ni |
|
41% |
| 9 |
|
|
Zn |
|
43% |
| 10 |
|
|
Ni |
|
70% |
| 11 |
|
|
Zn |
|
40% |
| 12[c] |
|
|
Zn |
|
36% |
| 13 |
|
|
Ni |
|
36% |
| 14 |
|
|
Zn |
|
40% |
| 15 |
|
|
Zn |
|
12% |
| 16[c] |
|
|
Zn |
|
30% |
[a]
yields reported after isolation by silica flash chromatography
[b]
the protective groups were lost during oxidative workup
[c]
reaction required 36 hours