Table 2. Thiadiazine Formation with 3 and Various Aldehydes.
Entry | R | 4a–j | Yielda |
---|---|---|---|
1 | Ph | 4a | 66%b |
2 | Me | 4b | 59% |
3 | Et | 4c | 56% |
4 | 2,4-Cl2C6H3 | 4d | 70% |
5 | 4-NCC6H4 | 4e | 41% |
6 | 4-MeCO2C6H4 | 4f | 57% |
7 | 4-CF3C6H4 | 4g | 65% |
8 | 2-BrC6H4 | 4h | 45% |
9 | 4-AcOC6H4 | 4i | 48% |
10 | 3-MeOC6H4 | 4j | 62% |
11 | 3-thiophene | 4k | 30% |
Isolated yield after chromatography on SiO2.
Reaction was performed using TFA (2.5 equiv), HFIP, 35–40 °C, 17 h.