Table 1. Amounts of the Cys Catalyst Used in Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones/thiones (4–9).
| entry | cat. mol % | yield %a | entry | cat. mol % | yield %a |
|---|---|---|---|---|---|
| 1 | 3 | 21 | 5 | 13 | 84 |
| 2 | 6 | 41 | 6 | 15 | 98 |
| 3 | 9 | 58 | 7 | 16 | 98 |
| 4 | 11 | 76 | 8 | 17 | 98 |
Isolated yields based on 4, 1(1 mmol), 2a (1.5 mmol), and 3a (1 mmol) in a mixture of water and ethanol (3:1 ratio) by microwave irradiation condition, 3 min.