Table 3 Comparison of various employed conditions for the aza-Diels–Alder reaction.
Entry | Catalyst | Type | Conditions | Yields (%) | Ref. |
|---|---|---|---|---|---|
1 | Chiral phosphoric acid | Diastereoselective | 1,2-Dichloroethane, 50 °C, 24–96 h | 11–93 | |
2 | Chiral phosphoric acid | Diastereoselective | Toluene, − 10 °C, 10–55 h | 59–89 | |
3 | AgOTf | Racemic product | H2O, rt., 2–3 h | 51–92 | |
4 | Dy(OTf)3 | Diastereoselective | MeCN, rt., 24 h | 54–92 | |
5 | Fluorenone | Racemic product | Air, MeNO2, rt., 2 h | 86–96 | |
6 | CF3COOH | Diastereoselective | MW, MeCN, 60 °C, 15 min | 39–59 | |
6 | Ce/Hal-TCT-IDA | Racemic product | CH2Cl2, rt., 12–48 h | 75–91 | This work |
