Scope study in the DA reaction of 4 and different dienophiles 5a–k.
| ||||
|---|---|---|---|---|
| Entrya | 5 | Conv.b (%) | 6 yieldc (%) | endo : exod |
| 1 | 5a | 100 | 92 | >99 : 1 |
| 2 | 5b | 100 | 85 | >99 : 1 |
| 3 | 5c | 100 | 88 | >99 : 1 |
| 4 | 5d | 78 | 72 | >99 : 1 |
| 5 | 5e | 47 | 46 | >99 : 1 |
| 6 | 5f | 55 | 47 | >99 : 1 |
| 7 | 5g | 67 | 67 | >99 : 1 |
| 8 | 5h | 100 | 87 | >99 : 1 |
| 9 | 5i | — | — | — |
| 10 | 5j | — | — | — |
| 11 | 5k | — | — | — |
a
Reaction conditions: 4 (0.45 M), 5 (0.15 M), C6 and TrCl (0.039 M) in 1.1 mL of water-saturated CDCl3, at 50 °C for 16 h. All aldehydes showed no background reaction in the absence of C6 and TrCl under reaction conditions.
b
Determined by 1H NMR analysis of the crude reaction mixture.
c
Isolated yield.
d
Determined by 1H NMR analysis of the crude reaction mixture according to literature data.21