Table 3. Stepwise Reaction of 1a–c and 11 to 12a–c, 13a–c, and 14a–c.
| entry | 1 | R1 | 12 | yield (%) | 13 | yield (%) | 14 | yield (%) |
|---|---|---|---|---|---|---|---|---|
| 1 | 1a | H | 12a | 82a | 13a | 99 | 14a | 61c |
| 2 | 1b | Me | 12b | 73a | 13b | 91 | 14b | 89c |
| 3 | 1c | Cl | 12c | 70b | 13c | 95 | 14c | 74d |
The reaction with piperidine (0.2 equiv) in benzene at r.t.
The reaction with piperidine (0.2 equiv) and acetic acid (1.0 equiv) in benzene at 80 °C.
The reaction with DDQ at r.t. in dichloromethane.
The reaction with DDQ at 80 °C in 1,2-dichloroethane.