Table 2.
Tandem oxidative cyclization of compound 8.
| Sr. No. | Reaction conditions | Time (h) | Yielda of 1 (%) |
|---|---|---|---|
| 1 | I2 (0.1 equiv), TBHP (2 equiv), EtOH, Ar, reflux | 48 | No reaction |
| 2 | CAN (2.5 equiv), CH3CN, Ar, 0 °C | 2 | Decomposed |
| 3 | Mn(OAc)3·2H2O (4 equiv), CH3CN, Ar, reflux | 5 | Decomposed |
| 4 | KHMDS (1.05 equiv), THF, Ar, 0 °C to r.t | 2 | Decomposed |
| 5 | Ru(bpz)3(PF6)2 (0.1 equiv), (NH4)2S2O8 (2 equiv), CH3CN, Ar, blue LED, r.t | 24 | Decomposed |
| 6 | [Ir(dtbbpy)(ppy)2[PF6] (0.1 equiv), BrCCl3 (2 equiv), CH3CN, Ar, blue LED, r.t | 36 | Decomposed |
| 7 | Acridinium (0.1 equiv), TBHP (2 equiv), CH3CN, Ar, blue LED, r.t | 48 | Decomposed |
| 8 | PIFA (1.2 equiv), HFIP, Ar, r.t | 6 | 47 |
| 9 | PIFA (1.2 equiv), H3PO4 (0.1 equiv), HFIP, Ar, r.t | 4 | Trace amounts |
| 10 | PIFA (1.2 equiv), (±)-BINOL phosphoric acid (0.05 equiv), HFIP, Ar, r.t | 3 | 74 |
aIsolated yield after column chromatography.