Table 2. Optimization of Condition for CDC Reaction of C-1-glucalpropenone 3a with 4-Methylstyrene (5a) to Synthesize 1,2-Disubstituted Glucal 6a at 80 °C for 12 ha.
| entry | catalyst (10 mol %) | oxidant (equiv.) | co-oxidant (equiv.) | solvent | yield of 6a (%)b |
|---|---|---|---|---|---|
| 1 | Pd(OAc)2 | Cu(OAc)2 (2) | - | DMF/DMSO (9:1) | 20 |
| 2 | Pd(OAc)2 | AgOAc (2) | - | DMF/DMSO (9:1) | 50 |
| 3 | Pd(OAc)2 | AgOTf(2) | - | DMF/DMSO (9:1) | 40 |
| 4 | Pd(OAc)2 | Cu(OAc)2(1) | AgOAc (2) | DMF/DMSO (9:1) | 80 |
| 5 | Pd(OAc)2 | CuI (1) | AgOTf (2) | DMF/DMSO (9:1) | 85 |
| 6 | Pd(OAc)2 | Cu(OAc)2(1) | AgOAc (2) | THF | 50 |
| 7 | Pd(OAc)2 | Cu(OAc)2(1) | AgOAc (2) | DMF | 65 |
| 8 | Pd(OAc)2 | Cu(OAc)2(1) | AgOAc (2) | AcCN | 55 |
| 9 | Pd(OAc)2 | Cu(OAc)2(1) | AgOAc (2) | acetone | 60 |
| 10 | Pd(OAc)2 | Cu(OAc)2(1) | AgOAc (2) | DCE | 70 |
| 11 | Pd(OAc)2 | Cu(OAc)2(1) | AgOAc (2) | dioxane | NR |
| 12 | Pd(OAc)2 | Cu(OAc)2 (1) | AgOAc (2) | toluene | NR |
| 13 | PdCl2 | CuI (1) | AgOTf (2) | DMF/DMSO (9:1) | 40 |
| 14 | Pd(PPh3)2Cl2 | CuI (1) | AgOTf (2) | DMF/DMSO (9:1) | 50 |
a
Reaction conditions: Compound 3a (0.18 mmol), 5a (0.2 mmol); solvent used (2 mL); NR = No reaction.
b
Isolated yield.