Entry | Amount of 2a | Catalyst (mol%) | H2O | Solvent | Temp. (˚C) | Time (h) | Yield of 3a (%)b | Yield of 4a (%)b |
1 | 2 eq | BzOH (20) | - | PhMe | 40 | 12 | 36 | 18 |
2 | 2 eq | BzOH (20) | - | PhMe | 50 | 8 | 47 | 23 |
3 | 2 eq | BzOH (20) | - | PhMe | 60 | 6 | 43 | 29 |
4 | 2 eq | BzOH (20) | 1 eq | PhMe | 50 | 8 | 55 | trace |
5 | 2 eq | BzOH (20) | 2 eq | PhMe | 50 | 8 | 63 | trace |
6 | 2 eq | BzOH (20) | 3 eq | PhMe | 50 | 8 | 59 | trace |
7 | 2 eq | BzOH (20) | 2 eq | PhMec | 50 | 8 | 52 | 10 |
8 | 2 eq | BzOH (20) | 2 eq | PhMed | 50 | 8 | 60 | trace |
9 | 2 eq | TsOH (20) | 2 eq | PhMe | 50 | 8 | 27 | 21 |
10 | 2 eq | TfOH (20) | 2 eq | PhMe | 50 | 8 | 44 | trace |
11 | 2 eq | AcOH (20) | 2 eq | PhMe | 50 | 8 | 51 | trace |