Table 2. Optimization for the Synthesis of Product 3a.

| entry | cat. (mol %) | additive (mol %) | solvent | yielda (%) |
|---|---|---|---|---|
| 1 | CuI (10) | pyridine (30) | EtOH | 18 |
| 2 | CuI (10) | pyridine (30) | CH2Cl2 | 45 |
| 3 | CuI (10) | 1,10-phen (30) | CH2Cl2 | 56 |
| 4 | CuI (5) | 1,10-phen (15) | CH2Cl2 | 42 |
| 5 | CuI (20) | 1,10-phen (60) | CH2Cl2 | 56 |
Isolated yield.