Table 1.
entry | [Cu] | ligand | yield (%)b | ee (%)c |
---|---|---|---|---|
1 | Cu(MeCN)4PF6 | BnBox | 49 | 40 |
2 | Cu(MeCN)4BF4 | BnBox | 58 | 42 |
3 | Cu(OAc)2 | BnBox | 60 | 21 |
4 | CuBr | BnBox | 55 | 20 |
5 | CuI | BnBox | 87 | 60 |
6 | CuI | PhBox | 63 | 26 |
7 | CuI | i-PrBox | 57 | 48 |
8 | CuI | t-BuBox | 59 | 26 |
9 | CuI | L1 | 75 | 54 |
10 | CuI | L2 | 82 | 63 |
11 | CuI | L3 | 70 | 61 |
12 | CuI | L4 | 76 | 61 |
Conditions: Acetal 5a (0.12 mmol, 1.0 equiv), [Cu] (0.012 mmol, 10 mol %), L* (0.014 mmol, 12 mol %), HCCPh (6a, 0.15 mmol, 1.2 equiv), Et3N (0.15 mmol, 1.2 equiv), TMSOTf (0.12 mmol, 1.0 equiv), PhMe (0.31 M), 0 °C, 15 h.
Determined by 1H NMR analysis using 1,3,5-trimethoxybenzene as internal standard.
Determined by HPLC analysis using a chiral stationary phase.