Table 1. Summary of the effects of reaction parameters on the reaction efficiencya .
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Entry | Variants | Yield (%) | e.e. (%)b |
---|---|---|---|
1 | none | 72 (69)c | 92 |
2 | L1 | 73 | 52 |
3 | L2 | 76 | 42 |
4 | L3 | 31 | 36d |
5 | L4 | 47 | 60 |
6 | L5 | 37 | 58 |
7 | NiBr2 | 52 | 80 |
8 | NiBr2.diglyme | 51 | 84 |
9 | Ni(COD)2 | 31 | 80 |
10e | CsF | 70 | 68 |
11 | PMHS | 57 | 91 |
12 | DMF as solvent | 73 | 66 |
13 | DCE as solvent | n.d. | n.d. |
See the Supporting Information for section 2 experimental details; all reactions were carried out in a 0.1 mmol scale with respect to 2a; corrected GC yields using n-dodecane as an internal standard were reported.
The enantiomeric excesses (e.e.s) were determined using HPLC analysis of the corresponding alcohol after stereospecific oxidation of the boronic ester (see Supplementary Information section 2 for full details).
Isolated yield is shown in the parenthesis.
The opposite enantiomer was enriched.
Reaction time = 12h. DMF = Dimethylformamide; DCE = 1,2-Dichloroethane; RT = room temperature; h = hour. n.d. = not detected; PMHS = Polymethylhydrosiloxane; DEMS = Diethoxy-methylsilane.