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. Author manuscript; available in PMC: 2010 Dec 30.
Published in final edited form as: J Am Chem Soc. 2009 Dec 30;131(51):18343–18357. doi: 10.1021/ja9053948

Table 3.

Selected Optimization Studies

graphic file with name nihms-161072-t0039.jpg
entry ligand solvent temp conc. eeb yieldc of 21 yieldc of 22
1 (R,R)-L1 Toluene 23 °C 0.1 M 31% 73% 0
2 (R,R)-L2 Toluene 23 °C 0.1 M 61% 73% 2%
3 (R,R)-L3 Toluene 23 °C 0.1 M 60% 85% 1%
4 (R,R)-L4 Toluene 23 °C 0.1 M 85% 88% 0
5 (R,R)-L4 CH2Cl2 23 °C 0.1 M 84% 64% 26%
6 (R,R)-L4 1,4-Dioxane 23 °C 0.1 M 80% 99% 0
7 (R,R)-L4 DME 23 °C 0.1 M 84% 87% 7%
8 (R,R)-L4 THF 23 °C 0.1 M 81% 85% 1%
9 (R,R)-L4 Toluene 4 °C 0.1 M 87% 91% 2%
10 (R,R)-L4 Toluene −10 °C 0.1 M 83% 84% 6%
11 (R,R)-L4 Toluene 4 °C 0.3 M 85% 94% 4%
12 (R,R)-L4 Toluene 4 °C 0.025M 87% 92% 0%
13d (R,R)-L4 Toluene 4 °C 0.3 M 85% 88% 5%
a

Unless otherwise indicated, all reactions were performed on a 0.3 mmol scale at 23 °C employing 2.5 mol% 20 and 5.5 mol% ligand.

b

The ee values were determined by chiral GC.

c

The yields were determined by quantitative GC analysis using decane as internal reference.

d

1.0 mol% 20 and 5 mol% L4 were used.