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. Author manuscript; available in PMC: 2017 Jan 13.
Published in final edited form as: J Am Chem Soc. 2015 Dec 28;138(1):369–374. doi: 10.1021/jacs.5b11120

Table 2.

Studies of the Mixed-ligand Conditions and Control Experimentsa

graphic file with name nihms787187t3.jpg
Entry Catalyst/Ligand Additives Solvent Yieldb er(R:S)c
1 [Rh(cod)(CH3CN)2]BF4/(R)-xyl-SDP none THF 46% (63%) 99.5:0.5
2 [Rh(cod)(CH3CN)2]BF4/(R)-xyl-SDP none 1,4-dioxane 51% (85%) 99:1
3 [Rh(cod)2]BF4/(R)-xyl-SDP none 1,4-dioxane 53% (90%) 99:1
4d [Rh(cod)2]BF4/(R)-xyl-SDP none 1,4-dioxane 55% (85%) 99:1
5 [Rh(cod)2]BF4/(S)-xyl-BINAP none 1,4-dioxane 79% 96:4
6 [Rh(cod)2]BF4/(R)-xyl-SDP : (S)-xyl-BINAP = 1:1 none 1,4-dioxane 63% 97:3
7 [Rh(cod)2]BF4/(R)-xyl-SDP : (R)-xyl-BINAP = 1:1 none 1,4-dioxane 75% 45:55
8 [Rh(cod)2]BF4/(R)-xyl-SDP : (rac)-xyl-BINAP = 1:1 none 1,4-dioxane 74% 66:34
9d [Rh(cod)2]BF4/(R)-xyl-SDP : (S)-xyl-BINAP = 1:1 none 1,4-dioxane 72% 97.2:2.5
10d [Rh(cod)(CH3CN)2]BF4/(R)-xyl-SDP: (S)-xyl-BINAP = 1:1 none 1,4-dioxane 61% 97:3
11d [Rh(cod)2]BF4/(R)-xyl-SDP : (S)-xyl-BINAP = 2:1 none 1,4-dioxane 60% 98.5:1.5
12d [Rh(cod)2]BF4/(R)-xyl-SDP : (S)-xyl-BINAP = 5:1 none 1,4-dioxane 54% 99:1
variations from entry 9
13 w/o Rh catalysts none 1,4-dioxane 0% N/A
14 w/o ligand none 1,4-dioxane 0% N/A
15 w/o catalyst & ligand none 1,4-dioxane 0% N/A
16 w/o catalyst & ligand 20 mol% ZnCI2 1,4-dioxane 0% N/A
17 w/o catalyst & ligand 20 mol% AICI3 1,4-dioxane 0% N/A
18 w/o catalyst & ligand 20 mol% B(C6F5)3 1,4-dioxane 0% N/A
a

Unless otherwise mentioned, the reaction was run with 10 mol % rhodium complex (based on the metal) and 12 mol % ligand on a 0.1 mmol scale at 110 °C for 48 h; numbers in parenthesis are yields based on recovered starting material (brsm).

b

Isolated yield.

c

Determined by chiral HPLC.

d

Rhodium complex (5 mol%) and mixed ligands (6 mol%) were added initially; the reaction mixture was stirred at 110 °C for 24 h before another portion of the same catalyst was added.