Table 1 Optimization of reaction conditionsa

From: Stereoretentive cross-coupling of chiral amino acid chlorides and hydrocarbons through mechanistically controlled Ni/Ir photoredox catalysis

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Entry

Variation from standard conditions

Yieldb (%)

1

None

81 (74c)

2

1 equiv of cyclohexane

58

3

5 equiv of cyclohexane

90

4

1 equiv of 2,6-lutidine

64

5

pyridine instead of 2,6-lutidine

36

6

2,4,6-collidine instead of 2,6-lutidine

76

7

2,6-di-tert-butylpyridine instead of 2,6-lutidine

27

8

2,4,6-triphenylpyridine instead of 2,6-lutidine

53

9

Cs2CO3 instead of 2,6-lutidine

19

10

NaHCO3 instead of 2,6-lutidine

17

11

K3PO4 instead of 2,6-lutidine

20

12

No base

13

13

No light/No nickel and dtbbpy/No photocatalyst

0

  1. aReaction conditions: 1a (0.20 mmol), oxalyl chloride (1.8 equiv), DMF (cat., 0.2 μL), and CH2Cl2 (2.0 mL), 2 h. After evaporation of remaining solvent, NiCl2·glyme (5 mol %), dtbbpy (10 mol %), 2,6-lutidine (2.0 equiv), cyclohexane (3.0 equiv), Ir[dF(CF3)ppy]2(dtbbpy)PF6 (1 mol %), and benzene (8.0 mL), irradiated 12 h with a Penn PhD M2 photoreactor.
  2. bYields were determined by NMR spectroscopy using 1,1,2,2-tetrachloroethane as an internal standard.
  3. cIsolated yield, 99% ee. NPhth = phthalimidyl.
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