Table 1 Discovery and parameter evaluation of the Co-catalyzed racemic cascade reactiona,b.

From: Enantioselective Cu-catalyzed double hydroboration of alkynes to access chiral gem-diborylalkanes

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Entry

Catalyst

Ligand

Solvent

Additive

Yield (%)b

1

Co(acac)2

Xantphos

heptane

NEt3

68

2

Co(acac)3

Xantphos

heptane

NEt3

63

3

Cu(acac)2

Xantphos

heptane

NEt3

60

4

Co(acac)2

1.10-Phen

heptane

NEt3

N.D.

5

Co(acac)2

Xantphos

heptane

NHEt2

67

6

Co(acac)2

Xantphos

heptane

2,6-lutidine

66

7c

Co(acac)2

Xantphos

heptane

NEt3

70

8c

Co(acac)2

Xantphos

THF

NEt3

17

9c

Co(acac)2

Xantphos

cyclohexane

NEt3

76

10c, d

Co(acac)2

Xantphos

cyclohexane

NEt3

70

  1. aAfter Co(acac)2 (4 mol%), ligand (4 mol%), HBdan (0.24 mmol) and amine (0.2 mmol) were mixed in 0.2 mL of solvent at room temperature for 15 mins, HBpin (0.3 mmol) and 1 (0.2 mmol) were added subsequently at room temperature, then the resulting mixture was stirred at ambient temperature for 12 h, bIsolated yield, cNEt3 (0.6 mmol), dHBpin and 1 add after 8 mins.
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