Table 1 Optimization of the enantiodivergent Mannich reactiona

From: Enantiodivergence by minimal modification of an acyclic chiral secondary aminocatalyst

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Entry

Catalyst

t [h]

Yield [%]b

dr [anti/syn]c

erd

1

Ia/0.5 TfOH

10

82

>20:1

98:2

2

Ib/0.5 TfOH

10

65

7:1

39.5:60.5

3

Ic/0.5 TfOH

14

83

14:1

17:83

4

Id/0.5 TfOH

14

87

8:1

8:92

5

Ie/0.5 TfOH

14

67

5:1

14:86

6e

Id/0.5 TfOH

10

78

>20:1

3.5:96.5

7

Id

72

Trace

—

—

8

II/0.5 TfOH

48

Trace

—

—

9

III

48

Trace

—

—

10

IV

48

Trace

—

—

  1. Tf trifluoromethanesulfonyl
  2. aUnless otherwise specified, the asymmetric direct Mannich reaction of β,γ-alkynyl-α-imino ester 1a (0.1 mmol) and propylaldehyde 2a (0.3 mmol) was conducted in the presence of catalyst (20 mol %) and p-NO2-C6H4CO2H (20 mol %) in MeCN (0.8 mL) at −40 °C
  3. bYield of isolated product
  4. cDetermined by 1H-NMR or HPLC
  5. dDetermined by chiral HPLC
  6. eDichloroethane was used as the solvent
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