Table 1 Optimization study of asymmetric N-oxidation

From: Asymmetric N-oxidation catalyzed by bisguanidinium dinuclear oxodiperoxomolybdosulfate

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Entry

Catalyst

Oxometallate

Additive

yield (%)a,b

erc

1

BG1

Na2MoO4

NaHSO4

68

57.5:42.5

2

BG1

Ag2MoO4

NaHSO4

90

64:36

3

BG1

Ag2MoO4

KHSO4

99

65:35

4

BG2

Ag2MoO4

KHSO4

91

81.5:18.5

5d

BG2

Ag2MoO4

KHSO4

87

85:15

6d

BG3

Ag2MoO4

KHSO4

22

75:25

7d

BG4

Ag2MoO4

KHSO4

70

86:14

8d

BG5

Ag2MoO4

KHSO4

82

87:13

9d,e

BG5

Ag2MoO4

KHSO4

98

93.5:6.5

  1. aReaction condition: 1a (0.05 mmol), catalyst (2 mol%), oxometallate (2 mol%), additive (0.5 equiv.) and H2O2 (1.2 equiv.) in 1.0 mL iPr2O at 0 °C for 36 hours, bIsolated yield, cDetermined by HPLC analysis on a chiral stationary phase, d0.3 equiv. KHSO4 and 25% H2O2 were used, e8 mol% BG5 and 4 mol% Ag2MoO4 were used. BG: bisguanidinium.
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