Table 1 Optimizations of the reaction conditions.

From: Stereoselective gold(I)-catalyzed approach to the synthesis of complex α-glycosyl phosphosaccharides

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Entry

Temperature

Solvent

Additive

Yield, α/β a, b

1

20 °C

CH2Cl2

—

88%, 2.8/1

2

−78 to 0 °C

CH2Cl2

—

83%, 2/1

3c

20 °C

CH2Cl2

—

86%, 1.5/1

4

20 °C

Et2O

—

88%, 3.2/1

5

20 °C

1,4-dioxane/toluene

—

60%, 1.2/1

6

20 °C

CH2Cl2

Ph3P = O

80%, 1/1

7

20 °C

Et2O

HOTf

62%, 10/1

8

20 °C

Et2O

H+ resin

78%, 2.9/1

9

0 °C then 60 °C

ClCH2CH2Cl

—

87%, 9/1

10

0 °C then 75 °C

ClCH2CH2Cl

—

75%, 9/1

11

0 °C then 95 °C

ClCH2CH2Cl

—

0

12d

0 °C then 60 °C

ClCH2CH2Cl

—

62%, 16/1

13d, e

0 °C then 60 °C

ClCH2CH2Cl

—

85%, 9.7/1

14d, f

0 °C then 60 °C

ClCH2CH2Cl

—

57%, 20/1

  1. aReaction condition: 1a (0.05 mmol), 2a (0.075 mmol), solvent (1.0 mL), Ph3PAuNTf2 (10 mol%), 5 Å MS, 2 h. bYields of α/β mixture (α/β mixture not separable), and ratios determined by HPLC. cPh3PAuOTf was used instead. dOptimized condition: 1a (0.075 mmol) and 2a (0.05 mmol), Ph3PAuNTf2 (10 mol%), DCE (1 mL), 0 °C, 30 min, then 60 °C, 2 h. e1a (0.05 mmol) and 2a (0.05 mmol) were used instead. fReaction time was prolonged from 2 h to 3 h. Tf: trifluoromethanesulfonyl.
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