Table 1 Investigation of the reaction conditions

From: Late-stage O-sulfation with a bioinspired sulfuryl donor

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Entry

Variation from standard conditionsa

Yield of 1 (%)b

1

None

72

2

without Mn(OTf)2

trace

3

MnCl2 as cat.

45

4

Fe(OTf)3 as cat.

51

5

AgOTf as cat.

trace

6

DCM as solvent

76

7

Argon atmosphere

77

8

50 °C

68

9

K-PNPS instead of nBu4N-PNPS

48c

10

Na-PNPS instead of nBu4N-PNPS

48c

11

Et4N-PNPS instead of nBu4N-PNPS

55c

  1. aStandard conditions: O-sulfation was performed with testosterone 1a (0.1 mmol, 1.0 equiv), tetrabutylammonium p-nitrophenyl sulfate (nBu4N-PNPS, 1.5 equiv), and Mn(OTf)2 (0.01 mmol, 10 mol%) in MeCN (0.5 mL) at 25 °C for 4 h.
  2. bNMR yields.
  3. cSulfated product was obtained with the corresponding counterion.
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