Table 1 Optimization of the reaction conditionsaView full size image

From: Sulfonamide-directed site-selective functionalization of unactivated C(sp3)−H enabled by photocatalytic sequential electron/proton transfer

Entry

Variation from the standard conditions

Yield (%)b

1

None

62

2

PC-1 (3 mol%)

67

3

Co(dmgH)2PyCl (8 mol%)

64

4

PC-2 instead of PC-1

55

5

PC-3, PC-4 or PC-5 instead of PC-1

14, trace, 23

6

NaOAc, Cs2CO3 or K3PO4 instead of TFA

n.r.

7

ACN: HFIP = 3:1

86

8

HFIP or DMSO instead of ACN

n.r.

9

DCM or DCE instead of ACN

51, 56

10

Without PC-1, [Co], TFA or light irradiation

n.r.

11

O2 instead of Co(dmgH)2PyCl

trace

12

PG2 or PG9 instead of PG1

75, 53

13

PG3,4,5 or PG12 instead of PG1

<5c

14

PG6,7,8, PG10 or PG11 instead of PG1

n.r.

  1. ACN acetonitrile, TFA trifluoroacetic acid, HFIP 1,1,1,3,3,3-hexafluoro-2-propanol, DMSO dimethyl sulfoxide, DCM dichloromethane, DCE 1,2-dichloroethane, n.r. no reaction.
  2. aStandard conditions: 1a (0.2 mmol), 2a (0.4 mmol), PC-1 (2 mol%), Co(dmgH)2PyCl (5 mol%), TFA (0.4 mmol), ACN (2.0 mL, 0.1 M), 2 × 25 W blue LEDs, room temperature, under a nitrogen atmosphere, 24 h.
  3. bIsolated yield.
  4. cYields were determined by analysis of the 1H NMR spectra of the reaction mixture using 3,4,5-trichloropyridine as an internal standard.
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