Table 1 Optimization of reaction conditionsa

From: Mechanistic insights into excited-state palladium catalysis for C–S bond formations and dehydrogenative sulfonylation of amines

View full size image

Entry

Change in the standard reaction condition

Yield of 5 (%)

1

none

93 (88)

2

Change in Pd source: Pd(PPh3)4, Pd(PPh3)2Cl2

84, 86

PdCl2, PdI2, PdBr2

49, 54, 37

3

Change in base: Cs2CO3, Na2CO3

75, 34

K3PO4, K2HPO4

77, 21

DABCO, Quinuclidine

41, 23

4

Change in ligand: P(1-Nap)3 (20 mol%), Xantphos (10 mol%)

95, 61

rac-BINAP (10 mol%), DPEPhos (10 mol%)

89, 91

PCy3 (20 mol%)

84

5

Change in solvent: THF, PhCl, CH3CN

83, 80, 45

DMA, DME

36, 62

6

No light or Pd or ligand

0, 0, 0

7

at 100 °C (absence of light)

trace

  1. aUnless otherwise mentioned all reactions were carried out using 1-(p-tolyl)pyrrolidine (0.2 mmol), tosyl chloride (0.6 mmol), [Pd] (5 mol%), ligand (10–20 mol%), base (3 equiv), and solvent (0.1 M, 2.0 mL) by blue LEDs irradiation (34 W) with fan cooling (to keep the reaction at room temperature) for 48 h under Ar. Yields were determined by 1HNMR analysis of the crude mixture relative to trimethoxy benzene as an internal standard and isolated yield in parentheses.
Back to article page