Table 1 Optimization of reaction conditions between the quinoline derivative 1a and styrene 2a.

From: Visible light mediated photocatalytic [2 + 2] cycloaddition/ring-opening rearomatization cascade of electron-deficient azaarenes and vinylarenes

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Entrya

Photocatalyst (mol%)

Base

Solvent

Conversion [%]b

1

[Ir{dFCF3ppy}2(bpy)]PF6 (3a, 2)

–

CH3CN

38

2

[Ir{dFCF3ppy}2(bpy)]PF6 (3a, 2)

DBU

CH3CN

83

3

[Ru(bpy)3]Cl2·6 H2O (3b, 3)

DBU

CH3CN

n.r.

4

[Ir(ppy)3] (3c, 2)

DBU

CH3CN

80

5

4CzIPN (3d, 4)

DBU

CH3CN

43

6

[Mes-Acr]ClO4 (3e, 5)

DBU

CH3CN

n.r.

7

[Ir{dFCF3ppy}2(bpy)]PF6 (3a, 2)

DBU

THF

100 (98)c

8d

[Ir{dFCF3ppy}2(bpy)]PF6 (3a, 2)

DBU

THF

n.r.

9

–

DBU

THF

n.r.

  1. n.r. no reaction.
  2. aAll the reactions were carried our using 0.1 mmol of 1a, 0.5 mmol of 2a, 0.5 equivalents of base and 1 mL of solvent, under 455 nm (22 W m−2) LED irradiation for 17 h, unless indicated otherwise.
  3. bDetermined by 1H NMR using 1,3,5-trimetoxibencene as internal standard.
  4. cIsolated yield.
  5. dWithout light. 4CzIPN = 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobencene.
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