Table 1 Optimization of reaction conditions[a]

From: Cathodic oxygen reduction-enabled rhodium-catalyzed (5 + 1) C–H/O–H annulation inspired by fuel cells

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Entry

Deviation from Standard Conditions

3 Yield (%)b

1

none

84

2

nBu4NPF6 or nBu4NBF4 instead of nBu4NOAc

trace

3

CH3OH instead of CH3CN

trace

4

no Cp2Fe

56

5

Pt instead of RVC

nr

6

75 °C

65

7

65 °C

63

8

[Cp*IrCl2]2 instead of [Cp*RhCl2]2

trace

9

[(p-cymene)RuCl2]2 instead of [Cp*RhCl2]2

trace

  1. [a] Reaction conditions: 1a (0.4 mmol), 2a (0.2 mmol), [Cp*RhCl2]2 (2.5 mol%), nBu4NOAc (2.0 equiv), Cp2Fe (10 mol%), MeCN (4 mL) in undivided cell, I = 1.5 mA, 4 h. nBu = normal butyl group [b] Isolated yield.
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