. 2017 May 23;2(5):2238–2247. doi: 10.1021/acsomega.7b00201

Table 4. Effect of Catalysts Concentration in the Synthesis of 3-Indolylquinone.

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entry	catalyst	yields^a^,^b^,^c, %
Fe₃O₄/PVP–PWA (141), g
1	0.025	60/21^c
2	0.05	82/6^c
3	0.1	94
4	0.15	94
Ag₂O, mol %
5	5	23^b
6	10	45^b
7	15	70^b
8	20	95^b
9	40	95^b

Reactions were performed with 1:1 2-methylhydroquinone/2-methylindole, 10 mL of THF, 20 mol % Ag₂O, and 3 mmol H₂O₂ at RT for 5 h; isolated yields of 3-indolylquinone after column chromatography. Bold values represent maximum product yield under optimized reaction conditions.

Fe₃O₄/PVP–PWA (141) (0.1 g).

The byproduct 2-methyl benzoquinone is formed.