3-Methyl-2-butanone → 5-Methoxy-2,3,3-trimethyl-3H-indole

Participants

Reaction Steps

A mixture of 0.18 mole of 4-methoxy-phenylhydrazine, 0.27 mole of methyl isopropylketone, 5 drops of acetic acid and 300 ml of ethanol was refluxed for 3 h, whereupon the solvent was evaporated. The dark residue (28 g of hydrazone) was dissolved in 125 ml of ethanol. After adding 54 ml of a 15% by weight solution of concentrated sulphuric acid in ethanol the mixture was refluxed for 2.5 h. The white precipitate (ammonium sulphate) was filtered and the filtrate was diluted with 750 ml of water, neutralized with a few ml of aqueous 5N sodium hydroxide and extracted with ether. The dried extract was distilled in vacuo. Boiling point: 138°-142° C/8 mm Hg.

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