Potassium Hydroxide → 5-Nitro-3-(1,4-dioxaspiro[4.5]dec-7-en-8-yl)-1H-indole

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Reaction Steps

A solution of 5-nitroindole (38) (3.0 g, 18.501 mmol) in dry methanol (50 mL) was treated with KOH (5.6 g) at room temperature. After stirring for 10 min., 1,4-cyclohexanedione monoethylene ketal (7.22 g, 46.253 mmol) was added and the resulting solution was refluxed for 36 h. The reaction was brought to room temperature and solvent was evaporated. Crude was diluted with water (50 mL), precipitated solid was filtered off and washed with water (2 10 mL). The precipitate was dried under vacuum to obtain compound 78 (4.7 g, 85%) as a solid. For spectral data, please see Example 23.

Provenance & Evidence