Indole → 3-(1,4-Dioxaspiro[4.5]dec-7-en-8-yl)-1H-indole

Participants

Reaction Conditions

Reaction Steps

Indole (22.6 g, 190 mmol), 1,4-cyclohexanedione monoethylene ketal (22.8 g, 145 mmol) and KOH (4.6 g, 80 mmol) were heated to reflux in 50 mL of MeOH for 6 h. The reaction mixture was cooled to 23° C., a solid precipitated and was collected by vacuum filtration. This solid was washed with 3×30 mL of H2O to give 33.3 g (130.5 mmol, a 90% yield) of the title compound as a white solid. MS (ES) m/z (relative intensity): 256 (M++H, 100).

Provenance & Evidence