Hydrochloric Acid → 4-(1H-Indol-3-YL)cyclohexanone

Participants

Reaction Conditions

Reaction Steps

To a 3-L, four-neck round bottom flask equipped with an overhead stirrer, temperature probe, addition funnel, was added 3-(1,4-dioxaspiro[4.5]decan-8-yl)-1H-indole (as prepared in the previous step, 143.2 g, 0.56 mol) and DMF (190 mL). The suspension was heated to 50° C., and aqueous HCl (2M, 290 mL) was charged to the addition funnel and added dropwise and after about 5 mins, a precipitate formed. The reaction was stirred at 30° C. for 24 h. HPLC showed there was <2% of the acetal remaining. The suspension was chilled in an ice bath to 6° C., water (1.2 L) was added, and the suspension stirred at ambient temperature for 15 mins. The solid was filtered, washed with water (250 mL), and dried in a vacuum oven at 50° C. overnight. 1H NMR (400 MHz, CHLOROFORM-d) δ: 8.16 (br. s., 1H), 7.65 (d, J=7.6 Hz, 1H), 7.35 (d, J=8.1 Hz, 1H), 7.15-7.26 (m, 1H), 7.08-7.16 (m, 1H), 6.95 (d, J=2.0 Hz, 1H), 3.33 (tt, J=3.3, 11.6 Hz, 1H), 2.28-2.66 (m, 6H), 1.88-2.06 (m, 2H).

Provenance & Evidence