Bromine → 5'-Bromo-1',2'-dihydrospiro[cyclohexane-1,3'-indole]-2'-one

Participants

Reaction Steps

To a solution of spiro[cyclohexane-1,3′-[3H]indol]-2′-(1′H)-one (17.6 g, 9 mmol) in acetic acid (300 mL) was added sodium acetate (8.0 g, 0.1 mol) and bromine (14.6 g, 91 mmol) with stirring. After 30 minutes at room temperature, the reaction mixture was partitioned between water and EtOAc. The aqueous phase was extracted twice with EtOAc. The combined organic layers were washed with water, dried (MgSO4) and evaporated and the residue was triturated with hexane. The precipitate was collected, and dried in vacuo to obtain 5′-bromospiro[cyclohexane-1,3′-[3H]indol]-2′(1′H)-one (16.5 g, 67%) as off-white crystals: mp 196-199° C.; 1H NMR (DMSO-d6): δ 1.62 (m, 10H), 6.8 (d, 1H, J=6.8 Hz), 7.36 (d, 1H, J=8.2, 1.8 Hz), 7.58 (dd, 1H, J=8.2, 1.8 Hz), 10.44 (s, 1H).

Provenance & Evidence