Potassium Hydroxide → tert-butyl 3-cyclohexyl-2-phenyl-1H-indole-6-carboxylate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Methyl 3-cyclohexyl-2-phenyl-1H-indole-6-carboxylate (from Step 4) was dissolved in THF (0.2 M) and treated with aqueous KOH (2 eq., 1 M solution). The resulting mixture was heated to 80° C. for 4 h and then cooled to RT. The mixture was diluted with water and extracted with EtOAc (2×). The aqueous phase was acidified to pH 2 using hydrochloric acid (1 M) and then extracted with DCM and EtOAc. Drying over Na2SO4 and evaporation left a grey powder, which was dissolved in DCM (0.3 M). tert-Butyl N,N′-diisopropylimidocarbamate (2 eq.) was added in one portion, and the mixture stirred overnight. Another 2 eq. of the imidocarbamate were added at this point, and the heterogeneous mixture was stirred for another 24 h. Evaporation gave a white powder, which was loaded onto a column containing silica gel. Elution with PE/EtOAc (10:1) gave the title compound as an off-white solid. 1H NMR (400 MHz, CDCl3, 300K) δ 1.30-1.47 (m, 3H), 1.62 (s, 9H), 1.74-1.96 (m, 5H), 1.99-2.16 (m, 2H), 2.95 (t, J 12.4, 1H), 7.40-7.48 (m, 1H), 7.49-7.61 (m, 4H), 7.74 (d, J 8.6, 1H), 7.84 (d, J 8.6, 1H), 8.05 (s, 1H), 8.11 (bs, 1H). MS (ES+) m/z 376 (M+H)+.

Herkunft & Nachweise