2-tert-Butyl-1,3-diisopropylisourea → tert-butyl 3-cyclohexyl-1H-indole-6-carboxylate

Participants

Reaction Steps

2 eq of tert-butyl N,N′-diisopropylimidocarbamate (prepared according to literature precedent: Synthesis 1979, 561) were added to a solution of 3-cyclohexyl-1H-indole-6-carboxylic acid (prepared as described in published International patent application WO2004087714) in CH2Cl2 (0.4 M) and the mixture heated at reflux under N2 for 16 h. A further 2.5 eq of tert-butyl N,N′-diisopropylimidocarbamate were then added portionwise over 3 h, with heating being resumed after each addition. The reaction mixture was then filtered whilst hot through a pad of CELITE and the filtrate concentrated in vacuo. The residue was purified by flash chromatography (5% EtOAc/PE) to afford the title compound (58%); MS (ES−) m/z 298 (M−H)−.

Provenance & Evidence