Cesium carbonate → Tert-butyl 2-phenylsulfonyl-4,5-dimethyl-5,6,7,8,9,10-hexahydro-7,10-epiminocyclohepta[b]indole-carboxylate

Participants

Reaction Steps

A mixture of the product of step C (230 mg, 0.57 mmol), sodium benzenesulfinate (112 mg, 0.68 mmol), di-palladium-tris(dibenzylideneacetone) (52 mg, 0.057 mmol), cesium carbonate (277 mg, 0.85 mmol), xantphos (66 mg, 0.11 mmol) and tetrabutyl ammonium chloride (189 mg, 0.68 mmol) was taken up in toluene (3.2 mL). The reaction flask was purged with nitrogen and heated at reflux for 4 h under a nitrogen atmosphere. After cooling to ambient temperature the reaction mixture was filtered through a celite pad and the resulting filtrate concentrated in vacuo. The crude product was purified by flash column chromatography (SiO2, 7.5:2.5 hexanes/ethyl acetate) to give tert-butyl 2-phenylsulfonyl-4,5-dimethyl-5,6,7,8,9,10-hexahydro-7,10-epiminocyclohepta[b]indole-carboxylate (110 mg, 41%) as an off-white solid: 1H NMR (CDCl3, 300 MHz): δ 8.02 (br s, 1H), 7.93-7.96 (m, 2H), 7.40-7.52 (m, 3H), 7.34 (br s, 1H), 5.13-5.33 (m, 1H), 4.53-4.80 (m, 1H), 3.83 (s, 3H), 3.14-3.47 (m, 1H), 2.74 (s, 3H), 2.45 (d, J=15.9 Hz, 1H), 2.10-2.38 (m, 2H), 1.86-1.98 (m, 1H), 1.58-1.67 (m, 1H), 1.37 (br s, 9H).

Provenance & Evidence