A 0° C. suspension of 5-carbomethoxy-1,2-dihydro-9H-carbazol-4(3H)-one (1.0 g, 4.11 mmol), a catalytic amount of NaI (ca. 10 mg) and K2CO3 (1.1 g, 8.22 mmol) in 10 mL of DMF was treated with cyclohexylmethyl bromide (0.631 mL, 4.52 mmol). After stirring overnight at ambient temperature, an additional 0.63 mL cyclohexylmethylbromide was added, and the resulting mixture was heated at 60° C. for 3 hours. The mixture was poured into H2O (30 mL) and extracted with EtOAc (2×25 mL). The combined organic layers were washed with H2O (4×50 mL), dried over anhydrous Na2SO4, filtered and concentrated in vacuo. The residue was purified by radial chromatography on silica gel (elution with a gradient of 20% to 40% EtOAc/hexanes) to afford 1.36 g (4.01 mmol; 97%) of 9-[(cyclohexyl)methyl]-5-carbomethoxy-1,2-dihydrocarbazol-4(3H)-one as a white foam. IR (CHCl3, cm−1) 3011, 2932, 2857, 1725, 1649, 1469, 1446, 1288 and 1120. MS (ES) m/e 340 (M+1), 453 (M+AcO−). FAB HRMS m/e, Calcd for C21H26NO3: 340.1913. Found: 340.1916 (M+1).
