Dimethylformamide → 6-tert-Butyl indole-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

(5-tert-Butyl-2-methyl-phenyl)-carbamic acid tert-butyl ester (prepared in Example CC; 19.7 g, 75 mmol) in 100 mL of THF was cooled to −40° C. To it was added tert-butyllithium (1.5 M, 100 mL, 150 mmol), dropwise with stirring, at −45° C. to −35° C. After the addition was complete, the reaction was stirred at −35° C. for another 15 minutes. DMF (10.97 g, 150 mmol) was added dropwise, and the reaction mixture was stirred at −35° C. for 30 minutes, followed by slow warming to room temperature. The reaction was quenched with saturated NH4Cl solution and diluted with EtOAc. The organic layer was washed with brine, dried (MgSO4), and concentrated. The residue was dissolved in 100 mL of THF and 2 mL of concentrated HCl and stirred at room temperature for 1 hour. EtOAc was added, and the solution was washed with saturated NaHCO3 solution and brine and dried (MgSO4). Concentration gave a residue that was purified by flash silica gel chromatography (5%-50% EtOAc in hexanes). MS(APCI): 274 (M+H).

Provenance & Evidence