Synthesis
General procedure for the synthesis of N-Boc-5-hydroxyindole from tert-butyl 5-(benzyloxy)-1H-indole-1-carboxylate: the product of Example 93A (680 mg, 2.103 mmol) was dissolved in ethanol (20 mL) under nitrogen protection, and 10% palladium carbon (68 mg) and ammonium formate (265 mg, 4.205 mmol) were added. After stirring the reaction for 1 h at room temperature, the reaction mixture was filtered through a 0.45 μm PTFE membrane and the catalyst was washed with methanol. The filtrate was concentrated by rotary evaporator and the resulting residue was dissolved in ethyl acetate (50 mL) and washed sequentially with water (2 × 25 mL) and saturated saline (25 mL). The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated in vacuum to give N-Boc-5-hydroxyindole (475 mg, 96% yield) as a white solid.
References
[1] Patent: WO2007/76034, 2007, A2. Location in patent: Page/Page column 127
[2] Patent: WO2005/51957, 2005, A1. Location in patent: Page/Page column 57
