Triphenylphosphine → methyl 1-[1-(tert-butoxycarbonyl)piperidin-4-yl]-7-oxo-4,5,6,7-tetrahydro-1H-indole-3-carboxylate

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Reaction Steps

To a mixture of methyl 7-oxo-4,5,6,7-tetrahydro-1H-indole-3-carboxylate (100 mg 0.52 mmol), tert-butyl-4-hydroxypiperidine-1-carboxylate (105 mg, 0.52 mmol), and triphenylphosphine (136 mg, 0.52 mmol), in anhydrous THF (5 mL) at room temperature, was added di tert-butyl-diazadicarboxylate (DTAD) (120 mg, 0.52 mmol). The mixture was stirred at room temperature for 8 h. HPLC/MS suggested 40% conversion and 60% SM remained. Reagents were added, triphenylphosphine (136 mg, 0.52 mmol) and DTAD (120 mg, 0.52 mmol), the mixture was stirred for 4 hours. HPLC/MS showed 80% conversion and 20% SM remained. Reagents were re-added TPP (136 mg, 0.52 mmol) and DTAD (120 mg, 0.526 mmol) and the solution was stirred for additional 4 hours. The volatiles were removed in vacuo, the crude solid was purified by flash chromatography on silica gel (hexane/EtOAc 7/3) to afford 140 mg (70% yield) of the title compound as a white solid.

Provenance & Evidence