Triphenylphosphine → tert-Butyl 4-(4-{2-[(2-oxo-2H-chromen-7-yl)oxy]ethoxy}-1,2,5-thiadiazol-3-yl)-1-piperazinecarboxylate

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Reaction Steps

Diethyl azodicarboxylate (DEAD, 61 μl, 0.39 mmol) was added drop wise to a mixture of the product obtained in Step 2 (100 mg, 0.30 mmol), triphenylphosphine (102 mg, 0.39 mmol) and 7-hydroxycoumarin (63 mg, 0.39 mmol) in dry THF (5 mL). The reaction mixture was stirred at room temperature for 5 days. After solvent removal, the residue was purified by chromatography on silica gel eluting with hexane/EtOAc (1:1) to give the title product as a white solid (176 mg) which had low purity (67% by HPLC). This material was used directly in the following step without further purification.

Provenance & Evidence