Potassium Hydroxide → Benzyl 4-{2-[(di-tert-butoxyphosphoryl)oxy]ethyl}-3-oxopiperazine-1-carboxylate

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Reaction Steps

2-Bromoethyl di-tert-butyl phosphate (298 mg, 0.94 mmol) in tetrahydrofuran (1.0 ml) was added at room temperature to a stirred suspension of benzyl 3-oxopiperazine-1-carboxylate (200 mg, 0.85 mmol), powdered potassium hydroxide (57 mg, 1.0 mmol) and tetra-n-butylammonium bromide (55 mg, 0.17 mmol) in THF (2.0 ml). The reaction mixture was stirred for 90 minutes and then filtered through Celite and the filtrate evaporated to leave a colourless oil. The crude product was purified by silica gel chromatography eluting with a 2-5% mixture of methanol in dichloromethane to give benzyl 4-{2-[(di-tert-butoxyphosphoryl)oxy]ethyl}-3-oxopiperazine-1-carboxylate (220 mg, 55% yield) as a colourless oil:

Provenance & Evidence