To an ice cold solution of methyl 2-isocyanatobenzoate (0.18 g, 1.0 mmol) in dichloromethane (3 mL) was added dropwise a solution of 1-tert-butylpiperazine dihydrobromide (0.28 g, 0.92 mmol) and N,N-diisopropylethylamine (0.36 mL, 2.1 mmol) in N,N-dimethylformamide (5 mL). The reaction solution was stirred at room temperature for 1 h, diluted with ethyl acetate, washed with saturated aqueous sodium bicarbonate, dried over magnesium sulfate, filtered, and concentrated in vacuo to give 0.28 g (95%) of a yellow oil.
