Dimethyl Sulfoxide → Tert-butyl 4-((4-(methoxycarbonyl)oxazol-2-yl)methyl)piperazine-1-carboxylate

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Reaction Steps

A dimethyl sulfoxide (10 mL) solution of tert-butyl-1-piperazine carboxylate (1.06 g, 5.70 mmol) and N,N-diisopropylethylamine (2.98 mL, 17.1 mmol) was treated at room temperature with methyl (2-chloromethyl)oxazole-4-carboxylate (1.0 g, 5.70 mmol; portion-wise addition) and stirred overnight. The mixture was diluted with ethyl acetate and washed with saturated aqueous sodium chloride. The organic layer was dried on magnesium sulfate, filtered and concentrated to give the intermediate tert-butyl 4-((4-(methoxycarbonyl)oxazol-2-yl)methyl)piperazine-1-carboxylate (MS (ESI) m/z 325.7 [M+H]+. The intermediate was dissolved in dichloromethane (15 mL) at room temperature and treated with trifluoroacetic acid (5 mL) dropwise. The mixture was stirred for 4 hours and was then concentrated under vacuum to give the title compound (1.60 g). MS (ESI) m/z 226.1 [M+H]+.

Provenance & Evidence