Methyl chloroformate → 1-Tert-butyl 4,4-dimethyl piperidine-1,4,4-tricarboxylate

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Reaction Steps

To a chilled solution of diisopropylamine (3.5 mL, 24.7 mmol) in THF (20 mL) at −78° C. was added n-BuLi (2M in hexane, 14.8 mL, 1.2 equiv.). The reaction mixture was stirred for 1 h. A solution of 1-tert-butyl 4-methyl piperidine-1,4-dicarboxylate (5 g, 20.6 mmol, 1 equiv.) in THF (15 mL) was added dropwise at −78° C. The reaction mixture was stirred for 1 h. Methyl chloroformate (1.7 mL, 22.6 mmol, 1.1 equiv.) was added to the above mixture. The reaction mixture was warmed to rt slowly while stirring. After 3 h, the reaction mixture was quenched with saturated NH4Cl and extracted with ethyl acetate. The organic layer was dried over Na2SO4 and concentrated to give 1-tert-butyl 4,4-dimethyl piperidine-1,4,4-tricarboxylate (6.2 g, quant.), which was used without further purification. LRMS (M+H+-Boc) m/z 202.1.

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