Triethylamine → Ethyl 2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate

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Reaction Steps

LCMS (Method A): m/z 367 (M+H)+ (ES+), at 1.97 min, UV inactive. tert-Butyl 2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate (0.080 g, 0.22 mmol) was stirred in DCM (10 mL) at rt and treated with 4 M HCl/dioxane (1 mL). The reaction mixture was stirred overnight at room temperature. The reaction mixture was conc. in vacuo to give a yellow solid that was used directly without further purification. The residue was dissolved in DCM (10 mL) and NEt3 (0.066 g, 0.1 mL, 0.66 mmol) and ethyl chloroformate (0.036 g, 0.03 mL, 0.32 mmol) were added and the reaction mixture was stirred at rt overnight under nitrogen. The solvents were removed in vacuo, and the residue was partitioned between DCM and sat. NaHCO3 sol., organic layer washed with sat. NaCl sol. and dried over MgSO4. The residue was purified by column chromatography (normal phase, [Biotage SNAP cartridge KP-sil 10 g, 40-63 μm, 60 A, 12 mL per min, gradient 0% to 8% MeOH in DCM]) to give ethyl 2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate (0.069 g, 93%) as an amber oil.

Provenance & Evidence