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

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Reaction Steps

tert-Butyl 2-[(methylsulfonyl)oxy]-6-azaspiro[3.4]octane-6-carboxylate isomer 1 (1.79 g, 5.73 mmol) and ethyl isonipecotate (4.49 g, 28.62 mmol) were heated together to 65° C. for 5 days. The reaction mixture was reduced in volume in vacuo, and the residue was purified by column chromatography (normal phase, [Biotage SNAP cartridge KP-sil 100 g, 40-63 μm, 60 A, 50 mL per min, gradient 1% to 4.5% MeOH in DCM]) to give tert-butyl 2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate (0.264 g, 12.5%) as a yellow oil.

Provenance & Evidence