Water → tert-Butyl 1-oxa-6-azaspiro(2.5)octane-6-carboxylate

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Reaction Steps

Potassium tert.-butoxide (31 g) was added to a stirred suspension of trimethylsulfoxonium iodide (60.8 g) in 1,2-dimethoxyethane (250 mL) at 20° C. After 1 hour, the mixture was added portionwise over 30 minutes to a stirred solution of 4-oxo-1-piperidinecarboxylic acid, 1,1-dimethylethyl ester (50 g) in 1,2-dimethoxyethane (50 mL) at 0° C. After a further 2 hours, water (500 mL) was added and the mixture was extracted with tert.-butyl methyl ether (2×500 mL). The organic extracts were washed separately with saturated sodium bicarbonate solution (250 mL). The combined organic layer was dried over anhydrous magnesium sulfate, filtered and evaporated under reduced pressure. The residual oil was co-evaporated with toluene (100 mL) to give the sub-title compound (43.25g) as a solid. 1H-NMR (CDCl3, 400 MHz): δ 3.75-3.70 (m, 2H); 3.47-3.38 (m, 2H); 2.69 (s, 2H); 1.84-1.75 (m, 2H); 1.48-1.43 (m, 2H); 1.46 (s, 9H).

Provenance & Evidence