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

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).

1. waitAfter a further 2 hours
2. extractionthe mixture was extracted with tert.-butyl methyl ether (2×500 mL)
3. washThe organic extracts were washed separately with saturated sodium bicarbonate solution (250 mL)
4. dry with materialThe combined organic layer was dried over anhydrous magnesium sulfate
5. filtrationfiltered
6. customevaporated under reduced pressure

ORD record

ord-a7d8abf3af0a4e3388aa583a84647a32

Source dataset

uspto-grants-2009_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07524856B2