Carbamic acid, (tetrahydro-4-oxo-2H-pyran-3-yl)-, 1,1-dimethylethyl ester (9CI) synthesis

Yield:1316831-46-5 44%

Reaction Conditions:

with ammonium acetate;sodium cyanoborohydride in methanol at 20; for 48 h;

Steps:

(4-Amino-tetrahydro-pyran-3-yl)-carbamic acid tert-butyl ester (mixture of diastereomers)

(4-Amino-tetrahydro-pyran-3-yl)-carbamic acid tert-butyl ester (mixture of diastereomers) (4-Oxo-tetrahydro-pyran-3-yl)-carbamic acid tert-butyl ester (CAS 477584-38-6, 446 mg, 2.07 mmol) was dissolved in 20 mL methanol. Ammonium acetate (1.63 g, 21 mmol) and sodium cyanoborohydride (507 mg, 8.1 mmol) were added and the reaction mixture was stirred at room temperature for 2 days. Ethyl acetate and 2N sodium carbonate solution were added. The organic layer was separated and the aqueous layer was extracted three times with ethyl acetate. The combined extracts were dried over sodium sulfate, filtered and concentrated in vacuo. The residue was purified with flash column chromatography on silica eluting with a gradient (dichloromethane/methanol/ammonia 100:0:0->140:10:1) to provide 199 mg (44%) of the title compound as a white solid. MS (m/e): 161.2 (M-butene)⁺.

References:

US2011/190349,2011,A1 Location in patent:Page/Page column 18