Water → Tert-butyl 3'-(hydroxymethylene)-4'-oxo-3',4'-dihydrospiro-[piperidine-4,2'-pyrano[3,2-b]pyridine]-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To a suspension of sodium methoxide (594 mg, 11.0 mmol) in THF (5 mL) was added a suspension of tert-butyl 4′-oxo-3′,4′-dihydrospiro[piperidine-4,2′-pyrano[3,2-b]pyridine]-1-carboxylate (1.0 g, 3.1 mmol) in THF (10 mL), followed by ethyl formate (2.5 mL, 31 mmol) and the reaction mixture was stirred at 25° C. for 3 hours. Additional sodium methoxide (170 mg, 3.1 mmol) and ethyl formate (0.25 mL, 3.1 mmol) were added and the reaction mixture was stirred at 25° C. for 1 hour. The reaction mixture was poured into water and was extracted with ethyl acetate (4×). The aqueous layer was saturated with solid NaCl and was extracted with ethyl acetate (5×). The organic layers were combined and dried over sodium sulfate. The precipitate formed was filtered and washed with ether (2×). The solid product was dissolved in hot dichloromethane/MeOH (1:1) and filtered, and the filter cake was rinsed with additional hot dichloromethane/MeOH (1:1) (4×) to dissolve all product and remove solid sodium sulfate. The combined filtrates were evaporated to afford tert-butyl 3′-(hydroxymethylene)-4′-oxo-3′,4′-dihydrospiro-[piperidine-4,2′-pyrano[3,2-b]pyridine]-1-carboxylate (560 mg, 52%) as a yellow solid. ESI-MS m/z calc. 346.2. found 347.5 (M+1)+; Retention time: 0.98 minutes (3 min run).

Provenance & Evidence