Hydrochloric Acid → HCID 67468326, compound

Participants

Reaction Conditions

Reaction Steps

To tert-butyl 3-(diethoxymethyl)-4-oxo-spiro[chromane-2,4′-piperidine]-1′-carboxylate (72 g, 160 mmol) was added hydrochloric acid (610 mL of 4.0 M, 2.5 mol). The reaction mixture was allowed to stir at 25° C. for 2 hours. Solvent was removed under vacuum, and the obtained solid was azeotroped with EtOH (3×700 mL). The resulting beige-white solid was dissolved in EtOH (685 mL) at 25° C. prior to the addition of tert-butyl N-amino-N-methyl-carbamate (29 mL, 200 mmol). The solution was allowed to stir at 25° C. overnight. To the thick beige-white slurry that formed was added hydrochloric acid (200 mL of 4.0 M, 800 mmol). The mixture was heated at 60° C. to yield a clear yellow solution. After 1 hour at 60° C., a thick white slurry developed. The slurry was allowed to slowly cool to 25° C., and solids were collected by vacuum filtration. The filter cake was rinsed with a 10% solution of EtOH in hexane (2×500 mL). The solid was placed in a vacuum oven overnight (20 mm Hg/45° C.). 1-Methyl-1H-spiro[chromeno[4,3-c]pyrazole-4,4′-piperidine]dihydrochloride (42 g, 78%) was obtained as an off-white solid. ESI-MS m/z calc. 255.3. found 256.3 (M+1)+; Retention time: 1.30 minutes (3 min run). 1H NMR (400 MHz, MeOD) δ 7.82-7.76 (m, 1H), 7.61 (s, 1H), 7.40-7.34 (s, 1H), 7.22-7.14 (m, 2H), 4.19 (s, 3H), 3.52-3.42 (m, 2H), 3.41-3.33 (m, 2H), 2.39-2.07 (m, 4H).

Provenance & Evidence