Hydrochloric Acid → Methyl 7-methoxy-spiro[1,3-benzodioxole-2,4'-piperidine]-4-carboxylate

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Reaction Steps

A solution of 7-methoxy-1′-acetyl-spiro[1,3-benzodioxole-2,4′-piperidine]-4-carboxylic acid (143 mg, 0.467 mmol) and LiOH (224 mg, 9.34 mmol) in water (3 mL) and MeOH (3 mL) was heated to 75° C. for five hours. At room temperature the mixture was neutralized with 2M HCl and evaporated to dryness under reduced pressure. The crude 7-methoxy-spiro[1,3-benzodioxole-2,4′-piperidine]-4-carboxylic acid [LC/MS (METHOD B): (m/z) 266.2 (MH+); RT=1.57 min; purity (UV)=82%] was refluxed overnight in 1.7 M methanolic HCl (5 mL). At room temperature water (20 mL) was added. The aqueous phase was washed with Et2O (10 mL), made basic by addition of Na2CO3 and extracted with dichloromethane (3×10 mL). The organic phase was dried over MgSO4 and evaporation under reduced pressure afforded methyl 7-methoxy-spiro[1,3-benzodioxole-2,4′-piperidine]-4-carboxylate (75 mg, 57%). 1H NMR (DMSO) δ 7.31 (d, 1H), 6.72 (d, 1H), 3.87 (s, 3H), 3.78 (s, 3H), 2.96-2.77 (m, 4H), 1.94-1.83 (m, 4H).

Provenance & Evidence