Sulfuric Acid → Hydrochloric Acid

Participants

Reaction Steps

Dissolve 5-methoxy-8-chloro-11-(1-methyl-4-piperidinyl)-11H-benzo[5,6]cyclohepta[1,2-b]pyridin-11-ol (4.26 g) in CH3OH (6 mL) at 0° C. under an argon atmosphere. Add slowly a cooled solution of 92% aqueous H2SO4 (54 mL). Allow the mixture to warm to room temperature for 35 minutes. Pour the solution onto ice, basify with aqueous NaOH (25%), and extract with methylene chloride (3×). Combine the organic portions, wash with brine and dry over sodium sulfate. Filter and concentrate in vacuo. Triturate the residue with isopropyl ether to give an intermediate, 8-Chloro-6,11-dihydro-11-(1-methyl-4-piperidinyl)-5,11-epoxy-5H-benzo[5,6]-cyclohepta[1,2-b]pyridin-5-ol as a white solid (3.58 g., 92%, m.p: 170° to 174° C. as HCl salt).

Provenance & Evidence