Hydrochloric Acid → (3S)-6,7-Dihydroxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a cold (0-5° C.) suspension of Levodopa (197.2 g, 1.0 mol) in water (1.18 L) was added 32% aqueous HCl (159.5 g, 1.4 mol). The resulting solution was cooled to 0-5° C., and 37% formaldehyde water solution (243.24 g, 3.0 mol) was added. The resulting solution was allowed to warm to 20-25° C., and stirred at 20-25° C. for 10 h. The reaction solution was cooled to 0-5° C., and 2 N aqueous NaOH (700 mL, 1.4 mol) was slowly added to adjust pH to 5-5.5. White or light yellow solids precipitated during the addition. The resulting suspension was stirred at 0-5° C. for 2-3 h. The mixture was filtered, and rinsed with water (2×500 mL). The solids were dried under vacuum to give 199.52 g of a light yellow solid. Yield=95.3%.

Provenance & Evidence