METHOD FOR PREPARING L-PHENYLEPHRINE HYDROCHLORIDE Russian patent published in 2004 - IPC

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the more effective method for preparing L-phenylephrine hydrochloride in industrial scale as compared with the known art. Prochiral N-benzyl-N-methyl-2-amino-m-hydroxyacetophenone hydrochloride is subjected at the first stage to (a) asymmetric hydrogenation using catalytic system involving [Rh(COD)Cl]₂ and chiral bidentate phosphine ligand representing (2R,4R)-4-(dicyclohexylphosphine)-2-(diphenylphosphinomethyl)-N-methylaminocarbonylpyrrolidine in the presence of a solvent; at the second stage (b) reductive debenzylation is carried out using palladium and hydrogen. As ligand, (2R,4R)-4-(dicyclohexylphosphine)-2-(diphenylphosphinomethyl)-N-methylaminocarbonylpyrrolidine immobilized on polymer can be used. Stage (a) is carried out usually in the presence of a base in the range of temperatures from 40 to 100^oC and under pressure from above 1 to 100 bars.

EFFECT: improved preparing method.

23 cl, 1 sch, 4 ex