Reaktion #469640

Reaktionsgleichung

3-aminobenzyl alcohol

sodium hydride

1-bromo-2-propanol

(1S)-2-(2-bromo-1-methylethoxy)tetrahydro-2H-pyran

phthalimide

→

(2S)-1-[(3-aminophenyl)methoxy]-propan-2-ol

Lösungsmittel

tetrahydrofuran

N,N-dimethylformamide

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONcontaining an O-protecting group
2. 2
   SonstigeThe tetrahydropyranyl protecting group of the resulting chiral arylmethyl ether type compound can be removed with aqueous sulfuric acid in methanol

Vorschrift

The manner in which optically active forms of arylmethoxy aliphatic amines, such as (2S)-N-methyl-1-[(3-aminophenyl)methoxy]-propan-2-amine type compounds, are provided can vary. In one approach, a 3-aminobenzyl alcohol type compound (N-protected as the phthalimide) can be alkylated with a chiral 1-bromo-2-propanol type compound containing an O-protecting group, such as (1S)-2-(2-bromo-1-methylethoxy)tetrahydro-2H-pyran using a base such as sodium hydride and a solvent such as N,N-dimethylformamide or tetrahydrofuran. The tetrahydropyranyl protecting group of the resulting chiral arylmethyl ether type compound can be removed with aqueous sulfuric acid in methanol, affording (2S)-1-[(3-aminophenyl)methoxy]-propan-2-ol. The resulting chiral alcohol intermediate can be converted to its corresponding tosylate, followed by tosylate displacement with methylamine with inversion of configuration, and finally removal of the N-phthaloyl group to give the chiral amine (2R)-N-methyl-1-[(3-aminophenyl)methoxy]-propan-2-amine. Chiral side chain compounds such as (1S)-2-(2-bromo-1-methylethoxy)tetrahydro-2H-pyran can be prepared from (2S)-1-bromo-2-propanol by treatment with 3,4-dihydro-2H-pyran in dichloromethane with p-toluenesulfonic acid as a catalyst according to the method of S. A. M. Nieuwenhuis et al., Tetrahedron 50: 13207-13230 (1994). The required (2S)-1-bromo-2-propanol can be obtained from (S)-propylene oxide (commercially available from Fluka) by treatment with hydrogen bromide in acetic acid at 0° C. The corresponding optical antipode, (2R)-N-methyl-1-[(3-aminophenyl)methoxy]-propan-2-amine can be prepared in an analogous manner from (R)-propylene oxide (commercially available from Fluka) by using the synthetic procedure of S. A. M. Nieuwenhuis et al. to prepare the tetrahydropyranyl ether of (2R)-1-bromo-2-propanol and by using the synthetic sequence described above.

Quelle