ChemicalBook CAS DataBase List 1R,2S-(-)-Norephedrine hydrochloride

1R,2S-(-)-Norephedrine hydrochloride synthesis

6synthesis methods

Product Name:1R,2S-(-)-Norephedrine hydrochloride
CAS Number:3198-15-0
Molecular formula:C9H14ClNO
Molecular Weight:187.67

Ethanamine, N-[(3,5-dichlorophenyl)methylene]-2,2-diethoxy-

1000210-73-0
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3198-15-0
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Yield: 99%

Reaction Conditions:

with hydrogenchloride;sodium hydroxide;LiAlH₄ in tetrahydrofuran;ethanol;water

Steps:

VIII (1R,2S)-(-)-2-amino-1-phenylpropanol.HCl
(1R,2S)-(-)-2-amino-1-phenylpropanol.HCl 5.0 g of (1R,2S)-(-)-2-amino-1-phenyl-1-(tert.butyldimethylsilyloxy)-propane (18.8 mmol) in 50 ml of dry THF were added dropwise while refluxing to a solution of 1 g of LiAlH₄ (26 mmol) in 50 ml of dry THF. After stirring for 1 hour the mixture was cooled to room temperature, and a solution of 1 ml of water in 10 ml of THF, 1 ml of 15% sodium hydroxide and 3 ml of water respectively were added dropwise. The formed salts were removed by filtration, and the filtrate was dried and evaporated. Yield 99% (crude product). This product was dissolved in 20 ml of ethanol, and 29.5 ml of 0.48 N HCl in ethanol were added. The mixture was evaporated, and 100 ml of dry ether were added to the residue. The crystalline product was filtered off. Yield 50%, [α]²⁰_D =-28° (c=1, H₂ O), melting point 144°-146° C., purity >99%.

References:

Duphar International Research B.V. US5329023, 1994, A