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ChemicalBook CAS DataBase List Levodopa
59-92-7

Levodopa synthesis

9synthesis methods
Levodopa, (-)-3-(3,4-dihydroxyphenyl)-L-alanine (10.1.1), is a levorotatory isomer of dioxyphenylalanine used as a precursor of dopamine. There are a few ways of obtaining levodopa using a semisynthetic approach, which consists of the microbiological hydroxylation of L-tyrosine (10.1.1), as well as implementing a purely synthetic approach.
Oxidation of L-tyrosine, for selective introduction of a hydroxyl group at C3 of the tyrosine ring, can be accomplished in a purely synthetic manner by using a mixture of hydrogen peroxide and iron(II) sulfate mixture in water as an oxidant with permanent presence of oxygen.

The third method of levodopa synthesis consists of the acetylation of tyrosine using acetylchloride in the presence of aluminum chloride and the subsequent oxidative deacylation of the formed 3-acetyltyrosine (10.1.2) using hydrogen peroxide in sodium hydroxide solution.
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Yield:59-92-7 98.7%

Reaction Conditions:

Stage #1: (S)-2-amino-3-(3-chloro-4-hydroxyphenyl)propanoic acidwith sodium nitrate;2-Methylcyclohexanol;N-bromoacetamide at 56; for 2.16667 h;
Stage #2: with nickel dichloride at 25; for 4 h;Temperature;

Steps:

3 Example 3

A method for synthesizing a levodopa pharmaceutical intermediate comprises the following steps: A: 3 mol of 2-amino-3-(3-chloro-4-hydroxyphenyl)propionic acid was added to the reaction vessel.800ml mass fraction is 15% sodium nitrate solution, Control the solution temperature to 56 °C, Add 8mol of a 22% 2-methylcyclohexanol solution.8 mol of N-bromoacetamide was added in 4 portions over 40 min, and the reaction was continued for 90 min; B: Then continue to add 5 mol of nickel chloride powder,Control the stirring speed at 130 rpm, react for 4h, and lower the temperature to 25 °C. After standing for 50 min, the solution was layered and the oil layer was separated.Washed with a mass fraction of 26% potassium bromide solution for 40 min,Washing with a mass fraction of 35% butyl formate for 50 min, Recrystallization from a mass fraction of 66% 1-butanol solution, The anhydrous sodium sulfate dehydrating agent was dehydrated to obtain 583.317 g of levodopa, and the yield was 98.7%.

References:

CN108238965,2018,A Location in patent:Paragraph 0017; 0018; 0021; 0022; 0023-0026

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