The Synthetic Routes of L-Valine (2R,3R,11bR)-1,3,4,6,7,11b-hexahydro-9,10-dimethoxy-3-(2-methylpropyl)-2H-benzo[a]quinolizin-2-yl ester

L-Valine is an essential amino acid that is widely used in the pharmaceutical, cosmetic, and food industries.
One of the most commonly used methods to synthesize L-Valine is through chemical routes.
One such route is the synthesis of (2R,3R,11bR)-1,3,4,6,7,11b-hexahydro-9,10-dimethoxy-3-(2-methylpropyl)-2H-benzo[a]quinolizin-2-yl ester, a synthetic analogue of L-Valine.

The synthesis of this compound involves several chemical steps, starting with the synthesis of the precursor molecule, 3-nitro-2-butanone.
This molecule is then reduced to 2-butanone using hydrogen in the presence of a metal catalyst, such as palladium.
The 2-butanone is thenomerized to 2,3-butanediol using a basic catalyst, such as sodium hydroxide.

The 2,3-butanediol is then reduced to 2,3-butanol using hydrogen in the presence of a metal catalyst, such as palladium.
The 2,3-butanol is then treated with bromine to form 2,3-butyl bromide.
This compound is then reacted with sodium hydroxide to form the corresponding sodium salt, which is then treated with phenyl Grignard reagent to form the phenylthio analogue.

The phenylthio analogue is then treated with bromine to form the bromide salt.
This salt is then treated with a metal catalyst, such as ruthenium or osmium, to form the corresponding alkene.
This alkene is then treated with a halogen, such as chlorine or bromine, to form the corresponding halide.

The halide is then reduced to the corresponding alkyne using hydrogen in the presence of a metal catalyst, such as palladium.
The alkyne is then treated with ammonia to form the corresponding amide.
This amide is then treated with a base, such as sodium hydroxide or potassium hydroxide, to form the corresponding carboxylic acid.

The carboxylic acid is then treated with a base, such as sodium hydroxide, to form the corresponding sodium salt.
This sodium salt is then treated with a basic reagent, such as 2,6-lutidine or pyridine, to form the corresponding amide.
The amide is then treated with a strong acid, such as hydrochloric acid or sulfuric acid, to form the corresponding acid halide.

The acid halide is then treated with a base, such as sodium hydroxide or potassium hydroxide, to form the corresponding sodium or potassium salt.
This salt is then treated with a thiol reagent, such as dithiothreitol or cysteine, to form the corresponding thiol.

The thiol is then treated with a reducing agent, such as hydride or borohydride, to form the corresponding thiol alcohol.
This thiol alcohol is then treated with a strong acid, such as hydrochloric acid or sulfuric acid, to form the corresponding acid.

The acid is then treated with a base, such as sodium hydroxide or potassium hydroxide, to form the corresponding sodium or potassium salt.
This salt is then treated with a metal catalyst, such as ruthenium or osmium, to form the corresponding alkene.
This alkene is then treated with a halogen, such as chlorine or bromine, to form the corresponding halide.

The final step in the synthesis of (2R,3R,11bR)-1,3,4,6,7,11b-hexahydro-9,10-dimethoxy-3-(2-methylpropyl)-2H