Question

Devise a stepwise synthesis of the tripeptide Val-leu-Val from 3-methylbutanal$\left[{\left({\mathrm{CH}}_3\right)}_2{\mathrm{CHCH}}_2\mathrm{CHO}\right]$ as the only organic starting material. You may also use any required inorganic or organic reagents.

Short answer

Answer

Step-by-step solution

Step-by-Step SolutionStep 1: Tripeptide

There are numerous kinds of peptides. One among them is the tripeptide.Two amide bonds connect three amino acids in a tripeptide. The tripeptide lactotripeptide is prevalent in milk products.

Peptide synthesis

Larger polypeptides are synthesized by a technique termed as solid-phase technique. This technique is termed the Merrifield method. The amino acid is connected to an insoluble polymer.

The sequential incorporation of amino acids creates peptide bonds. The impurities and by-products are taken out by washing with a specific solvent.

Stepwise synthesis of Val-leu-Val from 3-methylbutanal

The generation of valine from 3-methylbutanal happens in the first step. The reaction can be given as:

Formation of valine from 3-methylbutanal

The starting material’s alpha carbon undergoes bromination. This is followed by the nucleophilic substitution of ammonia. The oxidation of the aldehyde to carboxylic acid leads to forming valine.

The next step involves the creation of leucine from the starting material reaction. The reaction of 3-methylbutanal with ${\mathrm{NH}}_4\mathrm{Cl}$and NaCN can be given as

Formation of leucine

The last step involves the condensation reaction of two valine and one leucine amino acid. This is catalyzed in the presence of small acids as:

Formation of Val-Leu-Val from two valine and leucine