L-Alanine tert-Butyl Ester Hydrochloride

Technical Specifications

Product Description & Scientific Applications

L-Alanine tert-butyl ester hydrochloride (H-Ala-OtBu·HCl) is the hydrochloride salt of L-alanine with the carboxyl group protected as the tert-butyl ester.

Phosphoramidate reagent synthesis. It condenses with phenyl phosphorodichloridate in the presence of a tertiary amine base to give phenyl (tert-butoxy-L-alaninyl)phosphorochloridate.

ProTide prodrugs. The phosphorochloridate is coupled to the 5′-hydroxyl group of a nucleoside to afford aryloxy triester phosphoramidate ProTide prodrugs. Masking the nucleoside phosphate in this way enhances membrane permeability and bypasses the rate-limiting first phosphorylation step.

Deprotection. The tert-butyl ester is removed cleanly and rapidly by 0.1 N hydrochloric acid in hexafluoroisopropanol or trifluoroethanol.

Peptide chemistry. The ester is the C-terminal residue of Z-Aib-Aib-Aib-L-Ala-OtBu, a crystallographically characterised tetrapeptide with a helical, hydrogen-bonded structure.

Quaternary amino acids. The N-protected tert-butyl ester undergoes enantioselective alkylation with a Maruoka catalyst, a key step in the synthesis of enantioenriched (S)-2-amino-3-(4-boronophenyl)-2-methylpropanoic acid, a boron carrier candidate for boron neutron capture therapy.

ACE inhibitors. The free base, liberated from the salt in situ, is tert-butyl L-alaninate. It undergoes a substitution reaction followed by treatment with hydrogen chloride to give compounds reported to show angiotensin-converting-enzyme inhibitory activity.

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