H-His(1-Trt)-OMe · HCl

H-His(1-Trt)-OMe · HCl is a histidine-derived amino acid methyl ester hydrochloride bearing a trityl (Trt) protecting group on the imidazole N1 position, with the α-amino group present as a free amine (H) and the α-carboxyl functionality masked as a methyl ester (OMe) under salt form. The stereogenic α-carbon of histidine is retained from the chiral starting material, and the imidazole ring remains chemically addressable at the N3 position while the N1 site is protected to control regioselective reactivity during peptide coupling and side-chain functionalization. The hydrochloride counterion improves handling of the ester hydrochloride and can support controlled deprotection and coupling workflows where N1 protection prevents undesired imidazole participation. The combination of an N-protected imidazole and an ester-activated carboxyl group makes the compound a practical chiral intermediate for protected amino acid synthesis, peptide building block preparation, and downstream conversion to carboxylic acid or activated derivatives.

1. Peptide Synthesis

H-His(1-Trt)-OMe · HCl is used in peptide synthesis workflows as an imidazole-N1 protected histidine methyl ester, enabling controlled Nα coupling while minimizing side reactions from the imidazole during amide bond formation. The Trt group suppresses imidazole nucleophilicity at N1, while the remaining imidazole functionality can be preserved for later on-resin or solution-stage transformations after ester hydrolysis and/or ester-to-acid activation. The methyl ester handle supports C-terminal installation strategies where ester deprotection or conversion to carboxylate derivatives can be integrated into protected amino acid chemistry. The hydrochloride salt form can facilitate consistent handling of the amino acid building block in automated or semi-automated peptide assembly, supporting generation of histidine-containing peptide segments for research-grade libraries and process-scale intermediate preparation.

2. Side-Chain Functionalization

H-His(1-Trt)-OMe · HCl is applied in side-chain functionalization and chemical biology reagent construction where histidine's imidazole chemistry is leveraged after selective protection management. The N1-Trt protection pattern enables regioselective control over imidazole reactivity, allowing subsequent derivatization at the remaining imidazole positions once Trt is removed under compatible conditions. The methyl ester can be converted to a carboxylic acid or activated acid to facilitate conjugation to linkers, scaffolds, or solid supports while maintaining the imidazole as a chemically defined motif. The resulting histidine derivatives can serve as intermediates for peptidomimetic construction, metal-binding probes, and enzyme-interaction studies that require a defined imidazole environment.

3. Protected Amino Acid Chemistry

H-His(1-Trt)-OMe · HCl functions as a protected amino acid intermediate for manufacturing routes that require orthogonal protection of the histidine side chain during stepwise synthesis. The imidazole N1-Trt group provides orthogonality relative to common peptide coupling conditions, while the methyl ester offers a protected C-terminal equivalent that can be carried through coupling and then converted to an acid for further transformations. The hydrochloride salt supports reproducible material handling and can be incorporated into process chemistry intermediate stages where salt formation improves crystallization or feed preparation. The compound's defined stereochemistry and protection scheme make it suitable for preparing larger protected amino acid sets used in fine chemical synthesis, including histidine-containing building blocks for peptide analog manufacturing and amino acid derivative libraries.

4. Bioconjugation Chemistry

H-His(1-Trt)-OMe · HCl is used as a precursor for bioconjugation reagents where histidine's imidazole can be presented in a controlled chemical context after deprotection and functional group conversion. The N1-Trt protection limits premature imidazole involvement during linker attachment strategies, while the ester functionality enables transformation into carboxylate or activated carboxyl derivatives for amide or ester coupling to biomolecule-compatible handles. The compound's amino acid backbone supports incorporation into peptide-like conjugates, including short histidine-containing linkers used for biomolecule labeling and affinity capture designs. Downstream derivatives generated from this intermediate can be used to prepare defined conjugation scaffolds for chemical biology studies and applied research materials where imidazole positioning affects molecular recognition.

5. Analytical Reference Standards

H-His(1-Trt)-OMe · HCl is suitable for analytical research and method development as a structurally defined histidine derivative with clear protection and ester features that can be monitored by chromatographic and spectrometric techniques. The Trt-protected imidazole N1 and methyl ester provide characteristic mass and fragmentation patterns that support identification of protected amino acid intermediates, peptide building blocks, and deprotection progress in synthetic workflows. The hydrochloride salt form can be used to generate consistent reference material for stability checks, impurity profiling, and verification of protection-group integrity during peptide synthesis and downstream processing. Analytical standards derived from this compound can support quality-by-design documentation for amino acid derivative manufacturing and provide traceable benchmarks for process chemistry intermediate characterization.

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