L-Proline ethyl ester hydrochloride is the ethyl ester hydrochloride salt of L-proline, a proteinogenic cyclic amino acid featuring a pyrrolidine ring that bears the side-chain linkage to the α-carbon. The molecule contains a carboxyl group converted to an ethyl ester and an amino functionality present as a hydrochloride salt, with the stereochemistry specified as L at the α-carbon and the ring nitrogen serving as part of the proline side-chain framework. In peptide and amino acid derivative synthesis, the esterified carboxyl group and salt-form amino group support controlled handling and can be used as a precursor for preparing proline-containing peptide fragments, while the labeled salt form can aid in analytical and coupling workflows that require a defined, isolable amino acid derivative.
CAT No: CP01721
CAS No:33305-75-8
Synonyms/Alias:33305-75-8;L-prolineethylesterhydrochloride;(S)-Ethylpyrrolidine-2-carboxylatehydrochloride;EthylL-prolinateHCl;SCHEMBL133134;EthylL-prolinatehydrochloride;prolineethylesterhydrochloride;CTK6F2864;DUJGQVVONTYHLT-RGMNGODLSA-N;MolPort-006-126-678;EINECS251-449-6;ANW-42217;AKOS015900667;AM82199;L-PROLINEETHYLESTERHYDROCHLORIDE;AK117179;KB-53371;ST2414663;FT-0693350;ST51054375;K-7686;I14-5862;2(S)-pyrrolidine-carboxylicacidethylesterhydrochloride
L-Proline ethyl ester hydrochloride is the hydrochloride salt of L-proline ethyl ester, combining the pyrrolidine-containing proline backbone with an esterified carboxyl group and a stereogenic center at the alpha carbon. The salt form protonates the proline-derived amine, improving handling and enabling controlled conversion between protected/activated forms during synthesis. The ethyl ester participates in acylation and transesterification chemistry, while the secondary amine within the pyrrolidine ring supports derivatization strategies that preserve stereochemical integrity. This chiral amino acid ester functions as a practical intermediate for building peptide fragments, preparing N- and side-chain modified proline derivatives, and enabling downstream conversion to carboxylic acids or amides under standard peptide and process chemistry conditions.
1. Protected Amino Acid Chemistry
L-Proline ethyl ester hydrochloride is applied in protected amino acid synthesis where the amino acid ester and chiral center are maintained while the amine functionality is selectively managed through salt formation and subsequent derivatization. The hydrochloride counterion supports controlled handling of the esterified proline, and the ethyl ester can be carried through coupling sequences before being converted to the corresponding acid or activated derivative. N-protection strategies can be designed to enable peptide coupling compatibility while minimizing racemization at the L-stereocenter. The resulting proline-derived intermediates can be used to access N-protected proline building blocks and stereodefined fragments for peptide construction and fine chemical synthesis.
2. Peptide Synthesis
L-Proline ethyl ester hydrochloride serves in peptide synthesis workflows as a chiral proline-containing building block precursor that can be transformed into coupling-ready forms. The esterified carboxyl group allows preparation of activated intermediates for amide bond formation, while the pyrrolidine secondary amine and alpha stereochemistry support incorporation of proline into dipeptides and longer sequences. Salt-associated amine protonation can be leveraged to tune reactivity during protection/deprotection steps that align with peptide coupling chemistries. Downstream conversion to carboxylic acids or activated esters enables assembly of proline-rich peptides and proline analogs used in biochemical research and synthetic methodology development.
3. Chiral Building Block Development
L-Proline ethyl ester hydrochloride is suitable for chiral synthesis and stereodefined intermediate preparation where proline's L-configuration is required for downstream stereochemical outcomes. The chiral alpha carbon and the rigid pyrrolidine ring provide a conformationally biased scaffold that can influence the stereochemical course of subsequent derivatization at the carboxylate and ring nitrogen. Ester functionality supports iterative functional group interconversions, including hydrolysis to acids, transesterification to alternative ester types, and preparation of amide-linked derivatives. The compound can therefore be used to generate a family of chiral proline ethyl ester and proline acid derivatives for asymmetric synthesis, SAR studies, and peptidomimetic scaffold generation.
4. Side-Chain Functionalization
L-Proline ethyl ester hydrochloride is used in side-chain functionalization and amino acid derivatization strategies that target the pyrrolidine nitrogen and the ester group for subsequent conjugation or scaffold diversification. The secondary amine within the pyrrolidine ring can be selectively modified to introduce N-substituents that tune reactivity, solubility, and coupling behavior in later synthetic steps. The ethyl ester can be converted into activated acylating agents or transformed into amide and other carboxyl-derived functionalities, enabling controlled growth of molecular complexity. Resulting proline derivatives can feed into chemical biology reagent preparation, peptidomimetic construction, and intermediate generation for further functional group installation.
5. Pharmaceutical Intermediate Preparation
L-Proline ethyl ester hydrochloride supports pharmaceutical intermediate preparation where chiral proline-derived fragments are required for heterocycle formation, amide construction, and stereodefined lead optimization chemistry. The amino acid ester format enables manufacturing-friendly interconversion pathways between ester, acid, and amide forms, which can align with route design for downstream synthesis of drug-like scaffolds. The hydrochloride salt improves operational handling for scale-up and can be integrated into process chemistry sequences that require controlled amine availability. Proline-derived intermediates accessed from this compound can be employed in fine chemical synthesis programs that require stereochemically consistent building blocks for medicinal chemistry and process development.
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