H-D-Pro-OtBu (syrup) is a protected, esterified proline derivative in which the amino group is in the N-acetylated (H-D-) form and the carboxyl group is converted to a tert-butyl ester, giving a proline-based cyclic amino acid framework with a pyrrolidine ring. The molecule contains a free secondary amine functionality consistent with a deprotected amino terminus (as indicated by "H-" in the name), while the tert-butyl ester masks the carboxylic acid as an alkoxycarbonyl group that can be removed under conditions that deprotect tert-butyl esters, restoring the carboxylate for subsequent coupling chemistry. As a peptide-synthesis or amino acid intermediate, it is employed to control chemoselectivity during stepwise formation of amide bonds and to provide a stable, ester-protected proline building block for preparing more complex proline-containing peptides or peptide analogues.
CAT No: CP27573
CAS No:90071-62-8
Synonyms/Alias:H-D-PRO-OTBU;90071-62-8;(R)-tert-Butylpyrrolidine-2-carboxylate;D-Prolinet-butylester;H-D-Pro-OtBu(syrup);D-prolinetert-butylester;tert-butyl(2R)-pyrrolidine-2-carboxylate;tert-butylD-prolinate;AC1OC3EA;SCHEMBL248747;1,1-dimethylethylD-prolinate;CTK7F3310;MolPort-014-931-258;XJJBXZIKXFOMLP-SSDOTTSWSA-N;ZINC156852;ANW-43229;KM2898;AKOS016842763;AJ-13892;AK-91730;KB-296988;FT-0699179;ST24026471;(R)-Pyrrolidine-2-carboxylicacidtert-butylester
H-D-Pro-OtBu (syrup) is a chiral, protected proline derivative in which the amino function is present as an N-protected form (H-D-Pro-) and the carboxyl group is masked as a tert-butyl ester (OtBu), yielding a stable amino acid ester suitable for peptide chemistry. The D-configuration at the proline stereocenter provides defined stereochemical control for incorporating a D-amino acid residue into peptide frameworks and for generating stereochemically consistent research intermediates. The proline ring constrains the backbone conformation and influences coupling behavior and downstream cyclization or ring-locked conformational effects in peptidomimetic designs. The tert-butyl ester can be selectively deprotected under acid-labile conditions to reveal a free carboxylic acid for subsequent amide bond formation or for conversion into other carboxyl-activated intermediates.
1. Peptide Synthesis
H-D-Pro-OtBu (syrup) is applied in peptide building workflows where a D-proline residue is required with a protected carboxyl group to control chemoselectivity during coupling. The N-protected proline framework and the tert-butyl ester enable stepwise peptide assembly by allowing selective activation of the carboxyl functionality after deprotection, while the ester protection helps prevent premature side reactions. The rigid cyclic side chain supports incorporation into constrained peptides and can be used to tune backbone dihedral preferences in peptide analogs. Downstream, deprotected carboxylates can participate in amide coupling to generate D-proline-containing peptide segments for research-grade peptide libraries and sequence-defined constructs.
2. Protected Amino Acid Chemistry
H-D-Pro-OtBu (syrup) serves as a chiral amino acid ester intermediate for protected amino acid synthesis and for constructing stereochemically defined reagents from D-proline. The tert-butyl ester provides an acid-labile protecting-group handle that can be removed to access carboxylic acid functionality for further derivatization, including conversion to acyl chlorides, mixed anhydrides, or coupling-ready activated species. The D-stereochemistry supports stereospecific downstream transformations and helps maintain configuration integrity through multi-step synthesis sequences. The resulting carboxyl-derived intermediates can be used to prepare additional protected derivatives, enabling controlled assembly of peptide building blocks and process-compatible intermediate streams.
3. Peptidomimetics And SAR Studies
H-D-Pro-OtBu (syrup) is suitable for peptidomimetic construction in structure-activity relationship studies where D-amino acid incorporation is used to modulate conformational stability and proteolytic resistance patterns in peptide-like scaffolds. The proline ring and its stereodefined D-configuration can be leveraged to produce constrained analogs that probe how backbone geometry influences binding-site recognition and functional behavior in vitro assays. The protected ester form supports sequential functional-group management, including late-stage carboxyl deprotection for coupling to diverse side-chain-bearing fragments. Generated D-proline-containing analogs can then be advanced into SAR-focused molecular series, supporting systematic variation of stereochemistry and backbone constraints within peptide-mimetic libraries.
4. Chemical Manufacturing Intermediates
H-D-Pro-OtBu (syrup) is employed as a manufacturing-oriented chiral intermediate for fine chemical synthesis routes that require a protected D-proline ester with controlled functional-group protection. The tert-butyl ester protection strategy supports storage and handling stability while enabling predictable deprotection to a carboxylic acid for downstream acylation steps in batch or continuous synthesis planning. The cyclic proline structure can reduce variability in stereochemical outcomes when preparing D-amino acid derivatives used in peptide-manufacturing pipelines and specialty chemical production. Carboxylic acid liberation from the ester under acid-labile conditions enables integration into standardized coupling sequences, supporting scalable preparation of D-proline-containing building blocks and related acyl intermediates.
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