Ac-DL-Phe-ONp is an N-acetylated, racemic (DL) phenylalanine derivative in which the carboxyl group is converted to an ONp ester (p-nitrophenyl ester), yielding a phenylalanine-based amino acid carboxylate with a protected amino functionality. The molecule contains an acetamide (Ac-NH-) replacing the free α-amino group, while the ONp ester bears a p-nitrophenoxy leaving group that can undergo nucleophilic acyl substitution under appropriate conditions, and the side chain remains the benzyl group characteristic of phenylalanine. Ac-DL-Phe-ONp is used as an activated amino acid derivative for peptide coupling and for preparing phenylalanine-containing amide bonds in solution-phase synthesis and related chemical biology workflows where controlled acyl transfer from an ONp ester is required.
CAT No: CP27075
CAS No:38806-34-7
Synonyms/Alias:AC-DL-PHE-ONP;38806-34-7;N-Acetyl-dl-phenylalaninep-nitrophenylester;Acetyl-DL-phenylalanine4-nitrophenylester;4-NITROPHENYL2-ACETAMIDO-3-PHENYLPROPANOATE;NSC408370;AC1L8AAY;A4376_SIGMA;SCHEMBL7315204;CTK8F7532;OBFGGGOSBTXXCS-UHFFFAOYSA-N;EINECS254-131-5;NSC-408370;AM015719;OR067969;OR265751;4-NitrophenylN-acetyl-3-phenyl-DL-alaninate;(4-nitrophenyl)2-acetamido-3-phenylpropanoate;DL-Phenylalanine,N-acetyl-,4-nitrophenylester;4-Nitrophenyl2-(acetylamino)-3-phenylpropanoate#;14009-94-0
Ac-DL-Phe-ONp is an N-acetylated DL-phenylalanine derivative bearing an active ester (ONp, p-nitrophenyl ester) at the carboxylate position, which makes it a practical electrophilic amino acid building block for acyl transfer and peptide-related coupling workflows. Because the stereocenter at the α-carbon is racemic (DL), this reagent is commonly selected when stereochemical uniformity is not required, such as in method development, standard preparation, or preparative synthesis of acylated intermediates. The p-nitrophenyl ester leaving group enables efficient downstream formation of amide bonds under appropriate conditions, and the N-acetyl cap provides a defined, non-free amino terminus for controlled reactivity.
1. Amide Coupling Building Block
Ac-DL-Phe-ONp is used as an activated amino acid derivative for forming amide linkages in peptide chemistry and in the preparation of acylated intermediates where a defined N-acetylated phenylalanine motif is required. Researchers in peptide synthesis and medicinal chemistry frequently employ ONp esters to drive coupling to amine-containing partners, enabling rapid access to N-acetyl phenylalanine amide products used as reference compounds, substrate analogs, or synthetic intermediates. The presence of the p-nitrophenyl ester supports straightforward activation chemistry, while the N-acetyl group helps standardize the amino terminus so the coupling step focuses on the carboxyl-to-amine bond formation.
2. Peptide Fragment Intermediate Synthesis
Ac-DL-Phe-ONp serves as a convenient electrophilic fragment for assembling short peptide segments or peptide-like structures in solution-phase workflows, particularly when the target sequence begins with an N-acetylated phenylalanine residue. Peptide and peptidomimetic developers use this reagent to introduce the acylated phenylalanine unit into amide-linked constructs without requiring a separate activation step from the free acid. In synthetic planning, the ONp ester functionality is valued for its reactivity toward nucleophilic amines, allowing efficient condensation to generate dipeptide and higher-order peptide intermediates that can be carried forward into further functionalization or purification steps.
3. Analytical Standard and Reference Preparation
Ac-DL-Phe-ONp is also used in analytical chemistry contexts where activated phenylalanine derivatives are needed to prepare standards, calibration-related materials, or model compounds for method development. Laboratories developing LC-MS or derivatization-based workflows may use this reagent to generate well-defined amide derivatives that reflect the reactivity of activated carboxylates, supporting reproducible performance checks and comparative studies across sample sets. The N-acetylated structure and the stable ONp-derived amide products provide consistent chemical handles for downstream detection and characterization, while the DL configuration offers practical utility when stereospecificity is not the primary analytical requirement.
4. Pharmaceutical Intermediate Derivatization
Ac-DL-Phe-ONp is frequently applied in pharmaceutical intermediate development as a controlled activated building block for introducing an N-acetyl phenylalanine acyl group into amide-containing intermediates. Process and synthesis teams use ONp esters to access amide derivatives that can serve as precursors to more complex scaffolds, including protected or functionalized intermediates used in route scouting and SAR-supporting chemistry. The reagent's defined acyl functionality and electrophilic ester group make it useful for preparing a range of amide linkages from amine-containing partners, enabling efficient exploration of substitution patterns in late-stage intermediate synthesis.
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