L-Cyclobutylalanine is a naturally occurring amino acid analogue in which the side chain is a cyclobutyl-substituted alkyl group attached to the alpha carbon, classifying it as an aliphatic, non-aromatic amino acid. The molecule contains a free amino group and a free carboxyl group, with the cyclobutyl ring providing a constrained, hydrophobic steric environment that can influence conformational preferences in peptide backbones when incorporated. L-Cyclobutylalanine is used in peptide synthesis and structure-activity or conformational studies to probe how ring-constrained side chains affect amide formation, peptide geometry, and analytical properties of amino acid-containing intermediates.
CAT No: CP20801
L-Cyclobutylalanine is an L-configured amino acid featuring a cyclobutyl side chain attached to the α-carbon, providing a compact, conformationally constrained hydrophobic moiety that can influence backbone and side-chain packing in peptides and foldamers. The molecule contains a primary amino group and a carboxylic acid functionality, enabling standard amino acid coupling chemistry and straightforward conversion into protected amino acid derivatives or activated esters. The cyclobutane ring contributes increased steric definition and can alter rotamer preferences relative to linear alkyl analogs, making it a useful chiral building block for structure-focused peptide design. L-Cyclobutylalanine is typically handled as the free amino acid or converted into N-protected, C-activated, or esterified forms to support peptide synthesis compatibility and downstream synthetic transformations.
1. Peptide Synthesis
L-Cyclobutylalanine is applied in peptide building block preparation where its L-stereocenter and amino acid backbone support amide bond formation under standard peptide coupling conditions. The carboxyl group can be converted into activated derivatives or ester forms, while the amino functionality is commonly protected to control chemoselectivity during stepwise chain assembly. The cyclobutyl side chain functions as a hydrophobic, conformationally informative residue that can be incorporated into peptides to probe how constrained alkyl groups affect secondary-structure propensity and protease recognition. L-Cyclobutylalanine-derived residues can be used to generate peptide analogs for library synthesis and medicinal chemistry lead optimization workflows.
2. Peptidomimetics Design
L-Cyclobutylalanine is used in peptidomimetic and foldamer construction where the cyclobutyl side chain provides steric and conformational bias distinct from alanine or cyclopentylalanine analogs. The amino acid's protected N-terminus and carboxyl-derived functionality enable incorporation into constrained scaffolds while maintaining stereochemical fidelity at the α-carbon. Side-chain hydrophobicity and ring strain can be leveraged to tune molecular recognition in receptor-binding studies and to modulate physicochemical properties such as local packing and solvent exposure. L-Cyclobutylalanine can serve as a chiral intermediate for generating noncanonical amino acid patterns in synthetic biology and chemical biology probes.
3. Chemical Biology Probes
L-Cyclobutylalanine is suitable for chemical biology research where amino acid incorporation into peptide tags, affinity handles, or substrate analogs enables controlled labeling and interaction studies. The primary amino and carboxylic acid groups can be transformed into N-protected derivatives and C-terminal variants that support conjugation-ready peptide fragments. The cyclobutyl side chain may influence binding orientation and residence time in protein-ligand interaction assays by altering steric complementarity without introducing strongly reactive functional groups. L-Cyclobutylalanine-based peptide fragments can be used to create molecular tools for studying biomolecular recognition, trafficking motifs, and enzyme-substrate specificity.
4. SAR Studies
L-Cyclobutylalanine is employed in structure-activity relationship studies as a stereochemically defined hydrophobic residue for systematic side-chain variation. The L-configuration allows direct comparison against other α-amino acid analogs while the cyclobutyl ring provides a constrained alkyl environment that can shift conformational ensembles in peptide or peptidomimetic series. N-protection and carboxyl activation strategies enable consistent incorporation into analog panels, supporting parallel synthesis of SAR libraries. L-Cyclobutylalanine-derived analogs can be applied as chiral building blocks for mapping how steric bulk and side-chain rigidity affect binding and stability trends in applied medicinal chemistry research.
5. Pharmaceutical Intermediate Preparation
L-Cyclobutylalanine is relevant to pharmaceutical intermediate preparation where amino acid derivatives are required for downstream synthesis of peptide-like active ingredients and related intermediates. The free amino acid can be converted into N-protected amino acid forms and C-terminal functional derivatives that participate in controlled coupling steps during manufacturing-scale fine chemical synthesis. The cyclobutyl side chain can be retained through multi-step sequences, supporting the generation of stereodefined intermediates for process chemistry routes. L-Cyclobutylalanine thus functions as a chiral amino acid intermediate for producing defined building blocks used in industrial peptide construction and specialty chemical production.
6. Industrial Fine Chemical Synthesis
L-Cyclobutylalanine is applied in industrial fine chemical synthesis as a chiral, noncanonical amino acid feedstock for producing protected amino acid derivatives and peptide-coupling intermediates. The presence of both amino and carboxylic acid functionalities enables conversion into manufacturable protected forms, such as N-protected derivatives and ester or activated carboxyl equivalents, supporting scalable peptide coupling chemistry. The cyclobutyl side chain provides a reproducible steric motif that can be carried through synthetic sequences to generate consistent product profiles in peptide and peptidomimetic manufacturing. L-Cyclobutylalanine-based intermediates can be utilized for specialty chemical production where stereochemical integrity and functional-group compatibility are required for reliable downstream assembly.
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