Boc-Ile-OSu

Boc-Ile-OSu is a Boc-protected isoleucine N-hydroxysuccinimyl ester (OSu), combining a protected amino group with an activated carboxylate for efficient amide bond formation. As an amino acid ester designed for peptide and intermediate synthesis, it is commonly handled as a reactive coupling building block where the Boc group provides temporary protection of the amino functionality during downstream assembly. The isoleucine side chain supports incorporation of a hydrophobic, aliphatic residue in peptide sequences and in structure-defined intermediates used for medicinal chemistry and chemical biology workflows.

1. Peptide Coupling Building Block

Boc-Ile-OSu is used as an activated amino acid ester for coupling steps in peptide synthesis workflows, particularly when chemists prefer an ester-activated carboxylate strategy to form the next amide linkage. Research groups and custom peptide manufacturers employ this reagent to assemble Boc-protected peptide segments and to prepare peptide intermediates where the Boc group must remain intact through the coupling operation. The isoleucine side chain contributes the characteristic branched hydrophobic residue that is frequently required for sequence-defined peptides, SAR (structure-activity relationship) studies, and fragment-based lead optimization. Because the OSu leaving group is designed to promote efficient amide formation, Boc-Ile-OSu is typically selected when rapid, high-yield coupling of the next residue is needed during iterative chain assembly.

2. Protected Peptide Intermediate Synthesis

Boc-Ile-OSu is also applied to the preparation of protected peptide intermediates used in longer, multi-step peptide assembly and purification workflows. In medicinal chemistry and peptide chemistry development, this reagent helps convert a Boc-protected isoleucine unit into a form that can be incorporated into larger protected structures without exposing the amino group prematurely. Teams developing peptide libraries or sequence variants often use activated amino acid esters like Boc-Ile-OSu to standardize the introduction of the same residue across multiple analogs, improving reproducibility from one intermediate batch to the next. The combination of Boc protection and OSu activation supports downstream handling as a discrete intermediate, enabling controlled progression toward the final peptide construct.

3. Amide-Linkage Formation in Medicinal Chemistry

Boc-Ile-OSu finds use beyond peptide assembly in medicinal chemistry programs where an isoleucine-derived amide linkage is required for constructing peptidomimetic motifs, constrained scaffolds, or side-chain-bearing intermediates. Process and synthesis teams use this activated amino acid ester to install an isoleucine carboxyl-derived amide onto appropriately functionalized amines, supporting the rapid generation of analog series for SAR exploration. The reagent's protected amino functionality (Boc) helps maintain orthogonality during intermediate elaboration, allowing chemists to defer deprotection and further functionalization until later stages of the synthesis plan. This makes Boc-Ile-OSu a practical choice when a stable, isolable amino acid derivative is needed as a coupling reagent for building amide-containing structures with an isoleucine motif.

4. Custom Peptide Manufacturing Research

Boc-Ile-OSu is commonly used in custom peptide manufacturing research and method development settings where coupling efficiency, intermediate stability, and step-to-step consistency are critical. Peptide synthesis groups may evaluate OSu-activated amino acid esters as part of their internal coupling protocols to optimize yields and minimize side reactions during the assembly of Boc-protected peptide segments. The reagent's design supports incorporation of a specific, hydrophobic isoleucine residue while maintaining the Boc-protected amino group for controlled continuation of the synthesis sequence. In practice, this aligns with the needs of laboratories producing sequence-defined intermediates for subsequent deprotection, purification, and final peptide processing.

1. Myotropic activity and immunolocalization of selected neuropeptides of the burying beetle Nicrophorus vespilloides (Coleoptera: Silphidae)

2. The effect of sex on immune responses to a homocitrullinated peptide in the DR4-transgenic mouse model of Rheumatoid Arthritis

3. Immune responses to homocitrulline-and citrulline-containing peptides in rheumatoid arthritis

4. Proinsulin C-peptide and insulin: Limited pattern similarities of interest in inter-peptide interactions but no C-peptide effect on insulin and IGF-1 receptor signaling

5. C-peptide and its C-terminal fragments improve erythrocyte deformability in type 1 diabetes patients