Fmoc-Sieber-PS Resin丨CAS 915706-90-0

Fmoc-Sieber-PS resin丨CAS 915706-90-0 is a specialized solid-phase support used extensively in peptide synthesis, combinatorial chemistry, and small molecule synthesis, particularly when mild cleavage conditions are necessary.

1. Peptide Synthesis (SPPS)

a. C-terminal Peptide Synthesis

The Sieber linker allows for the synthesis of peptides with free C-terminal carboxylic acids, amides, or modified termini.

Compatible with Fmoc (base-labile) strategies, enabling stepwise peptide elongation under standard solid-phase peptide synthesis (SPPS) conditions.

b. Mild Cleavage Conditions

Peptides can be cleaved from the resin under mildly acidic conditions (e.g., 1% TFA in DCM), preserving acid-sensitive side-chain protecting groups.

This feature makes it ideal for fragment condensation or branching strategies in complex peptide synthesis.

c. Partial Cleavage Monitoring

Because cleavage is mild and selective, small portions of the peptide can be released for analytical testing (e.g., HPLC, MS) without compromising the rest of the resin-bound product.

2. Combinatorial Library Synthesis

Fmoc-Sieber-PS resin is widely used in combinatorial chemistry for the synthesis of peptidomimetics, small-molecule libraries, and bioactive compound screening sets.

The stability of the linker under various synthetic conditions and selective cleavage enhances library fidelity and throughput.

3. Branching and Cyclization Strategies

The Sieber linker enables synthesis of complex, branched, or cyclic peptides, often requiring orthogonal deprotection steps.

Ideal for head-to-tail cyclization or side-chain functionalization in constrained or bioactive peptide architectures.

1. Mild, Selective Cleavage

The Sieber linker is cleaved under mild acidic conditions, preserving side-chain protections and enabling orthogonal synthesis pathways.

Suitable for intermediate cleavage, making it advantageous for on-resin modifications, fragment analysis, or multi-step synthesis workflows.

2. High Compatibility with Fmoc-SPPS

Fully compatible with standard Fmoc chemistry, which avoids harsh acidic or oxidative conditions.

Widely adopted in both academic and industrial peptide synthesis laboratories.

3. Reduced Side Reactions

The polymer support and linker design minimize resin-based side reactions, such as diketopiperazine formation or racemization at the C-terminus.

Provides high-purity peptides with excellent reproducibility.

4. Ideal for Protected Peptide Fragments

Enables the synthesis and isolation of fully protected peptide intermediates, which are crucial in fragment coupling or convergent assembly approaches.

5. Versatility in Cleavage Options

Fmoc-Sieber-PS resin丨CAS 915706-90-0 can be used to produce peptides with free carboxylic acid, amide, or modified C-termini depending on the cleavage and post-cleavage treatment strategy.

Final cleavage (global deprotection) is typically performed with standard TFA cocktails after the peptide has been cleaved from the resin.

Fmoc-Sieber-PS resin丨CAS 915706-90-0 is a versatile and highly functional solid-phase support tailored for mild acid-labile peptide synthesis. Its unique Sieber linker enables the selective release of protected peptides, making it ideal for fragment condensation, combinatorial chemistry, and complex peptide architectures. With its compatibility with Fmoc chemistry, stability under synthesis conditions, and utility in orthogonal synthetic strategies, Fmoc-Sieber-PS resin remains an essential tool in modern peptide and bioorganic synthesis.