Boc-(S)-2-thienylglycine is a Boc-protected, S-configured non-natural amino acid that replaces the phenyl ring of phenylglycine-like chemistry with a thiophene heteroaromatic group. The building block provides a compact route for introducing a 2-thienyl substituent next to the peptide backbone while preserving a defined stereocenter.

This type of heteroaromatic amino acid is useful in peptide and peptidomimetic SAR when researchers want to probe aromatic size, sulfur-containing heteroaromatic interactions, lipophilicity and stereochemical recognition without simply substituting a conventional proteinogenic residue.

Product Information

Why Use a 2-Thienylglycine Building Block?

The thiophene ring is an aromatic heterocycle with electronic and steric properties that differ from phenyl and other common aromatic side chains. Incorporation of a thienylglycine residue can therefore be used to test how a binding pocket tolerates heteroaromatic sulfur, altered ring electronics and a compact aryl-like substituent. The effect is target-dependent and should be evaluated experimentally in the final peptide or peptidomimetic.

Stereochemistry: S vs R Thienylglycine

Boc-(S)-2-thienylglycine and Boc-(R)-2-thienylglycine are enantiomeric building blocks and should not be treated as interchangeable. Their molecular formula and nominal molecular weight are the same, so identity requires the correct CAS number, defined structure and, when relevant, chiral or optical-rotation documentation. The S product uses CAS 40512-56-9; the corresponding R building block in this catalog uses CAS 74562-03-1.

Applications in Peptide and Peptidomimetic Research

Typical use cases include non-natural amino-acid scanning, receptor- or enzyme-ligand SAR, peptidomimetic design, heteroaromatic residue substitution and synthesis of protected intermediates for medicinal chemistry. Peptides containing the residue may later be evaluated in biochemical, binding, enzyme or cell-based assays, but the protected building block itself is an upstream synthetic reagent rather than a direct assay compound.

Coupling and Deprotection Considerations

The Boc group is acid-labile and is normally removed under acidic conditions appropriate to the broader protecting-group strategy. Coupling conditions should be chosen with attention to stereochemical integrity because the alpha carbon is chiral; extended activation and unnecessarily strong base exposure should be avoided when epimerization is a concern.

Procurement and QC Considerations

For stereochemically defined non-natural amino acids, a correct name and mass alone are not sufficient. Confirm CAS 40512-56-9, structure, assay and lot-specific stereochemical identity on the COA. This is particularly important because the R enantiomer has the same formula and molecular weight.

Product Documents

A Material Safety Data Sheet (MSDS) is available for this product to support laboratory handling, storage and safety assessment.

MSDS_Boc-S-2-thienylglycine_AS4046

Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.

Frequently Asked Questions

What is Boc-(S)-2-thienylglycine used for?

It is used as a protected non-natural amino acid for peptide SAR, peptidomimetic synthesis and heteroaromatic residue incorporation.

Is the S isomer interchangeable with Boc-(R)-2-thienylglycine?

No. They are enantiomers. The same formula and molecular weight do not establish stereochemical identity.

Is the thiophene ring removed during peptide cleavage?

No. The thiophene is part of the residue side chain; the Boc protecting group is the removable functionality.

Related Technical Resources

Browse additional Specialty Peptide Building Blocks for protected fragments, non-natural residues and peptide-synthesis intermediates.

For projects using this chemistry in a complete research workflow, explore Alan Scientific's custom synthesis of non-natural peptide sequences.

Research Use Only.