L-Tyrosine allyl ester p-toluenesulfonate salt, commonly written H-Tyr-OAll.TosOH, is an L-tyrosine derivative in which the alpha-carboxyl group is protected as an allyl ester and the amino function is supplied as a p-toluenesulfonate salt. The tyrosine phenolic hydroxyl remains available unless it is protected in a later synthetic step.

The key value of the allyl ester is orthogonality. Allyl carboxyl protection can be removed under Pd(0)-mediated conditions that are distinct from the standard acid- and base-labile protection strategies used in peptide chemistry, enabling selective exposure of a carboxyl group for cyclization, fragment ligation or site-specific modification.

Product Information

What Is Protected in H-Tyr-OAll.TosOH?

The “OAll” notation refers to the carboxyl allyl ester, not to an allyl ether on the phenolic side chain. This distinction is important when searching or ordering tyrosine derivatives because O-allyl side-chain protection and C-terminal allyl ester protection lead to different structures and different synthetic behavior.

The p-toluenesulfonate component is the counterion for the amino-containing tyrosine ester. It should be included in mass and stoichiometric calculations for the supplied salt.

Orthogonal Allyl Ester Deprotection

Allyl esters are valued because they can be removed with palladium(0)-based chemistry under conditions selected to preserve many common Fmoc/tBu or Boc-compatible groups. This can create a free carboxyl group at a controlled stage of synthesis without globally deprotecting the molecule.

Such orthogonality is particularly useful for head-to-tail cyclization precursors, branched peptide construction, fragment condensation and other routes where a carboxyl group must be revealed independently of the N-terminal protecting strategy.

Application Scope

H-Tyr-OAll.TosOH can be used in solution-phase peptide chemistry, orthogonal protected-fragment synthesis, cyclic-peptide precursor preparation and routes requiring a selectively removable tyrosine carboxyl protecting group.

The building block itself is not intended as a direct biological assay reagent. Final peptides prepared from it may subsequently be evaluated in receptor-binding, enzyme, cellular or in vivo studies after complete synthesis and analytical characterization.

Purchasing and QC Considerations

Confirm the L-tyrosine stereochemistry, allyl ester location, tosylate salt form, CAS identity and total molecular weight. The formula may also be represented as C₁₂H₁₅NO₃ . C₇H₈O₃S; this component notation describes the same 1:1 salt as the combined formula C₁₉H₂₃NO₆S.

Product Documents

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

MSDS_L-Tyrosine-allyl-ester-p-toluenesulfonate-salt_AS4051

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 does OAll mean in H-Tyr-OAll.TosOH?

It means the tyrosine carboxyl group is protected as an allyl ester.

Why use an allyl ester in peptide synthesis?

It provides an orthogonal carboxyl-protection strategy that can be removed under palladium-mediated conditions without necessarily removing common acid- or base-labile groups.

Is the tyrosine phenolic OH allyl-protected in this product?

No. The product name refers to the carboxyl allyl ester; it should not be confused with an O-allyl-protected tyrosine phenol.

Related Technical Resources

Explore additional Specialty Peptide Building Blocks for protected fragments, linker motifs and peptide-synthesis intermediates.

For sequence-specific synthesis, protected-fragment assembly and modified peptide projects, see our Chemical Peptide Synthesis service.

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