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Fmoc-D-Thr(Trt)-OH is the D-threonine building block N-alpha-Fmoc-O-trityl-D-threonine. The alpha-amino group carries Fmoc, while the side-chain hydroxyl is protected by trityl (Trt). Supplier documentation identifies the stereochemistry as (2R,3S), which is the D-threonine configuration.
The value of this building block is not simply “D-Thr with a protecting group.” Trt changes the acid sensitivity of the hydroxyl protection and can be useful when the route needs a different deprotection window from conventional tBu-protected threonine.
Product Information
| Product Name | Fmoc-D-Thr(Trt)-OH |
| Catalog No. | AS2112 |
| CAS No. | 682800-84-6 |
| Molecular Formula | C38H33NO5 |
| Molecular Weight | 583.67 g/mol |
| Chemical Identity | N-alpha-Fmoc-O-trityl-D-threonine; (2R,3S) |
| Building Block Type | Fmoc-protected D-amino acid with O-Trt side-chain protection |
| Primary Applications | D-threonine incorporation, Fmoc-SPPS, orthogonal protecting-group design and stereochemical peptide studies |
Trt vs tBu Protection on D-Threonine
Alan also lists Fmoc-D-Thr(tBu)-OH. Both products introduce D-threonine, but Trt and tBu are not equivalent protecting groups. Trityl is generally more acid-labile, so selective or staged deprotection can be possible under conditions where a tert-butyl ether would remain more persistent. The correct choice depends on every other acid-sensitive group in the sequence.
D-Threonine Adds Two Stereochemical Variables
Threonine has stereocenters at both the alpha and beta carbons. The D-Thr identity therefore needs more than a molecular mass match. LC-MS can confirm the expected composition but cannot establish the (2R,3S) stereochemical assignment. We consider enantiomeric or stereochemical documentation important when D/L substitution is being used to interpret a structure-activity relationship.
Use in Fmoc-SPPS
Fmoc is removed under standard base-mediated conditions, leaving the side-chain O-Trt protection in place until the route calls for acid exposure. The broader Fmoc-SPPS workflow and protecting-group logic is useful when deciding whether a selectively acid-labile side chain is an advantage or a liability in a multi-protection sequence.
Procurement and QC Considerations
Confirm CAS 682800-84-6, formula C38H33NO5, MW 583.67 g/mol, (2R,3S) stereochemistry, and O-Trt protection on the threonine hydroxyl. Lot-specific HPLC, identity and enantiomeric-purity data are more informative than mass alone for this product.
For peptides that combine D residues with selective side-chain deprotection, Alan's D-amino-acid and modified peptide synthesis capabilities can be evaluated together with the sequence and modification plan.
Product Documents
A Safety Data Sheet (SDS / MSDS) is available for this product to support laboratory handling, storage and safety assessment.
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 Trt protect in Fmoc-D-Thr(Trt)-OH?
Trt protects the D-threonine side-chain hydroxyl group; Fmoc protects the alpha-amino group.
Is Fmoc-D-Thr(Trt)-OH the same as Fmoc-D-Thr(tBu)-OH?
No. They contain the same D-threonine residue but use different side-chain protecting groups with different acid-lability profiles.
Can LC-MS confirm D-threonine stereochemistry?
No. Mass spectrometry confirms composition but does not by itself establish the D-threonine stereochemical configuration.
Related Technical Resources
Researchers comparing stereochemical building blocks can also browse Alan Scientific's D-form amino acid portfolio. For non-routine protection choices, see the broader specialty building-block collection.