$92.00 - $431.00
Fmoc-D-Asp(OtBu)-OH is an Fmoc-protected D-aspartic acid derivative in which the side-chain beta-carboxyl group is protected as a tert-butyl ester. The alpha-carboxyl group remains available for activation and coupling in standard Fmoc/tBu solid-phase peptide synthesis.
The OtBu protecting group prevents unintended side-chain activation or branching during peptide assembly and is removed during acidic global cleavage. Asp-containing sequences can also be susceptible to sequence- and condition-dependent aspartimide formation, so deprotection time, neighboring residues and synthesis conditions may matter in difficult projects.
Product Information
| Product Name | Fmoc-D-Asp(OtBu)-OH |
| Catalog No. | AS3024 |
| CAS No. | 112883-39-3 |
| Molecular Formula | C23H25NO6 |
| Molecular Weight | 411.45 g/mol |
| Protecting Groups | Fmoc alpha-amino protection; beta-carboxyl OtBu protection |
| Primary Application | D-aspartate incorporation in Fmoc-SPPS |
Application Scope and Assay Relevance
Primary use: Protected D-aspartate building block for peptides requiring an acidic D-residue with the side-chain carboxyl masked during SPPS.
| Typical in vitro relevance | Typical downstream work includes receptor or enzyme SAR, charge/orientation studies, protease-stability assays and conformational comparisons. For the synthesis step itself, Asp-containing sequences may also be monitored for aspartimide-related side products by LC-MS or HPLC. |
| In vivo relevance | Final D-Asp-containing peptides may be studied in vivo after activity and purity are established. Neither the D-configuration nor the acidic side chain alone predicts improved pharmacology. |
Aspartimide is a sequence-dependent synthesis risk
Protected Asp building blocks prevent side-chain coupling, but they do not eliminate aspartimide chemistry under every Fmoc-SPPS condition. Difficult sequences may require adjusted deprotection or backbone-protection strategies.
Purchasing and QC Considerations
Confirm that the ordered material is the side-chain 4-tert-butyl ester, not an alternative protected aspartate isomer. CAS 112883-39-3 and MW 411.45 are useful identity checks.
Frequently Asked Questions
Which carboxyl group is tert-butyl protected?
The D-aspartate side-chain beta-carboxyl group is protected as OtBu.
When is OtBu removed?
It is generally removed during acidic final cleavage.
Why does aspartimide matter?
Certain Asp-containing sequences can cyclize under basic Fmoc-SPPS conditions, creating deletion or rearrangement impurities.
Product Documents
A Material Safety Data Sheet (MSDS) is available for this product to support laboratory handling, storage and safety assessment.
MSDS_Fmoc-D-Asp-OtBu-OH_AS3024
Certificates of Analysis (COAs) are batch-specific. Please contact us to request the COA for your product, and we will provide it by email.
Related Technical Resources
See Fmoc-D-Glu(OtBu)-OH for a closely related building block or synthesis resource.
Browse the complete D-Form Amino Acids category or use Alan Scientific's Chemical Peptide Synthesis service for custom peptides containing D-amino acids.