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Boc-Pip(Fmoc)-OH is an orthogonally protected 4-aminopiperidine-4-carboxylic acid scaffold. The shorthand name can be misleading unless the protection map is stated explicitly: Boc protects the exocyclic 4-amino group, while Fmoc protects the piperidine ring nitrogen. The carboxylic acid is also located at the 4-position.
This arrangement creates a rigid, nitrogen-containing scaffold with two chemically distinct amino functions that can be managed in different stages of a synthesis. That is the main reason to treat Boc-Pip(Fmoc)-OH as a specialized peptidomimetic building block rather than as a conventional alpha-amino acid.
Product Information
| Product Name | Boc-Pip(Fmoc)-OH |
| Catalog No. | AS2111 |
| CAS No. | 368866-07-3 |
| Molecular Formula | C26H30N2O6 |
| Molecular Weight | 466.53 g/mol |
| Chemical Identity | 4-[(tert-butoxycarbonyl)amino]-1-[(9H-fluoren-9-ylmethoxy)carbonyl]-4-piperidinecarboxylic acid |
| Building Block Type | Orthogonally protected constrained diamino acid / piperidine scaffold |
| Primary Applications | Peptidomimetic synthesis, constrained scaffold design, selective amine functionalization and medicinal chemistry |
Why the Protection Map Matters
Fmoc is base-labile and Boc is acid-labile. In a route designed around selective deprotection, the ring nitrogen and exocyclic amino group can therefore be addressed at different points. We recommend drawing the structure in the synthetic plan rather than relying on “Pip(Fmoc)” shorthand, because a reversed assumption about which nitrogen carries Fmoc changes the entire reaction sequence.
Constrained Piperidine Geometry
The piperidine ring places the 4-amino and 4-carboxyl functions on a constrained cyclic framework. This can be useful in peptidomimetic or medicinal-chemistry programs that need to alter the distance and orientation between functional groups. The broader design logic is similar to other noncanonical residues used to reshape peptide architecture, but this scaffold should be evaluated as its own chemical entity.
Coupling and Selective Functionalization
The free carboxylic acid can be activated to form amide bonds. Subsequent exposure of either nitrogen depends on the intended orthogonal deprotection sequence and on other acid- or base-sensitive groups present in the molecule. For complex sequences, we consider protecting-group compatibility a project-level constraint, not a property that can be judged from this building block in isolation.
Procurement, Storage and QC
Confirm CAS 368866-07-3, formula C26H30N2O6, MW 466.53 g/mol, and the exact N-Boc/N-Fmoc positional assignment. Public supplier documentation specifies sealed, dry storage at 2-8°C. It also classifies the material as harmful if swallowed and as a skin, eye and respiratory irritant, so the product-specific SDS should be reviewed before handling.
When this scaffold is intended for a peptide or peptidomimetic sequence, custom synthesis using constrained and specialty amino-acid building blocks can be evaluated with the full protection and deprotection 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
Where are the Boc and Fmoc groups in Boc-Pip(Fmoc)-OH?
Boc protects the exocyclic 4-amino group, while Fmoc protects the piperidine ring nitrogen.
Why is this considered an orthogonally protected scaffold?
Fmoc and Boc respond to different deprotection conditions, allowing the two nitrogen functions to be managed at different stages of a synthesis.
Is Boc-Pip(Fmoc)-OH a standard alpha-amino acid?
No. It is a constrained 4-aminopiperidine-4-carboxylic acid scaffold used in peptidomimetic and medicinal-chemistry synthesis.
Related Technical Resources
For alternative constrained or non-proteinogenic scaffolds, browse unusual amino acids and analogs. For more route-oriented building blocks, see specialty peptide building blocks.