FREE shipping to on qualifying orders when you spend or more, processed by Ossila BV. All prices ex. VAT. Qualifying orders ship free worldwide! Fast, secure, and backed by the Ossila guarantee. It looks like you are visiting from , click to shop in or change country. Orders to the EU are processed by our EU subsidiary.

It looks like you are using an unsupported browser. You can still place orders by emailing us on info@ossila.com, but you may experience issues browsing our website. Please consider upgrading to a modern browser for better security and an improved browsing experience.

N-Boc-4,4-difluoro-L-proline

CAS Number 203866-15-3

Fluorinated Building Blocks, Heterocyclic Building Blocks, Materials, Monomers


Product Code B2521-500mg
Price £70 ex. VAT

A difluorinated l-proline derivative

Used as a molecular scaffold for biochemistry and a conformational tool for polypeptides


Specifications | MSDS | Literature and Reviews


N-Boc-4,4-difluoro-l-proline (CAS number 203866-15-3) is a tert-butoxycarbonyl (Boc) protected l-proline with two fluorine substituents at 4-position. N-Boc-4,4-difluoro-l-proline is an S-enantiomer, making it an excellent additive/catalyst in asymmetric reactions. In protein/peptide chemistry, N-Boc-4,4-difluoro-l-proline is introduced for conformational control favouring 78% cis-conformers. The conformation selectivity is also expressed in the 19F NMR spectrum which is a powerful tool to study the isomerisation of peptides and proteins.

N-Boc-4,4-difluoro-l-proline is also applied as a molecular scaffold for synthesising fibroblast activation protein, a trans-membrane serine protease.

Multiple functional groups

Multiple functional groups

For facile synthesis

Fluorinated building block

Fluorinated l-proline building block

For organic synthesis, medicinal chemistry and biochemistry research

Worldwide shipping for 203866-15-3

Worldwide shipping

Quick and reliable shipping

High purity 203866-15-3

High purity

>97% High purity

General Information


CAS Number 203866-15-3
Chemical Formula C10H15F2NO4
Full Name (S)-1-(tert-Butoxycarbonyl)-4,4-difluoro-2-pyrrolidinecarboxylic acid
Molecular Weight 251.23 g/mol
Synonyms N-(tert-Butoxycarbonyl)-4,4-difluoro-l-proline
Classification / Family Fluorinated building blocks, Heterocyclic building blocks, Proteins, Peptides, Asymmetric synthesis, Chiral molecules

Chemical Structure


N-Boc-4,4-difluoro-L-proline chemical structure, CAS 203866-15-3.
N-Boc-4,4-difluoro-l-proline chemical structure, CAS 203866-15-3

Product Details


Purity 97%
Melting Point Tm = 120 °C – 140 °C
Optical Rotation −44.19 ° (c = 1, methanol)
Appearance Off-white powder

MSDS Documentation


N-Boc-4,4-difluoro-L-proline MSDS SheetN-Boc-4,4-difluoro-l-proline MSDS Sheet

Literature and Reviews


  1. Deciphering the fluorine code—the many hats fluorine wears in a protein environment, A. Berger et al., Acc. Chem. Res., 2017, 50, 2093–2103(2017); DOI: 10.1021/acs.accounts.7b00226.
  2. Minimising conformational bias in fluoroprolines through vicinal difluorination, G.-J. Hofman et al., Chem. Commun., 54, 5118(2018); DOI: 10.1039/c8cc01493k.
  3. Fluorinated prolines as conformational tools and reporters for peptide and protein chemistry, S. Verhoork et al., Biochemistry, 57(43), 6132–6143(2018); DOI: 10.1021/acs.biochem.8b00787.
Return to the top