Need Assistance?

  • US & Canada:
    +
  • UK: +
Carboxy-Protected Amino Acids

Introduction

Carboxyl group is a very common group in organic synthesis. Because it is relatively active, it has an impact on many reactions. Therefore, it is necessary to protect it. Compared with amino-protecting groups, carboxyl-protecting groups have fewer types and generally exist in the form of salts or esters. The salt is the temporary protection of the carboxyl group, and the commonly used salts are potassium salt, sodium salt, triethylamine salt and tributylamine salt. Commonly used esters are methyl ester, ethyl ester, benzyl ester and tert-butyl ester.

The method of protecting the carboxyl group is mainly esterification, but in some cases, the method of forming an amide or a hydrazide can also be used for protection. The following are several common types of carboxyl protecting groups:

Carboxy-Protected Amino AcidsCarboxyl protecting groups

  • OMe Protection
NameCASCatalogPrice
Fmoc-Aeg-OMe156939-69-4BAT-014368Inquiry
Boc-4-oxo-Pro-Ome102195-80-2BAT-004326Inquiry
Boc-D-trans-Hyp-Ome135042-17-0BAT-004799Inquiry
H-D-Dap(Boc)-OMe363191-25-7BAT-015022Inquiry
Boc-Asp-OMe98045-03-5BAT-007632Inquiry
Boc-D-Val-Ome106391-85-9BAT-008941Inquiry
Boc-Phe(4-I)-OMe113850-76-3BAT-001302Inquiry
Boc-Ser(Tos)-OMe56926-94-4BAT-003012Inquiry
Boc-Val-Ome58561-04-9BAT-008942Inquiry
Z-Trp-Ome2717-76-2BAT-006073Inquiry
Z-Val-Ome24210-19-3BAT-010902Inquiry
N-Me-Ala-OMe35023-55-3BAT-015300Inquiry
H-Met-Ome10332-17-9BAT-008955Inquiry
H-Abu-OMe15399-22-1BAT-015349Inquiry
N-Me-Tyr-OMe70963-39-2BAT-015293Inquiry
H-D-Glu-OMe26566-13-2BAT-007691Inquiry
Ac-DL-Ala(Cl)-Ome18635-38-6BAT-008939Inquiry
  • OEt Protection

Methyl (Me) and ethyl (Et) esters are well suited for a range of synthetic procedures as protecting groups for carboxyl groups. For example, alkylation and condensation reactions are carried out in the form of esters, followed by removal of ester groups by hydrolysis under the catalysis of acids or bases or by pyrolysis.

NameCASCatalogPrice
Boc-Lys-OEt HClBAT-008353Inquiry
Z-D-Glu-OEt97996-97-9BAT-001460Inquiry
Z-Val-OEt67436-18-4BAT-001455Inquiry
H-Pyr-Oet HCl105210-68-2BAT-001489Inquiry
H-D-Nva-OEt HCl1998700-99-4BAT-001567Inquiry
Fmoc-Trp-OEtBAT-001901Inquiry
H-Phg(4-OH)-Oet43189-39-5BAT-002114Inquiry
Boc-Hyp-OEt37813-30-2BAT-004802Inquiry
Boc-Pyr-Oet144978-12-1BAT-004805Inquiry
Boc-Tyr-Oet247088-44-4BAT-003013Inquiry
H-Nva-OEt HCl40918-51-2BAT-004834Inquiry
H-Phe(4-Br)-Oet HCl232276-00-5BAT-002110Inquiry
H-His-OEt · 2 HCl93923-84-3BAT-015673Inquiry
Boc-Aeg-OEt72648-80-7BAT-014370Inquiry
  • OtBu Protection

Tert-butyl (tBu) cannot be hydrogenolyzed, nor can it be hydrolyzed by aminolysis and base catalysis under conventional conditions. But the tert-butyl group can be cleaved off in the form of isobutene under mildly acidic conditions.

NameCASCatalogPrice
Boc-Dap-OtBu HCl1333246-31-3BAT-000951Inquiry
Boc-D-Lys-OtBu63760-73-6BAT-000807Inquiry
Boc-β-iodo-Ala-OtBu1057341-65-7BAT-010881Inquiry
Boc-Tyr-OtBu18938-60-8BAT-000853Inquiry
Boc-Dab-OtBu HCl250611-08-6BAT-000952Inquiry
H-D-Ser-OtBu HCl1033753-14-8BAT-010861Inquiry
Fmoc-Asn-OtBu152781-25-4BAT-001912Inquiry
Fmoc-D-Thr-OtBu1416853-35-4BAT-008448Inquiry
Fmoc-Tyr-OtBu133852-23-0BAT-001905Inquiry
Boc-Dap-OtBu77215-54-4BAT-015351Inquiry
Z-Tyr-OtBu16881-33-7BAT-015031Inquiry
H-D-Abu-OtBu313994-32-0BAT-015312Inquiry
Fmoc-Aeg-OtBu HCl169396-88-7BAT-003644Inquiry
Fmoc-Thr-OtBu120791-76-6BAT-005333Inquiry
H-Arg(Pmc)-OtBu169543-81-1BAT-003943Inquiry
H-Hyp(tBu)-OtBu HCl367453-05-2BAT-000868Inquiry
  • OBzl Protection

Benzyl (Bzl) is a valuable protecting group characterized by its rapid removal by hydrogenolysis. In practical applications, a benzyl protecting group is often used instead of a methyl protecting group to protect the carboxyl group. The benzyl protecting group can be removed by acid treatment or hydrogenolysis under mild conditions.

NameCASCatalogPrice
Boc-D-Pyr-OBzl400626-71-3BAT-001292Inquiry
Boc-Pyr-Obzl113400-36-5BAT-001304Inquiry
Boc-Lys-Obzl HClBAT-000948Inquiry
Z-Hyp-ObzlBAT-001427Inquiry
H-Hyp-Obzl68172-39-4BAT-001490Inquiry
H-Pyr-OBzlBAT-001488Inquiry
H-D-Nle-Obzl109067-70-1BAT-001566Inquiry
H-N-Me-D-Leu-OBzl TosOH1208162-98-4BAT-000871Inquiry
Fmoc-beta-Iodo-D-Ala-ObzlBAT-008706Inquiry
Fmoc-beta-Iodo-L-Ala-Obzl869107-32-4BAT-008708Inquiry
Fmoc-Tyr-Obzl82911-77-1BAT-001902Inquiry
H-Gln-Obzl HCl2419-53-6BAT-010862Inquiry
Fmoc-Thr-Obzl73724-48-8BAT-005332Inquiry
H-Arg(NO2)-Obzl7672-27-7BAT-015672Inquiry
H-Sar-OBzl TosOH54384-06-4BAT-002353Inquiry
  • OPfp Protection

As the carboxyl protecting group of amino acids, Pfp can promote the formation of peptide bonds. Pentafluorophenyl (pfp) protected amino acids can be used for solid-phase and liquid-phase synthesis of peptides.

NameCASCatalogPrice
Fmoc-Cit-OPfp1356537-03-5BAT-014599Inquiry
Fmoc-D-Leu-OPfp184840-63-9BAT-001923Inquiry
Fmoc-D-Met-OPfp210473-10-2BAT-001929Inquiry
Fmoc-D-Phe-OPfp159505-85-8BAT-001933Inquiry
Fmoc-D-Val-OPfp125043-10-9BAT-001943Inquiry
Fmoc-D-Pro-OPfp125281-38-1BAT-002070Inquiry
Fmoc-Asn-OPfp86060-99-3BAT-005296Inquiry
Fmoc-D-Gln-OPfp200622-33-9BAT-005307Inquiry
Fmoc-D-Trp-OPfp136554-94-4BAT-005312Inquiry
Fmoc-Gln-OPfp86061-00-9BAT-005315Inquiry
Fmoc-Ile-OPfp86060-89-1BAT-005317Inquiry
Fmoc-Leu-OPfp86060-88-0BAT-005319Inquiry
Fmoc-Met-OPfp86060-94-8BAT-005324Inquiry
Fmoc-Phe-OPfp86060-92-6BAT-005326Inquiry
Fmoc-Sar-Opfp159631-29-5BAT-004818Inquiry
Fmoc-Trp-OPfp86069-87-6BAT-005334Inquiry
Fmoc-Val-OPfp86060-87-9BAT-005340Inquiry
  • OAll Protection

The most common method of carboxyl protection is via tert-butyl or methyl esters. The common removal conditions for tert-butyl esters are acidic, and the common removal conditions for methyl esters are basic conditions. However, some compounds are unstable to acids and bases, so a carboxyl protecting group that can be removed under neutral conditions is required. The most common such protecting group is the allyl ester (OAll) protecting group. The allyl protecting group can protect the hydroxyl group on the carboxyl group by forming an allyl ether, with high regioselectivity and stereoselectivity, and the reaction conditions for introduction and removal are mild.

NameCASCatalogPrice
Boc-Asp(OAll)-OH DCHABAT-000784Inquiry
Fmoc-Dab-OAll HClBAT-001851Inquiry
Fmoc-Glu(OSu)-OallBAT-001946Inquiry
Fmoc-Lys-Oall161580-12-7BAT-001952Inquiry
H-L-Phe-Oall HClBAT-002174Inquiry
  • Other Protection

Amide and hydrazide protecting groups can be used for peptide synthesis. It can be converted to azide by nitrous acid in peptide synthesis. Yes, the condensation reaction proceeds easily.

Online Inquiry

Verification code
Inquiry Basket