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:

Carboxyl protecting groups

• OMe Protection

• 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.

• 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.

• 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.

• 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.

• 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.

• 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

Name *

Email *

Phone *

Services & Products of Interest * Carboxy-Protected Amino Acids

Project Description

Quantity *

- mg g kg ton

Verification Code *

SUBMIT