Ligation thiazolidine

Recently, Tam et al. extended their orthogonal ligation concept, using the thermodynamically driven formation of a thiazolidine ring for the synthesis of dendritic compounds that carry cyclic peptides at the surface, which were designated multiple cyclic antigen peptides (McAPs) [18,19]. 

The protonated nature of the Nt-cysteinyl thiol Inhibits thloester ligation but permits imine capture of the Ct-glycoaldehyde ester and it s tautomerization to a stable thiazolidine ester 4. (Adapted from Tam et ah, 2001)... 

Scheme 1 Examples of Chemoselective Ligation Strategies Resulting in the Formation of Nonpeptidic Bonds (a) Hydrazone, (b) Oxime, (c) Thiazolidine...

In addition to homodetic cyclic peptides, chemical ligation methods have been developed that lead to heterodetic cyclic peptides containing thiazolidine. 158-161 ... 

The second type of weak bases for imine ligations are 1,2- or 1,3-heterosubstituted amines of amino thiols and amino alcohols. Of the two, the amino thiols appear to be the more suitable choice because they form stable thiazolidine derivatives under very mild reaction condi-tions 84"89,114 121 140 Furthermore, the 1,2-and 1,3-aminothiol moieties are found in cysteines and homocysteines that form a stable heterocyclic ring with an aldehyde within ten minutes at pH 4-5. Thiazolidine ring formation has been successfully used to ligate both linear and constrained peptides to K2K dendron types of cores and proteins containing a-oxoacyl groups. 

Ligation Conditions of Peptide Dendrimer Formation through Oxime, Hydrazone, and Thiazolidine Ligations To Form 64, 66, or 70 [85 ... 

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