55559-26-7

Upstream product

• 56-41-7 L-alanin 
• 55559-13-2 (S)-2-Benzyloxycarbonylamino-4-carbamoyl-butyric acid 3-ethylcarbamoyl-2-hydroxy-phenyl ester 
• 7763-16-8 N²-benzyloxycarbonyl-L-glutamine-(4-nitro-phenyl ester) 
• 850232-63-2 benzyl N-[(1S)-4-amino-1-(1H-1,2,3-benzotriazol-1-ylcarbonyl)-4-oxobutyl]carbamate 
• 2650-64-8 Cbz-L-Gln 
• 78346-96-0 N-(N²-benzyloxycarbonyl-L-glutaminyl)-L-alanine ethyl ester 

Relevant academic research and scientific papers

The efficient preparation of di- and tripeptides by coupling N-(Cbz- or Fmoc-α-aminoacyl)benzotriazoles with unprotected amino acids

N-(Cbz- or Fmoc-α-aminoacyl)benzotriazoles 2 and N-protected peptidoylbenzotriazoles 6 are coupled in aqueous acetonitrile solution with free amino acids or dipeptides to prepare: (i) 22 chirally pure dipeptides 5a-v (in an average yield of 82%) from N-(Cbz- or Fmoc-α-aminoacyl)benzotriazoles 2 and unprotected amino acids, (ii) five chiral tripeptides 7a-e (in an average yield of 75%) from N-protected peptidoylbenzotriazoles 6 and unprotected amino acids, (iii) one chiral tripeptide 7g (62%) from N-(Cbz- or Fmoc-α- aminoacyl)benzotriazole 2a and the free dipeptide 8. In all, N-(Cbz- or Fmoc-α-aminoacyl)benzotriazole derivatives of 17 of the 20 naturally occurring amino acids were used, including those containing the following unprotected side chain functionalities: alcoholic -OH (Ser), indole -NH (Trp), imidazole -NH, phenolic -OH (Tyr), -CONH2 (Gln, Asn), -SH (Cys), -CO2H (Glu, Asp), and -S-S (Cystine). Support for the complete retention of chirality was obtained by parallel experiments involving D-Ala, L-Ala, and DL-Ala for the preparation of di- and tripeptides. This and other evidence for chiral integrity was supported by NMR and HPLC analyses. Georg Thieme Verlag Stuttgart.

Peptide coupling of unprotected amino acids through in situ p-nitrophenyl ester formation

Several series of dipeptides and tripeptides were prepared via an activation-coupling method involving the in situ formation of a p-nitrophenyl ester of an (N-protected) amino acid, followed by coupling with an unprotected amino acid in partially aqueous solutions. The resulting peptide is easily isolated by precipitation. In general, the yields obtained are good to excellent and racemization is minimal. This method is particularly advantageous with respect to its simplicity and lack of obligatory side chain protection/deprotection steps.