- The efficient preparation of di- and tripeptides by coupling N-(Cbz- or Fmoc-α-aminoacyl)benzotriazoles with unprotected amino acids
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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.
- Katritzky, Alan R.,Angrish, Parul,Suzuki, Kazuyuki
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- Tandem deprotection-dimerization-macrocyclization route to C2 symmetric cyclo-tetrapeptides
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Dimerization-macrocyclization has been a long-standing problem in the cyclization of peptides since, together with the desired cyclic product, many cyclic oligomers and linear polymers may also be formed during the reaction. Therefore, the development of a process that affords the cyclic dimer predominantly is difficult. A novel and versatile strategy for the synthesis of symmetric cyclo-tetrapeptides by palladium-promoted tandem deprotection/cyclo- dimerization from readily available Cbz-dipeptidoyl benzotriazolides is reported (Cbz=carboxybenzyl).
- Ha, Khanh,Lebedyeva, Iryna,Hamedzadeh, Sadra,Li, Zhiliang,Quinones, Ryan,Pillai, Girinath G.,Williams, Byron,Nasajpour, Amir,Martin, Kristin,Asiri, Abdullah M.,Katritzky, Alan R.
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supporting information
p. 4874 - 4879
(2014/05/06)
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- Total synthesis of cyclic heptapeptide Rolloamide B
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The first total synthesis of Rolloamide B, a cyclic proline-enriched heptapeptide, is reported. This work features solution phase benzotriazole-mediated peptide synthesis ligating native amino acids. The Royal Society of Chemistry 2013.
- Khatib, Mirna El,Elagawany, Mohamed,?ali?kan, Eray,Davis, Emily Faith,Faidallah, Hassan M.,El-Feky, Said A.,Katritzky, Alan R.
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supporting information
p. 2631 - 2633
(2013/05/08)
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- Triphenylphosphoranylidene substituted heterocycles as versatile intermediates
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N-Cbz-(α-aminoacyl)benzotriazoles 5a-e reacted with (stabilized-methylene)triphenylphosphoranes 6 and 13 to give the corresponding esters 7a-e (66-91%) or nitriles 14a-e (63-85%). Deprotection of N-Cbz-γ-amino-β-oxo-α-triphenylphosphoranylidene esters 7a-
- Katritzky, Alan R.,Vincek, Adam S.,Steel, Peter J.
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experimental part
p. 1401 - 1423
(2009/07/17)
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