- Indium-mediated mild and facile method for the synthesis of amides
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Indium-mediated coupling reactions of acyl chlorides and amines for the synthesis of amide bonds are described. The reaction afforded high yields of the desired amides under mild and neutral conditions, and it was applicable also to the preparation of peptides without epimerization.
- Cho, Dae Hyan,Jang, Doo Ok
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- N-Silylation of amines and amino acid esters under neutral conditions employing TMS-Cl in the presence of zinc dust
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An expedient synthetic approach to N-silylamines has been developed. The protocol, using TMS-Cl/zinc dust instead of BSA, is useful for the conversion of amines or amino acid esters to the corresponding silyl derivatives, followed by acylation with an acyl chloride or Fmoc-amino acid chloride to give the corresponding amide or peptide. This procedure, affording products in good to excellent yields, is also efficient for the coupling of sterically hindered amino acids like α,α-dialkylamino acids and NMe-amino acids. Further, the use of an equimolar quantity of organic base, such as Et 3N/pyridine, is circumvented.
- Suresh Babu, Vommina V.,Vasanthakumar, Ganga-Ramu,Tantry, Subramanyam J.
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- Peptide Bond Formation via Nα-Protected Diacyldiselenides
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Abstract: A simple, straightforward, for the peptide bond formation employing corresponding carboxylic acids and amines derived from amino acids via Nα-protected diacyldiselenide is delineated. The key step of the synthesis is the in situ gener
- Vathsala,Roopesh Kumar,Sagar,Mahesh,Venkata Ramana,Sureshbabu, Vommina V.
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- Eco-friendly synthesis of peptides using fmoc-amino acid chlorides as coupling agent under biphasic condition
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Background: Agro-waste derived solvent media act as a greener process for the peptide bond formation using Nα-Fmoc-amino acid chloride and amino acid ester salt with in situ neutralization and coupling under biphasic condition. The Fmoc-amino acid chlorides are prepared by the reported procedure of freshly distilled SOCl2 with dry CH2Cl2. The protocol found many added ad-vantages such as neutralization of amino acid ester salt and not required additional base for the neu-tralization, and directly coupling take place with Fmoc-amino acid chloride gave final product dipeptide ester in good to excellent yields. The protocol occurs with complete stereo chemical integrity of the configuration of substrates. Here, we revisited Schotten-Baumann condition, instead of using inorganic base. Objective: To develop green protocol for the synthesis of peptide bond using Fmoc-amino acid chloride with amino acid esters salt. Methods: The final product isolated is analyzed in several spectroscopic and analytical techniques such as FT-IR,1H-,13C-NMR, Mass spectrometry and RP-HPLC to check stereo integrity and puri-ty of the product. Conclusion: The present method developed greener using natural agro-waste (lemon fruit shell ash) derived solvent medium for the reaction and not required chemical entity.
- Kantharaju, Kamanna,Khatavi, Santosh Y.
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p. 699 - 707
(2021/08/23)
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- Iodine-Mediated Oxidative Coupling of Hydroxamic Acids with Amines towards a New Peptide-Bond Formation
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An efficient and straightforward approach for the coupling of Nα-protected hydroxamic acids with an amino component in the presence of iodine is delineated. The reaction is mediated by the formation of unstable but reactive acyl nitroso intermediates. The peptide hydroxamic acids were found to be useful substrates in coupling reactions.
- Krishnamurthy, Muniyappa,Vishwanatha,Panguluri, Nageswara Rao,Panduranga,Sureshbabu, Vommina V.
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supporting information
p. 2565 - 2569
(2015/11/16)
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- Synthesis of peptides employing protected-amino acid halides mediated by commercial anion exchange resin
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Coupling of protected-amino acid halides (chloride, fluoride) mediated by commercial anion exchange resin for the solution phase synthesis of peptides is described. The reaction was carried out in an organic medium, circumventing the use of an organic base or an inorganic base. The coupling is fast, clean and racemization free. The anion exchange resin functions as a solid-phase basic scavenger, soaking up the HCl produced and allowing the amine to react. The method is extended for the coupling of sterically hindered α,α,- dialkylamino acids. Graphical Abstract: [Figure not available: see fulltext.]
- Bhaskara Redddy,Kumari, Y. Bharathi,Ananda, Kuppanna
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p. 225 - 229
(2013/12/04)
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- Synthesis of selenoxo peptides and oligoselenoxo peptides employing LiAlHSeH
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Synthesis of selenoxo peptides by the treatment of Nα- protected peptide esters with a combination of PCl5 and LiAlHSeH is delineated. The method is simple, high-yielding, and free from racemization. Thus obtained selenoxo peptides are used as units for N-terminal chain extension through Nα-deprotection/coupling to yield peptide-selenoxo peptide hybrids. Multiple selenation is demonstrated by conversion of two peptide bonds of tripeptides into selenoxo peptide bonds. Amino acid derived arylamides are also converted into aryl selenoamides. C6H 5-CSeNH-Val-OMe 8f is obtained as single crystal, and its structure was determined through X-ray diffraction study.
- Vishwanatha,Narendra,Chattopadhyay, Basab,Mukherjee, Monika,Sureshbabu, Vommina V.
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experimental part
p. 2689 - 2702
(2012/06/01)
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- HOAt.DCHA as co-coupling agent in the synthesis of peptides employing Fmoc-amino acid chlorides as coupling agents: Application to the synthesis of ss-casomorphin
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A simple, efficient and racemization free method for the synthesis of peptides employing Fmoc-amino acid chlorides mediated by HOAtDCHA as a co-coupling agent has been described. This protocol is successfully employed in the synthesis of the pentapeptide H-Pro-Gly-VaI-GIy-VaI-OH (PGVGV), and ss-casomorphin (H-Tyr-Pro-Phe-Pro-Gly-OH) in 85 and 80% yields, respectively.
- Sureshbabu, Vommina V.,Chennakrishnareddy, Gundala
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experimental part
p. 981 - 988
(2009/12/28)
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- HOBt·DCHA-mediated synthesis of sterically hindered peptides employing Fmoc-amino acid chlorides in both solution-phase and solid phase methods
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The synthesis of peptides employing Fmoc-amino acid chlorides in presence of HOBt·DCHA salt in solution as well as by the solid-phase methods is described. The coupling was found to be complete in 30 min and free from racemization. The synthesis of β-casomorphin by solid-phase protocol employing Fmoc-amino acid chloride/HOBt·DCHA in DMF-CH2Cl2 has also been outlined. The final peptide was obtained in 80% yield and was fully characterized. Copyright Taylor & Francis Group, LLC.
- Sureshbabu, Vommina V.,Sudarshan, Naremaddepalli S.,Chenna Krishna
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p. 2625 - 2637
(2008/12/22)
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- Microwave irradiated high-speed solution synthesis of peptide acids employing Fmoc-amino acid pentafluorophenyl esters as coupling agents
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A high-speed solution phase synthesis of peptide acids employing commercially available Fmoc-amino acid pentafluorophenyl esters as coupling agents has been demonstrated. The coupling has been found to be fast and completed in 30-45 sec. A simple work-up of the reaction mixture has resulted N-protected peptide acids in good yield. Utilizing the present method, the coupling of difficult sequences containing highly hindered α, α-dialkyl amino acids has also been demonstrated. Further, the synthesis of diastereomeric dipeptides, Fmoc-Phg-Phe-OMe and Fmoc-D-Phg-Phe-OMe revealed that the coupling is free from racemization.
- Suresh Babu, Vommina V.,Ramana Rao
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p. 2328 - 2332
(2007/10/03)
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- Synthesis of β-casomorphin employing Fmoc-amino acid chlorides and t-butyldimethylsilyloxy benzotriazole (TBDMS-OBt)
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Coupling of Fmoc-amino acid chlorides can be carried out using t-butyldimethylsilyloxy benzotriazole, the reaction being carried out in organic medium. No addition of base is required. The coupling is fast and racemization free. The workup and isolation of product are easy. Thus, the synthesis of β-casomorphin (Tyr-Pro-Phe-Pro-Gly) is accomplished.
- Tantry, Subramanyam J.,Mathad, Raveendra I.,Suresh Babu, Vommina V.
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p. 2104 - 2108
(2007/10/03)
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- Fmoc-amino acid azides in peptide synthesis
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Fmoc-amino acid azides can be prepared from the corresponding acid chlorides and sodium azide. All the compounds made have been obtained as solids in good yield and purity. They are found to be shelf stable at room temperature for longer periods. Their storage at room temperature does not lead to the formation of isocyanates. Employing them as coupling agents, the synthesis of a few dipeptides is described.
- Vasanthakumar, Ganga-Ramu,Ananda, Kuppanna,Suresh Babu, Vommina V
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p. 1733 - 1735
(2007/10/03)
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- (Fluoren-9-ylmethoxy)carbonyl (Fmoc) amino acid azides: Synthesis, isolation, characterisation, stability and application to synthesis of peptides
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The synthesis of Fmoc amino acid azides starting from the corresponding protected amino acid and sodium azide (NaN3) by the mixed anhydride method using isobutoxycarbonyl chloride (IBC-Cl) or by the acid chloride method is described. Isolated as crystalli
- Babu, Vommina V. Suresh,Ananda, Kuppanna,Vasanthakumar, Ganga-Ramu
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p. 4328 - 4331
(2007/10/03)
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- Synthesis of peptides employing Fmoc-amino acid chlorides and commercial zinc dust
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Coupling of Fmoc-amino acid chlorides mediated by activated commercial zinc dust for the synthesis of peptides is described. The reaction is carried out in an organic medium. The necessity of using an inorganic base like NaHCO3/Na2CO
- Gopi, Hosahudya N.,Suresh Babu, Vommina V.
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p. 9769 - 9772
(2007/10/03)
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- Synthesis of peptides mediated by potassium salt of 1-hydroxy-7-azabenzotriazole
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The potassium salt of 1-hydroxy-7-azabenzotriazole can be used along with acid chlorides of 9-fluorenylmethyloxycarbonylamino acids as coupling agents in peptide bond formation.The acylation reactions are rapid and efficient and can be carried out in an organic medium.The yields as well as purity of the peptides are satisfactory.
- Gopi, H. N.,Babu, V. V. Suresh
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p. 394 - 396
(2007/10/03)
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- Synthesis of [Leu5]enkephalin using Fmoc-Amino Acid Chlorides/KOAt
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The coupling of Fmoc-amino acid chlorides can be mediated by the potassium salt of 1-hydroxy-7-azabenzotriazole. Thus the synthesis of [Leu5]enkephalin has been accomplished in good yield and purity.
- Gopi,Suresh Babu
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p. 511 - 513
(2007/10/03)
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- Acid chloride/KOBt as a coupling agent in peptide synthesis
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Acylation reactions using 9-fluorenylmethoxycarbonylamino acid chlorides as coupling agents in peptide bond formation in the solution phase, can be conveniently carried out in the presence of the potassium salt of 1-hydroxybenzotriazole in dichloromethane
- Sivanandaiah, K M,Babu, V V Suresh,Shankaramma, S C
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p. 379 - 380
(2007/10/02)
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