- Staudinger/aza-Wittig reaction to access Nβ-protected amino alkyl isothiocyanates
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A unified approach to access Nβ-protected amino alkyl isothiocyanates using Nβ-protected amino alkyl azides through a general strategy of Staudinger/aza-Wittig reaction is described. The type of protocol used to access isothiocyanates depends on the availability of precursors and also, especially in the amino acid chemistry, on the behavior of other labile groups towards the reagents used in the protocols; fortunately, we were not concerned about both these factors as precursor-azides were prepared easily by standard protocols, and the present protocol can pave the way for accessing title compounds without affecting Boc, Cbz and Fmoc protecting groups, and benzyl and tertiary butyl groups in the side chains. The present strategy eliminates the need for the use of amines to obtain title compounds and thus, this method is step-economical; additional advantages include retention of chirality, convenient handling and easy purification. A few hitherto unreported compounds were also prepared, and all final compounds were completely characterized by IR, mass, optical rotation, and 1H and 13C NMR studies.
- Santhosh,Durgamma,Shekharappa,Sureshbabu, Vommina V.
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p. 4874 - 4880
(2018/07/15)
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- Hydrodehalogenation of alkyl iodides with base-mediated hydrogenation and catalytic transfer hydrogenation: Application to the asymmetric synthesis of N-protected α-methylamines
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We report a very mild synthesis of N-protected α-methylamines from the corresponding amino acids. Carboxyl groups of amino acids are reduced to iodomethyl groups via hydroxymethyl intermediates. Reductive deiodination to methyl groups is achieved by hydrogenation or catalytic transfer hydrogenation under alkaline conditions. Basic hydrodehalogenation is selective for the iodomethyl group over hydrogenolysis-labile protecting groups, such as benzyloxycarbonyl, benzyl ester, benzyl ether, and 9-fluorenyloxymethyl, thus allowing the conversion of virtually any protected amino acid into the corresponding N-protected α-methylamine.
- Mandal, Pijus K.,Birtwistle, J. Sanderson,McMurray, John S.
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p. 8422 - 8427
(2015/03/18)
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- Synthesis of Nα-Z protected amino alkyl triazole acids and their application to neo-glycopeptides synthesis
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The synthesis of triazole linked glycopeptides employing 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) mediated coupling of Z-protected triazole acids with glycosyl amines and amino acid esters is described. The coupling proceeded smoothly at room temperat
- Madhu, Chilakapati,Panguluri, Nageswara Rao,Sureshbabu, Vommina V.
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p. 858 - 864
(2014/08/05)
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- A simple synthesis of N β-Fmoc/Z-amino alkyl thiols and their use in the synthesis of N β-Fmoc/Z-amino alkyl sulfonic acids
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A simple and efficient protocol for the synthesis of Nβ- Fmoc/Z-amino alkyl thiols is described. The approach uses sodium pyrosulfite-mediated hydrolysis of isothiouronium salts resulting from the reaction between N-protected aminoalkyl iodides and thiourea. N-Protected taurines were prepared through performic acid oxidation of the thiols and the products were further utilized for the synthesis of dipeptidosulfonamides. Georg Thieme Verlag Stuttgart - New York.
- Sureshbabu,Vishwanatha,Vasantha
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p. 1037 - 1042
(2010/07/06)
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- A simple approach for the synthesis of new classes of dithiocarbamate-linked peptidomimetics
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An efficient protocol for the synthesis of a new series of dithiocarbamate-linked peptidomimetics is described. The in situ generated dithiocarbamic acid intermediate formed by the reaction of an amino acid ester and carbon disulfide in the presence of triethylamine was treated with N-protected amino alkyl iodide to afford title compounds 3a-g in good to moderate yields. The synthesis of N-Fmoc-protected tripeptidomimetics 4a-e containing two dithiocarbamate linkages is also described. The protocol was further extended to synthesize N,N′-orthogonally protected dithiocarbamate-linked dipeptidomimetics 7a-c as well. The mild reaction conditions and non-toxic reagents are the advantages of the present method.
- Hemantha, Hosahalli P.,Sureshbabu, Vommina V.
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body text
p. 7062 - 7066
(2010/03/01)
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- Synthesis of enantiopure N-and C-protected homo-β-amino acids by direct homologation of α-amino acids
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Enantiopure N-and/or C-protected homo-β-amino acids are prepared readily and in good yields from N-protected α-amino acids with the same side chain, via reduction of the carboxyl function and conversion of the resulting N-protected β-amino alcohol into the corresponding β-amino iodide and then β-amino cyanide. The key step of this strategy is represented by the synthesis of the enantiopure N-protected β-amino iodides 2 and 3 that are smoothly obtained from the parent amino alcohols 1 by polymer bound triarylphosphine-I2 complex in anhydrous dichloromethane.
- Caputo, Romualdo,Cassano, Ersilia,Longobardo, Luigi,Palumbo, Giovanni
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p. 12337 - 12350
(2007/10/02)
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- Chiral N-Protected β-Iodoamines from α-Aminoacids: a General Synthesis
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N-Protected D- or L-β-iodoamines (as 2), which are useful intermediates for the preparation of chiral β-aminoacids, are obtained smoothly from β-aminols (as 1) in two steps and high yields.
- Caputo, Romualdo,Cassano, Ersilia,Longobardo, Luigi,Palumbo, Giovanni
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p. 167 - 168
(2007/10/02)
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- Studies of HIV-1 protease inhibitors. I. Incorporation of a reduced peptide, simple aminoalcohol, and statine analog at the scissile site of substrate sequences
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Inhibitors of the protease of human immunodeficiency virus type-1 (HIV-1) were designed and synthesized. A reduced peptide, simple aminoalcohol, and statine analog, 4-amino-3-hydroxy-5-phenylpentanoic acid (AHPPA), were inserted at the scissile site of su
- Sakurai,Sugano,Handa,Komai,Yagi,Nishigaki,Yabe
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p. 1369 - 1377
(2007/10/02)
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