- Synthesis of dysideaproline e using organocatalysis
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(S)-4,4-Dichloro-3-methylbutanoic acid was prepared in 51% overall yield from commercially available starting materials using an organocatalytic transfer hydrogenation to 4,4-dichloro-3-methylbut-2-enal in the key step. The (S)-dichloro acid was used as an intermediate in the first total synthesis of dysideaproline E and a diastereomer confirming the structure of the natural product.
- Owusu-Ansah, Ernest,Durow, Amanda C.,Harding, John R.,Jordan, Angela C.,O'Connell, Susan J.,Willis, Christine L.
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body text
p. 265 - 272
(2011/02/24)
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- Effective methods for the synthesis of N-methyl β-amino acids from all twenty common α-amino acids using 1,3-oxazolidin-5-ones and 1,3-oxazinan-6-ones
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N-Methyl β-amino acids are generally required for application in the synthesis of potentially bioactive modified peptides and other oligomers. Previous work highlighted the reductive cleavage of 1,3-oxazolidin-5-ones to synthesise N-methyl α-amino acids. Starting from α-amino acids, two approaches were used to prepare the corresponding N-methyl β-amino acids. First, α-amino acids were converted to N-methyl α-amino acids by the so-called '1,3-oxazolidin-5-one strategy', and these were then homologated by the Arndt-Eistert procedure to afford N-protected N-methyl β-amino acids derived from the 20 common α-amino acids. These compounds were prepared in yields of 23-57% (relative to N-methyl α-amino acid). In a second approach, twelve N-protected α-amino acids could be directly homologated by the Arndt-Eistert procedure, and the resulting β-amino acids were converted to the 1,3-oxazinan-6-ones in 30-45% yield. Finally, reductive cleavage afforded the desired N-methyl β-amino acids in 41-63% yield. One sterically congested β-amino acid, 3-methyl-3-aminobutanoic acid, did give a high yield (95%) of the 1,3-oxazinan-6-one (65), and subsequent reductive cleavage gave the corresponding AIBN-derived N-methyl β-amino acid 61 in 71% yield (Scheme 2). Thus, our protocols allow the ready preparation of all N-methyl β-amino acids derived from the 20 proteinogenic α-amino acids.
- Hughes, Andrew B.,Sleebs, Brad E.
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p. 2611 - 2637
(2007/10/03)
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- Total synthesis of the chlorinated marine natural product dysamide B
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Two approaches to the synthesis of (2S,4S)-5,5-dichloroleucine are compared, and the parent amino acid was used in the first total synthesis of the polychlorinaled marine natural product, dysamide B. A key step was the lead tetraacetate-mediated decarboxylation of an α,α-dichloro acid in the presence of 1,4-cyclohexadiene to generate the dichloromethyl group.
- Durow, Amanda C.,Long, G. Cliona,O'Connell, Susan J.,Willis, Christine L.
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p. 5401 - 5404
(2007/10/03)
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- Boronic ester and acid compounds, synthesis and uses
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Disclosed herein are boronic ester and acid compounds, their synthesis and uses. More specifically, disclosed herein is a method for reducing the rate of degradation of proteins in an animal comprising contacting cells of the animal with certain boronic ester and acid compounds.
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- A simple and rapid protocol for N-methyl-α-amino acids
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A two step strategy for optically pure N-Protected-N-methyl-α-amino acids starting from N-protected-α-amino acids via reductive cleavage of oxazolidinones using NaCNBH3/TMSCl is described.
- Reddy, G. Vidyasagar,Iyengar
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p. 299 - 300
(2007/10/03)
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- Synthesis and biological activities of [N-MeLeu5]- and [N-MePhe5]- didemnin B
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Based on information from X-ray, NMR, and SAR data, the N,O-diMeTyr5 unit of didemnin B was believed to be important for biological activity. To determine the importance of aromaticity and the role of the methoxy group in this unit, two analogs
- Pfizenmayer, Amy J.,Ramanjulu, Joshi M.,Vera, Matthew D.,Ding, Xiaobin,Xiao, Dong,Chen, Wei-Chuan,Joullie, Madeleine M.
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p. 313 - 334
(2007/10/03)
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- BORONIC ESTER AND ACID COMPOUNDS
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Disclosed herein is a method for reducing the rate of degradation of proteins in an animal comprising contacting cells of the animal with certain boronic ester and acid compounds. Also disclosed herein are novel boronic ester and acid compounds, their synthesis and uses.
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- Dolastatins. 26. Synthesis and stereochemistry of dolastatin 11
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The first synthesis of dolastatin 11, a potent antineoplastic agent from the sea hare Dolabella auricularia, confirmed the proposed structure and established the last configuration in this natural product and in dolastatin 12, majusculamide C, and 57-norm
- Bates, Robert B.,Brusoe, Kennard G.,Burns, Jennifer J.,Caldera, Sriyani,Cui, Wei,Gangwar, Sanjeev,Gramme, Michelle R.,McClure, Kelly J.,Rouen, Gregory P.,Schadow, Heiko,Stessman, Chad C.,Taylor, Stuart R.,Vu, Vicky H.,Yarick, Gayle V.,Zhang, Jianxing,Pettit, George R.,Bontems, Roger
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p. 2111 - 2113
(2007/10/03)
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- Aldehyde derivatives and their use as calpain inhibitors
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Aldehyde derivatives with a specific calpain inhibiting activity and a platelet-aggregation inhibiting effect with formula (I) or formula (II): wherein R1 represents an aromatic hydrocarbon group, a heterocyclic group, or a group of-X-R3 in which X represents O,-S(O)m-(m = 0, 1, or 2), and R3 represents an aromatic hydrocarbon group, a heterocyclic group, or an alkyl group; Z represents R?-Y-or R?O-CH(R?)-in which Y represents a 3-to 7-membered nitrogen-containing saturated heterocyclic group, or a single cyclic saturated hydrocarbon group, R? represents an alkyl group, an alkenyl group, an alkynyl group, an acyl group, a sulfonyl group, an alkoxycarbonyl group, a carbamoyl group, or a thiocarbamoyl group, R? represents hydrogen, an alkyl group, or an aromatic hydrocarbon group, and R? represents an acyl group, a carbamoyl group, a thiocarbamoyl group, or an alkyl group; and n is an integer of 1 to 5. wherein R?, R?, R?, and R1? are defined in the specification.
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- SYNTHESIS OF TWO LINEAR OCTAPEPTIDE FRAGMENTS OF CYCLOSPORIN BY STEPWISE AND FRAGMENT CONDENSATION STRATEGIES
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The octapeptide Z-(Me)Leu-Val-(Me)Leu-Ala-D-Ala-(Me)Leu-(Me)Leu-(Me)Val-O(t-Bu) was prepared by stepwise elongation starting from H-(Me)Val-O(t-Bu).Diphenylphosphinic mixed anhydrides were preferentially used throughout as they gave high yields of optical
- Galpin, I. J.,Mohammed, A. K. A.,Patel, A.,Priestley, G.
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p. 1763 - 1772
(2007/10/02)
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- Peptides and processes for the manufacture thereof
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The somatostatin-analogous peptides according to the invention of the general formula STR1 in which Bmp represents the desaminocysteine radical X represents Asn or His, trp represents D-Trp that may be substituted in the benzene ring by a halogen atom, and Y represents the radical of a secondary α-amino acid having a maximum of 8 carbon atoms and the corresponding peptide amides and also acid addition salts and complexes thereof are distinguished by strong insulin-antagonistic and glucagon-antagonistic effects and are therefore therapeutically acceptable, preferably in the form of pharmaceutical preparations, in similar indications to those of somatostatin, especially also as antidiabetics. The compounds are manufactured by conventional processes of peptide synthesis, especially by liberation from corresponding protected intermediates and by the formation of the cystine disulphide bridge by means of oxidation.
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- Acyl derivatives
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Peptide derivatives provided by the present invention are compounds of the general formula STR1 wherein R1 represents a hydrogen atom or the methyl or hydroxymethyl group or a mono-, di- or trihalomethyl mgroup; R2 represents the cha
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