- Towards a total synthesis of ustiloxins A and B. Stereocontrolled synthesis of (2S,4S,6S)-4-hydroxy-5-phenylsulfinylnorvaline
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A short, stereocontrolled synthesis of (2S,4S,6S)-4-hydroxy-5-phenylsulfinylnorvaline (8), an unusual amino acid component of ustiloxins A and B, has been achieved. Stereoselective bromolactonisation of N-Boc-(S)-allylglycine (3) is followed by substitution of the bromide 4a with thiophenol to give the corresponding sulfide 5. Highly stereoselective oxidation of the sulfide 5 gives the corresponding sulfoxide 6a. Removal of the Boc group and lactone ring opening then complete the synthesis of the unusual amino acid.
- Hutton, Craig A.,White, Jonathan M.
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p. 1643 - 1646
(2007/10/03)
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- Synthetic Studies on Antifungal Cyclic Peptides, Echinocandins. Stereoselective Total Synthesis of Echinocandin D via a Novel Peptide Coupling
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Synthetic studies on the novel fungicidal oligopeptides, echinocandins (1b and 1c), are described.The constituent amino acids 5-8 were synthesized in a stereocontrolled manner from the chiral starting materials, 5a, 6a and 7a, respectively.The coupling of these amino acids was characterized by the use of unprotected amino acid as the C-terminal and 2-pyridyl thiol ester as the N-terminal, and the coupling was performed in the presence of 1-(trimethylsilyl)imidazole (TMSIm) or a catalytic amount of tert-amine to give C-terminal free dipeptides, 14 and 16a, respectively, which were converted to the pentapeptide 17a, a common intermediate for the synthesis of 1b and 1c.The synthesis of 1c was achieved by the cyclization of the hexapeptide 24b.
- Kurokawa, Natsuko,Ohfune, Yasufumi
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p. 6195 - 6222
(2007/10/02)
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- AN EFFICIENT ROUTE TO 1,3-AMINO HYDROXYL SYSTEM VIA ELECTROPHILIC LACTONIZATION OF 2-AMINO-4-PENTENOIC ACID DERIVATIVES. STEREOSELECTIVE SYNTHESIS OF (-)-BULGECININE
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Several γ-hydroxy-α-amino acid systems were prepared stereoselectively from 2-amino-4-pentenoic acid derivatives using electrophilic lactonization.This strategy was applied to the synthesis of a highly functionalized proline analogue, (-)-bulgecinine (4).
- Ohfune, Yasufumi,Hori, Keiko,Sakaitani, Masahiro
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p. 6079 - 6082
(2007/10/02)
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