- Preparation of dicarboxylate analogues of Cerulenin
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We have proposed and synthesized several new structural classes of Cerulenin analogues, which have potential as inhibitors of both fatty acid and polyketide synthase multi-enzyme complexes. These analogues contain cis epoxides bearing flanking carboxylate groups. Our syntheses have been designed to allow access to a wide range of fatty acid and polyketide-like side chains from readily available starting materials in convergent fashion in just four to five steps. In total, ~40 potential analogues have been prepared and characterized, covering all the structural sub-classes proposed, the majority of which constitute novel functional groupings.
- Moseley, Jonathan D.,Staunton, James
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p. 819 - 830
(2007/10/03)
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- Synthesis of an optically active 4-acetoxyazetidinone intermediate for penems and carbapenems
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The synthesis of the novel (3R,4R)-4-acetoxy-3[(1S)-1-t-butyldimethylsilyloxymethyl-1-((1S)-1-ph nylethylaminocarbonyl)]azetidin-2-one, a valuable key intermediate for penems and carbapenems bearing a 6-hydroxyacetamide side chain, and its diastereomer 1b
- Habich,Hartwig,Born
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p. 487 - 494
(2007/10/02)
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- A stereocontrolled approach to electrophilic epoxides
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Lithium t-butyl hydroperoxide (easily generated by addition of an alkyl-lithium to anhydrous t-butyl hydroperoxide in THF solution) is a powerful reagent for the epoxidation of electrophilic alkenes at -20 to 0 °C under full stereocontrol. Thus αβ-unsaturated esters, sulphones, sulphoximines, and amides are readily epoxidised with complete regio- and stereo-specificity and with considerable chiroselectivity (20-100%) when appropriate chiral auxiliaries such as menthyl, 8-phenylmenthyl, or a camphor-sulphonamide derivative are used. Asymmetric αβ-unsaturated sulphoximines undergo epoxidation with 100% diastereoselectivity. The only exceptions to stereocontrol noted are heavily substituted maleate esters such as di-t-butyl maleate. The αβ-epoxy amides are shown to be valuable sources of the corresponding epoxy ketones by treatment with an organolithium, allowing a stereo- and chemoselective entry in high yield to these useful intermediates.
- Meth-Cohn, Otto,Moore, Clive,Taljaard, Heinrich C.
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p. 2663 - 2674
(2007/10/02)
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- SYNTHESIS OF A NEW CARBAPENEM WITH A 6-METHYL HYDROXYACETATE SIDE CHAIN
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The synthesis of the 2-(4-pyridinylthio)-carbapen-2-em-3-carboxylic acid 1b, bearing a 6-methyl hydroxyacetate side chain, is decribed.
- Haebich, Dieter,Hartwig, Wolfgang
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p. 781 - 784
(2007/10/02)
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