- Synthesis of regio- and stereoselectively deuterium-labelled derivatives of l-glutamate semialdehyde for studies on carbapenem biosynthesis
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l-Glutamate semialdehyde (l-GSA) is an intermediate in biosynthetic pathways including those leading to the carbapenem antibiotics. We describe studies on asymmetric deuteration or hydrogenation of appropriate didehydro-amino acid precursors for the stereoselective synthesis of C-2- and/or C-3-[2H]-labelled l-GSA suitable for use in mechanistic studies. Regioselective deuterium incorporation into the 5-position of l-GSA was achieved using a labelled form of the Schwartz reagent (Cp2Zr 2HCl). 4,4-Dideuterated and fully backbone deuterated l-GSAs were prepared. The application of the labelled l-GSA derivatives to biosynthetic studies was exemplified by the chemo-enzymatic preparation of selectively deuterated trans-carboxymethylprolines using two different carboxymethylproline synthases (CarB and ThnE), enzymes that catalyse early steps in the biosynthesis of two carbapenems: (5R)-carbapenem-3-carboxylate and thienamycin, respectively. The Royal Society of Chemistry 2009.
- Ducho, Christian,Hamed, Refaat B.,Batchelar, Edward T.,Sorensen, John L.,Odell, Barbara,Schofield, Christopher J.
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supporting information; experimental part
p. 2770 - 2779
(2009/09/07)
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- Copper-catalysed asymmetric 1,4-addition of organozinc compounds to linear aliphatic enones using 2,2′-dihydroxy 3,3′-dithioether derivatives of 1,1′-binaphthalene
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Directed ortho dilithiation of bis(diethylcarbamate) or bis(MOM)-protected (Sa)-1,1,′-bi(2-naphthol) followed by treatment with R2S2 [R = Me, Ph (X-ray structure)] or Me2Se2 cleanly affords the 3,3′ derivatives; the free naphthols are produced on deprotection. In the case of the bis(MOM) series, but not that of the bis(carbamates), some racemisation occurs. The ligand 2,2′-dihydroxy-3,3′-dimethylthio-1,1′-binaphthalene shows optimal performance in the addition of ZnEt2 to linear aliphatic enones (E)-R1C(O)CH=CHR2. Variation of the steric demands of R1 and R2 generates catalytic results consistent with binding of a zinc-based Lewis acid anti to the ene function and with the reactive conformation being s-cis. With enones containing the functions R2 = (CH2)nCH(OAlkyl)2 (n = 0-2), the ZnEt2 addition products undergo base-promoted cyclisation.
- Boerner, Christoph,Dennis, Michael R.,Sinn, Ekkehard,Woodward, Simon
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p. 2435 - 2446
(2007/10/03)
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- Synthesis of Malonaldehyde Monoacetals
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The synthesis of a series of malonaldehyde manoacetals is described.Selective hydrolysis or transacetalisation of 1,1,3,3-tetramethoxypropane and its analogues was proved to be a very general technique.
- Shi-Qi, Peng,Winterfeldt, Ekkehard
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p. 1045 - 1047
(2007/10/02)
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- Novel pesticides, preparation and use
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The specification describes and claims methods of controlling acarine pests by application of a compound of Formula (I), methods of controlling arthropod pests by application of a compound of Formula (IA), compounds of Formula (IA) per se, pesticidal compositions comprising a compound of Formula (IA), and processes for preparing a compound of Formula (IA).
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- Synthesis and Use of 7-Substituted Norbornadienes for the Preparation of Prostaglandins and Prostanoids
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Syntheses of 7-substituted norbornadienes from 7-t-butoxy- and 7-halogeno-norbornadienes are described.Rearrangement of the products in the presence of peracetic acid gives bicyclic aldehydes (2) in equilibrium with enol ethers (3) which are hydrolysed to hydroxycyclopentenylacetaldehydes (4), and converted into key intermediates for the synthesis of prostaglandins and their analogues.Syntheses of prostaglandin J analogues with n-hexyl and phenyl groups replacing the ο-side-chain are described.
- Baxter, Anthony D.,Binns, Falmai,Javed, Tariq,Roberts, Stanley M.,Sadler, Peter,et al.
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p. 889 - 900
(2007/10/02)
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