- Studies on the substrate specificity of a GDP-mannose pyrophosphorylase from Salmonella enterica
-
A series of methoxy and deoxy derivatives of mannopyranose-1-phosphate (Manp-1P) were chemically synthesized, and their ability to be converted into the corresponding guanosine diphosphate mannopyranose (GDP-Manp) analogues by a pyrophosphorylase (GDP-ManPP) from Salmonella enterica was studied. Evaluation of methoxy analogues demonstrated that GDP-ManPP is intolerant of bulky substituents at the C-2, C-3, and C-4 positions, in turn suggesting that these positions are buried inside the enzyme active site. Additionally, both the 6-methoxy and 6-deoxy Manp-1P derivatives are good or moderate substrates for GDP-ManPP, thus indicating that the C-6 hydroxy group of the Manp-1P substrate is not required for binding to the enzyme. When taken into consideration with other previously published work, it appears that this enzyme has potential utility for the chemoenzymatic synthesis of GDP-Manp analogues, which are useful probes for studying enzymes that employ this sugar nucleotide as a substrate.
- Zou, Lu,Zheng, Ruixiang Blake,Lowary, Todd L.
-
p. 1219 - 1226
(2012/09/21)
-
- Single diastereomers of polyhydroxylated 9-Oxa-1-azabicyclo[4.2.1]nonanes from intramolecular 1,3-dipolar cycloaddition of ω-unsaturated nitrones
-
8-Benzyloxymethyl-3,4,5-tribenzoyloxy-9-oxa-1-azabicyclo[4.2.1]nonane has been prepared as the single diastereoisomer 8 from an intramolecular 1,3-dipolar cycloaddition involving 2-(benzyloxy)acetaldehyde and ω-unsaturated hydroxylamine 7 derived from methyl α-D-glucopyranoside. The analogous 8-methoxycarbonyl 9-oxa-1-azabicyclo[4.2.1]nonane was afforded in a similar manner, from methyl D-galactopyranoside and methyl glyoxylate, as a 3:1 mixture of diastereoisomers 15 and 16. When conducted in achiral ionic liquid 17 this ratio increased to 8:1, and in chiral ionic liquid 18, compound 15 was formed exclusively.
- Padar, Petra,Bokros, Attila,Paragi, Gabor,Forgo, Peter,Kele, Zoltan,Howarth, Nicola M.,Kovacs, Lajos
-
p. 8669 - 8672
(2007/10/03)
-
- Palladium chloride mediated rearrangement of 6-deoxyhex-5-enopyranosides into cyclohexanones
-
PdCl2 was found to mediate the Ferrier rearrangement of broad range of substrates catalytically in neutral conditions. In this reaction, the stereoselectivity of newly formed chiral center was controlled by the hydroxyl protective groups on the starting sugar moiety and was rationally explained by the consideration of chair like conformations.
- Iimori, Takamasa,Takahashi, Hideyo,Ikegami, Shiro
-
p. 649 - 652
(2007/10/02)
-
- Metal-Graphite Reagents in Carbohydrate Chemistry. 8. The Scope and Limitations of the Use of Zinc/Silver-Graphite in the Synthesis of Carbohydrate-Derived Substituted Hex-5-enals and Pent-4-enals
-
The compatibility of different organic functional groups with the use of the zinc/silver-graphite reagent was investigated, utilizing 23 6-bromo-6-deoxy- or 6-deoxy-6-iodohexopyranosides and 5-deoxy-5-iodopentofuranose derivatives.These compounds possessed O-acetyl, O-benzoyl, O-methyl-, or O-p-tolylsulfonyl, O-benzyl, O-methyl, O-isopropylidene, epoxy, acetamido deoxy, azido deoxy, chloro deoxy, and deoxy fluoro groups and included a mono and a dideoxy derivative.Reductive dealkoxyhalogenation of these compounds gave, in most instances, a single product, a hex-5- or pent-4-enal, which could be considered a precursor for carbocyclization reactions.Iodides reacted faster than bromides, and pyranose derivatives reacted faster and more cleanly than furanose derivatives.The kinetic or thermodynamic stability of the product enal was found to be structure-dependent.Reduction of the carbon-halogen bond was one of the few side reactions observed.A mechanism for the reductive ring cleavage is proposed.
- Fuerstner, Alois,Jumbam, Denis,Teslic, Judith,Weidmann, Hans
-
p. 2213 - 2217
(2007/10/02)
-
- CHAIN ELONGATION BY USE OF AN IRON CARBONYL REAGENT: A FACILE SYNTHESIS OF 6-DEOXYHEPTOSIDURONIC ACIDS
-
A method of chain elongation at the nonreducing terminal of 6-deoxy-6-halo- and 6-O-tosyl-hexopyranosides, to give methyl (methyl 6-deoxyheptopyranosid)uronates was developed on the basis of organo-iron chemistry.Thus, methyl 2,3,4-tri-O-acetyl-6-O-p-toly
- Baer, Hans H.,Hanna, Hanna R.
-
p. 169 - 184
(2007/10/02)
-