The Reactivity of Cyclic Acetals of Aldoses and Aldosides

Gelas, Jacques

doi:10.1016/s0065-2318(08)60205-x

Cited by 132 publications

(29 citation statements)

References 237 publications

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“…[33][34][35][36] We have reported the one-pot synthesis of peracetylated 2-azido-2-deoxy sugars from commercially available 2-amino-2-deoxy sugar hydrochlorides through a diazo transfer reaction from trifluoromethanesulfonyl azide, [37] and this method has now been used for the preparation of the glycosyl donors 15 and 17 as shown in Scheme 3. Thus, -glucosamine hydrochloride was converted [37] into the tetra-O-acetylated 2-azido-2-deoxy derivative 8 and further into thioglycoside 9, [38] which was then transformed using well-established chemistry [18,23,[39][40][41][42][43] into the trichloroacetimidates 15 and 17 via the intermediates 10-14, and 10, 11 and 16, respectively (Scheme 3).…”

Section: Resultsmentioning

confidence: 99%

Attempted Synthesis of Type-A Inositolphosphoglycan Mediators – Synthesis of a Pseudohexasaccharide Precursor

Martín‐Lomas¹,

Flores-Mosquera²,

Chiara³

2000

Eur. J. Org. Chem.

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A block synthesis approach to the inositol‐containing pseudohexasaccharide 1 is presented. The myo‐inositol building block 6 has been prepared using a key regioselective acylation through a boron‐tin exchange reaction and the 2‐azido‐2‐deoxy glycosyl donors 15 and 17 have been synthesized from D‐glucosamine using a diazo transfer reaction. The anomeric position of the mono‐ and disaccharide building blocks has been temporarily protected as phenyl thioglycoside and this function was then converted into the different leaving groups to perform the glycosylation reactions. Both trichloroacetimidates and fluorides have been used as glycosyl donors for the construction of the different glycosidic linkages. The protected pseudohexasaccharides 44, 48‐50, which are precursors of pseudohexasaccharide 1, have been efficiently prepared and fully characterized. Pseudohexasaccharide 1 contains the fundamental structural features which have been proposed for type A inositolphosphoglycans, which may be involved in the insulin‐signaling process.

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Section: Resultsmentioning

confidence: 99%

Attempted Synthesis of Type-A Inositolphosphoglycan Mediators – Synthesis of a Pseudohexasaccharide Precursor

Martín‐Lomas¹,

Flores-Mosquera²,

Chiara³

2000

Eur. J. Org. Chem.

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“…[18] Literature records relatively few reports dealing with unsaturated aldehydes (and the stereochemistry of the products has been reported by Z. Jedlinski et al [19,20] ). O-Furylidene derivatives of methyl d-hexopyranosides are valuable comonomers in the synthesis of biologically active polymers.…”

Section: Introductionmentioning

confidence: 99%

Condensation and Polycondensation of Terephthaldehyde with MethylD-Hexopyranosides

Maślińska-Solich¹

2001

Macromol. Biosci.

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The condensation and polycondensations of terephthaldehyde (1) and methyl D‐hexopyranosides (gluco‐, galacto‐ and mannopyranoside) are described. Methyl α‐D‐glucopyranoside and methyl α‐D‐galactopyranoside react with 1 to give mono‐5 a and 6 a and diacetals 5 b and 6 b. Their structures were confirmed by NMR and IR spectroscopy. The polycondensation of methyl α‐D‐mannopyranoside (4) with 1 was studied in various solvents within the temperature range of 80–140°C. Regardless of the conversion or the initial comonomer feed ratios the composition of polycondensates depended on the reaction conditions leading to the formation of materials with diverse solubilities, molecular weights and optical properties. The regioselective polycondensation of 1 and 4 was examined by the 1H NMR spectroscopy of polymer 7. In the case of five‐membered cyclic acetal units, mixtures of the endo‐H and exo‐H dioxolan‐2‐yl system diastereomers are formed. Experimental examples of functionalization via ester units in polymer molecules 8 are described and the efficiency of the reaction routes and procedures are evaluated. The molecular weight was estimated by size‐exclusion chromatography (SEC) measurements before and after the functionalization.

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“…[32,33] The most commonly used conditions for acid hydrolysis are reflux in 80% aqueous AcOH, [34] stirring with 90% aqueous CF 3 CO 2 H acid in CH 2 Cl 2 at room temperature, [35] and reaction with 1% I 2 in CH 3 OH (w/v) at room temperature or at reflux. [36] Unfortunately, none of these methods work efficiently for the hydrolysis of the diasteroisomeric mixture 6a and 6b.…”

Section: H Al-mughaid and T B Grindley 2570mentioning

confidence: 99%