Carbohydrate derivs., synthesi

N-nitrozo derivatives of N-glycosylureas attract attention to them not only as perspective antitumour preparations also as compounds with high reactional ability on the bases of which new methods of the carbohydrate derivative synthesis can be developed. 

H. Ito, Y. Motoki, T. Taguchi. and Y. Hanzawa, Zirconium mediated, highly diastereoselective ring contraction of carbohydrate derivatives Synthesis of highly functionalized, enantiomerically pure carbocycles, J. Am. Chem. Soc. 775 8835 (1993). 

Ito, H. et al. Zirconium-Mediated, Highly Diastereoselective Ring Contraction of Carbohydrate Derivatives Synthesis of Highly Functionalized, Enantiomerically Pure Carbocycles. 4.1 1993 [128]... 

Additionally, in a carbohydrate-derived synthesis of the oxahydrindene portion of the avermectins, a Swem oxidation was performed on the alcohol (35), demonstrating further the range of functionality that can be accommodated under these conditions. ... 

Barradas JS, Errea MI et al (2011) Imidazo[2,l-b]thiazole carbohydrate derivatives synthesis and antiviral activity against Junin virus, agent of argentine hemorrhagic fever. Eur J Med Chem 46 259-264... 

Lee D, Taylor MS (2012) Catalyst-controlled regioselective reactions of carbohydrate derivatives. Synthesis 44 3421... 

A low stereoselection is also reported for an Ugi reaction which is the central step in the total synthesis of the antibiotic ( + )-furanomycin80. The carbohydrate-derived intermediate, formed from the following acetal and (+ )-a-methyIbenzylamine, reacts with benzoic acid and tert-butyl isocyanide to deliver the precursor 2 of the antibiotic and its diastcreomer 3 in equal amounts80. 

The Oxidation of Some Carbohydrate Derivatives using Acetic Anhydride - Methyl Sulphoxide Mixtures and the Pfitzner-Moffat Reagent. Facile Synthesis of 3-Acetamido-3-deoxy-D-glucose and 3-Amino-3-deoxy-D-xylose, J. S. Brimacombe, J. G. H. Bryan, A. Husain, M. Stacey, and M. S. 

The synthesis in Scheme 13.44 is also based on a carbohydrate-derived starting material. It controlled the stereochemistry at C(2) by means of the stereoselectivity of the Ireland-Claisen rearrangement in Step A (see Section 6.4.2.3). The ester enolate was formed under conditions in which the T -enolate is expected to predominate. Heating the resulting silyl enol ether gave a 9 1 preference for the expected stereoisomer. The... 

R. Kaufman and R. S. Sidhu, Synthesis of aryl cluster glycosides by cyclotri-merization of 2-propynyl carbohydrate derivatives, J. Org. Chem., 47 (1982) 4941 1947. 

Several studies dealt with the synthesis of enantiomerically pure nitronates (5) (46, 48, 50, 68). These products were isolated by sophisticated chromatographic technique. Carbohydrate derivatives are mainly used as sources of asymmetric induction. 

Synthesis of a Carbohydrate-Derived Hydroxamic Acid Inhibitor of LpxC. 200... 

The observation of a stereoconvergent cyclization by Roy et al. [18], as shown in the third example, is of special interest from a synthetic point of view because it exploits the configurational lability of radicals in a favorable manner. The other examples, i. e. Nugent and RajanBabu s cyclization of a carbohydrate-derived epoxide [5d] and Clive s quinane synthesis [19], amply demonstrate the usefulness of the titanocene-initiated epoxide opening. 

Stereoselective intramolecular oxymercuration of carbohydrate derivatives was proposed as the key reaction for efficient preparation of mono- and dihydroxylated unsymmetrical bis-tetrahydrofuran skeletons present in naturally occurring biologically active acetogenins. The trans- and. mz-selective intramolecular oxymercurations were explored in an enantioselective synthesis of the bis-tetrahydrofuran skeleton of mucoxin (Fig. 57).73... 

Synthesis from carbohydrate derived 2-deoxy lactones. Routes to C-l glycals from 2-deoxy sugar pyranolactones have been described. The general strategy is outlined in Scheme 9. 

The scope of this cycloaddition reaction was very promising. Subsequently, removal of the CC-double bond and stereoselective functionalizations at positions 4 and 5 (carbohydrate numbering) was investigated for the synthesis of carbohydrates and related natural products, to provide C-3 branched carbohydrate derivatives (or C-4 heteroatom substituted derivatives after carbon/he-teroatom exchange reactions). However, the desired hydrogenation of such systems with various hydrogen donors has mainly resulted in low yields and/or side reactions due to the inherent stability of the formal CC-double bond (12., 15). ... 

Preparations of the "naked sugars" and their application to the synthesis of carbohydrate derivatives and other natural products are presented below. 

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