Branched-chain sugars. Part 17. A synthesis of L-rubranitrose (2,3,6-trideoxy-3-C-methyl-4-O-methyl-3-nitro-L-xylo-hexopyranose)

Brimacombe, J. S.; Rahman, Khandker M. M.

doi:10.1039/p19850001067

Cited by 19 publications

(3 citation statements)

References 12 publications

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“…Alkoxyamine 11 was prepared using a similar strategy. Triethylnitromethane ( 8 ) was readily prepared via a Ritter reaction from the corresponding tertiary alcohol . Nitrone formation was achieved with activated Zn and nitroalkane 8 in the presence of benzaldehyde (→ 9 , 53%).…”

Section: Resultsmentioning

confidence: 99%

“…(1,1-Diethylpropyl)[phenylmethylidene]ammoniumolate ( 9 ). 3-Ethyl-3-nitropentane ( 8 ) (1.22 g, 8.41 mmol), benzaldehyde (1.34 g, 12.6 mmol), and NH 4 Cl (0.50 g, 9.25 mmol) were dissolved in a mixture of Et 2 O (5 mL) and H 2 O (10 mL) and cooled to 0 °C. Zinc powder (2.20 g, 33.6 mmol) was added in small portions over a period of 1 h, and the reaction mixture was vigorously stirred at room temperature for 19 h. The heterogeneous mixture was filtered through a sintered glass filter, and the residue was washed with Et 2 O.…”

Section: Methodsmentioning

confidence: 99%

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New Sterically Hindered Nitroxides for the Living Free Radical Polymerization: X-ray Structure of an α-H-Bearing Nitroxide

et al. 2003

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The synthesis of three new sterically hindered Hawker−Braslau type alkoxyamines for the nitroxide-mediated living radical polymerization is described. Efficient polymerizations can be performed at 105 °C. With alkoxyamine 11 controlled polymerization of n-butyl acrylate and styrene is possible even at 90 °C. AA and AB diblock copolymers can be prepared in a controlled manner using alkoxyamine 11. Kinetic EPR experiments for the determination of the C−O bond activation energies of the new alkoxyamines are described. Furthermore, 1H NMR alkoxyamine decomposition studies are presented. These kinetic experiments are used for the discussion of the polymerization results. Furthermore, the X-ray structure of a Hawker-Braslau type nitroxide is presented. X-ray data and ESR data are used to explain the high stability of these nitroxides.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

New Sterically Hindered Nitroxides for the Living Free Radical Polymerization: X-ray Structure of an α-H-Bearing Nitroxide

et al. 2003

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“…20 It was later revised to be a D-sugar when compared to chemically synthesized L- and D-rubranitrose. 21,22 The L-isomer of rubranitrose is also called L-evernitrose ( 16 ) as it was originally identified in the structure of everninomycins ( 17 ) from Micromonospora carbonaceae . 23–25 The last example, L-decilonitrose ( 18 ) was found in decilorubicin ( 19 ), an anthracycline antibiotic from Streptomyces virginiae .…”

Section: Sugars Containing Oxidized Aminesmentioning

confidence: 99%

The biosynthesis of nitrogen-, sulfur-, and high-carbon chain-containing sugars

2013

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Carbohydrates serve many structural and functional roles in biology. While the majority of monosaccharides are characterized by the chemical composition: (CH2O)n, modifications including deoxygenation, C-alkylation, amination, O- and N-methylation, which are characteristic of many sugar appendages of secondary metabolites, are not uncommon. Interestingly, some sugar molecules are formed via modifications including amine oxidation, sulfur incorporation, and “high-carbon” chain attachment. Most of these unusual sugars have been identified over the past several decades as components of microbially produced natural products, although a few high-carbon sugars are also found in the lipooligosaccharides of the outer cell walls of Gram-negative bacteria. Despite their broad distribution in nature, these sugars are considered “rare” due to their relative scarcity. The biosynthetic steps that underlie their formation continue to perplex researchers to this day and many questions regarding key transformations remain unanswered. This review will focus on our current understanding of the biosynthesis of unusual sugars bearing oxidized amine substituents, thio-functional groups, and high-carbon chains.

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The Oxidation of Alcohols by Modified Oxochromium( VI )–Amine Reagents

Luzzio

1998

Organic Reactions

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The development of oxochromium(VI)‐amine reagents as oxidants in organic synthesis has evolved since the early studies of Sisler which described the use of adducts of heterocyclic nitrogen bases and chromium(VI) oxide. The later work of Sarrett and coworkers in steroid synthesis soon established the utility of chromium(VI) oxide‐pyridine adducts as the first selective oxochromium(VI)‐amine reagents. Several modifications of the Sarrett oxidation followed. The present concern with the toxicity and environmental implications of oxochromium(VI) has provided encouragement for the study and use of catalytic oxochromium reagents in conjunction with stoichiometric co‐oxidants such as peroxides. Such technology is welcome, particularly when applied to the large‐scale preparations found in industry where the disposal of byproducts is a constant problem. Modified oxochromium(VI)‐amine reagents on polymer supports have been prepared and examined with the objective of providing a regenerable reagent system which is serviceable on a practical scale. A significant improvement in routine oxidations utilizing PCC and PDC entails the addition of adsorbents such as Celite®, alumina, silica gel, molecular sieves, or zeolites. The distinct advantages associated with the use of adsorbents in oxochromium(VI)‐amine‐mediated oxidations are discussed. The importance of buffers and desiccants in oxochromium(VI) oxidations is discussed. Virtually any number of oxochromium(VI)‐amine reagents may be prepared by varying the amine ligand and/or acid species associated with oxochromium(VI), and many of these compounds have been tested using simple substrate alcohols for oxidation to carbonyl compounds. The search for a milder and more efficient oxidant than the Sarrett‐type oxochromium(VI) reagent systems as well as the nonchromium oxidants based on dimethyl sulfoxide or dimethyl sulfide led to an examination of the utility of pyridinium chlorochromate (PCC) in selective oxidations of alcohols. PCC was superior in terms of ease of preparation, shelf stability and economy. Since the introduction of PCC in 1975 the reagent has become a commercially available “textbook” compound and is usually the reagent of choice for routine large and small scale oxidations of alcohols to carbonyl compounds. Unlike the oxochromium(VI)‐pyridine adducts, PCC is an acid salt, and its properties have proven advantageous in a number of tandem oxidative reactions such as oxidative transpositions and oxidative cationic cyclizations. Several reviews address the versatility of PCC and its extension to many different types of oxidative conversions in single and multistep organic syntheses. While PCC was gaining widespread use, the utility of pyridinium dichromate (PDC) in solvents such as dimethylformamide (DMF) and dichloromethane was reported. PDC/DMF was useful for oxidizing allylic alcohols to the corresponding, α,β‐unsaturated carbonyl compounds and non‐conjugated aldehydes and primary alcohols to the corresponding carboxylic acids. The utilization of beyond the simple oxidation of alcohols, and it is now employed for various transformations. Many other types of substituted pyridines, nitrogen heterocycles and amines form chromates, dichromates, and chlorochromates which allow many different types of oxidative processes for a wide range of substrate molecules. This chapter surveys the many applications of oxochromium(VI) complexes in oxidative conversions of alcohols to carbonyl compounds. Alternative reagent systems based on modifications involving ligands, buffering agents, or adsorbents, as well as nonchromium(VI) oxidants are discussed. A variety of substrates have been included in the Tables so as to guide the synthetic chemist in selecting reagents and conditions that will be optimal for a given transformation. Oxidative conversions of alcohols through transpositions and cationic cyclizations giving carbonyl compounds as endproducts are included.

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Branched-chain sugars. Part 17. A synthesis of L-rubranitrose (2,3,6-trideoxy-3-C-methyl-4-O-methyl-3-nitro-L-xylo-hexopyranose)

Cited by 19 publications

References 12 publications

New Sterically Hindered Nitroxides for the Living Free Radical Polymerization: X-ray Structure of an α-H-Bearing Nitroxide

New Sterically Hindered Nitroxides for the Living Free Radical Polymerization: X-ray Structure of an α-H-Bearing Nitroxide

The biosynthesis of nitrogen-, sulfur-, and high-carbon chain-containing sugars

The Oxidation of Alcohols by Modified Oxochromium( VI )–Amine Reagents

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