Abstract: Ionic liquids and cellulose ester compositions and processes and apparatus for producing ionic liquids and cellulose esters. Cellulose esters can be produced by dissolving cellulose in carboxylated ionic liquids and thereafter contacting the cellulose solution with at least one acylating reagent. Cellulose esters produced via the present invention can comprise ester groups that originate from the carboxylated ionic liquid and/or the acylating reagent.

Abstract: The present invention provides a means to concentrate, dry and formulate biomaterials such as polysaccharides, gums and related biopolymers, and microorganisms such as cells, spores, and the like from dilute solutions using spent germ and other oil bearing residues. In addition, the spent germ can serve as a carrier for such biomaterials. The sorbed materials are useful in animal feeds.

Abstract: A method for the chlorination of a sucrose-6-acylate to produce a 4,1?,6?-trichloro-4,1?,6?-trideoxy-galactosucrose-?-acylate wherein said method comprises: (i) reacting the sucrose-6-acylate with a chlorinating agent in a reaction vehicle comprising a tertiary amide in order to chlorinate the 4, V and 6? positions of the sucrose-6-acylate; and (ii) quenching the product stream of (i) to produce a 4,1?,6?-trichloro-4,1?,6?-trideoxy-galactosucrose-6-acylate; wherein before said quenching, a portion of the tertiary amide is removed.

Abstract: The present invention provides a water-soluble modified HA practically used as a drug carrier and a production method thereof. The present invention provides: a water-soluble modified hyaluronic acid, the residence time in blood of which is elongated to a practical level, which is produced by introducing a substituent into the carboxy group of the glucuronic acid of hyaluronic acid or a derivative thereof, via an amide bond, at a lower limit of an introduction ratio of 5 mole % or more, using a BOP condensing agent in an aprotic polar solvent; and a production method thereof. Moreover, by cross-linking the modified hyaluronic acid, the present invention provides a hyaluronic acid gel capable of extremely long drug sustained-release even at the same cross-linking functional group introduction ratio as that of the conventionally known gel.

Abstract: A method of extracting starch from corn. The method comprises steeping ground corn in a mixture of ammonium hydroxide and water, for a period of between 45 minutes and 20 hours wherein the mixture has a pH level between about 11.3 and 11.4. This method provides the advantage of extracting starch from corn with higher yields in less time.

Abstract: A description is given of glyoxal-treated polysaccharide derivatives which, to decrease the unbound glyoxal, are treated with an aqueous solution of one or more water-soluble aluminium salts, or one or more water-soluble borates, or a combination of one or more water-soluble aluminium salts and one or more water-soluble borates, and, if appropriate, with suitable buffer substances to set the pH, and then dried. A description is likewise given of a process for decreasing the content of unbound glyoxal in glyoxal-treated polysaccharide derivatives.

Abstract: An allergen inactivating agent is provided which has no adverse effects on the human body and which does not cause problems such as color development.

Abstract: The present invention relates to a series of polyglycoside derivatives that are (a) polymeric (that is cross linked with hydroxypropyl linkages) and (b) contain additional functional groups including alkoxy, sulfate, sulfonate, quaternary and phosphate groups, and (c) sugars to increase water solubility and provide outstanding foaming agents and detergents that are naturally derived and readily biodegradable.

Abstract: The present invention provides a phosphoramidate compound having the structure (I) wherein X comprises a monosaccharide group comprising the structure (II) or (III) or a pharmaceutically acceptable salt, ester or salt of such ester. The present invention also provides processes for the production of (I) and uses thereof.

Abstract: The invention relates to novel transglycosylation products and their preparation. The transglycosylation products according to the invention are prepared from starch derivatives, such as esters or ethers of starch. The products are obtained by reacting a starch derivative with an alcohol in the presence of an acid catalyst. The forming product is separated by precipitation or by removing any unreacted alcohol by evaporation. In the products according to the invention the good properties of starch derivatives, such as the excellent water resistance of esters, are combined with the versatility of transglycoside products. The products can be used as adhesives, in which case they are formulated, for example as hot-melt adhesives, and as comonomers, prepolymers or macroinitiators in the preparation of polymers.

Abstract: A method of preparing 2-deoxy-L-ribose represented by the following formula I is disclosed. The preparation method includes the steps of: treating L-arabinose with an alcohol solvent in the presence of an acid to prepare 1-alkoxy-L-arabinopyranose; allowing the prepared 1-alkoxy-L-arabinopyranose to react with acyl chloride so as to prepare 1-alkoxy-2,3,4-triacyl-L-arabinopyranose; brominating the alkoxy group of the prepared 1-alkoxy-2,3,4-triacyl-L-arabinopyranose to prepare a 1-bromo-2,3,4-triacyl compound; allowing the prepared compound to react with zinc in the presence of ethyl acetate and an organic base so as to prepare glycal; treating the glycal with an alcohol solvent in the presence of an acid to prepare 1-alkoxy-2-deoxy-3,4-diacyl-L-ribopyranose; treating the prepared 1-alkoxy-2-deoxy-3,4-diacyl-L-ribopyranose with a base to prepare 1-alkoxy-2-deoxy-L-ribopyranose; and hydrolyzing the prepared 1-alkoxy-2-deoxy-L-ribopyranose in the presence of an acid catalyst.

Abstract: Compositions which inhibit corrosion and alter the physical properties of concrete (admixtures) are prepared from salt mixtures of hydroxycarboxylic acids, carboxylic acids, and nitric acid. The salt mixtures are prepared by neutralizing acid product mixtures from the oxidation of polyols using nitric acid and oxygen as the oxidizing agents. Nitric acid is removed from the hydroxycarboxylic acids by evaporation and diffusion dialysis.

Abstract: A starch-based biodegradable material composition includes: an enzyme-hydrolyzed starch; and a biodegradable polyester selected from at least one of an aliphatic polyester of polybutylene succinate and an aliphatic-aromatic copolyester. The enzyme-hydrolyzed starch is prepared by hydrolyzing a native starch using a starch-hydrolyzing enzyme. The starch-hydrolyzing enzyme has an activity unit ranging from 15000 to 40000.

Abstract: Methods are described for conversion of carbohydrate polymers in ionic liquids, including cellulose, that yield value-added chemicals including, e.g., glucose and 5-hydroxylmethylfurfural (HMF) at temperatures below 120° C. Catalyst compositions that include various mixed metal halides are described that are selective for specified products with yields, e.g., of up to about 56% in a single step process.

Abstract: This invention relates to a method of extracting crude polysaccharide by microwave-assisted from Artemisia sphaerocephala seed de-oiling dregs. In particular, the invention comprising: microwave-assisted extraction, enzymatic hydrolysis, dialysis et. al. It provides a technique whereby the polysaccharide can be extracted effectively, in a relatively short period of time (20-30 min) with respect to conventional extraction methods and allows for an enhanced extraction yield (more than 30%). Furthermore, the invention also allows for the extraction of material with less solvent consumption, good reproducibility, excellent solubility, energy conservation, environmental protection, and showed great potential for efficient sample preparation and large-scale industrial application in the near future. With great resource advantage of Artemisia sphaerocephala in China, the invention has bright perspectives in promoting local economic development.

Abstract: Disclosed is a method of detecting even a very small amount of a target substance by mixing a linker and a spacer at a suitable ratio and immobilizing the mixture on the surface of carbon nanotubes in a carbon nanotube-based biosensor. This method detects a specific substance at the level of femtomoles and lowers the detection limit of conventional carbon nanotube transistor sensors. Accordingly, the method detects even a very small amount of a target substance, and thus the carbon nanotube-based biosensor is a highly useful sensor which can be used either as a medical sensor for diagnosing diseases or as an environmental sensor.

Abstract: Granular sucralose-containing particles are produced by the methods of the invention, which involve coating sucralose from solution to form granules with this coated sucralose on an outer region thereof. The granules may incorporate agglomerated sucralose particles, with the solution-coated sucralose adding mass and generally resulting in a granule having a relatively smoothed and rounded. The granules have good flow properties, are low dusting, and resist caking. Methods of making the granules involve spraying an aqueous sucralose solution onto a fluidized bed of sucralose particles, followed by drying to form the granules.

Abstract: An apparatus for manufacturing gel particle according to an embodiment of the invention is an apparatus for manufacturing gel particle of a first liquid and a second liquid by delivering the droplets of the first liquid including a gel particle-forming material to the second liquid that becomes the gel particle through reactions, and includes: a container that contains the second liquid; a flow mechanism unit that makes the second liquid flow in a spiral manner in the container; a tank that contains the first liquid; and an ejection mechanism unit that is communicated with the tank and is provided with a nozzle plate having a plurality of nozzles formed in a disposition that is along an array direction in which the liquid droplets of the first liquid are ejected on the second liquid made to flow in a spiral manner.

Abstract: The present invention relates to a process of preparing hydroxyalkyl cellulose derivatives having improved enzymatic resistance. In particular, the present invention relates to a process of preparing hydroxyalkyl cellulose derivatives by reacting cellulose and ethylene oxide in the presence of alkali metal hydroxide, wherein the reaction between cellulose and ethylene oxide is performed in the presence of isopropyl alcohol azeotropic solvent in a horizontally agitated reactor, wherein the ethylene oxide is supplied via two steps, thus resulting in a two-step reaction, and the amount of alkali metal hydroxide remaining after the first reaction is controlled, thereby enabling to provide hydroxyalkyl cellulose derivatives having improved enzymatic resistance and turbidity and to remarkably decrease the solvent usage to have economical and environmental advantages.

Abstract: The present invention relates to a heparin fraction comprising constituents having molecular weights of from about 2,000 to about 4,000 daltons, wherein from about 1% to about 100% of hydroxyl residues of the constituents are oxidized. The present invention also relates to methods of inhibiting angiogenesis and treating an angiogenesis-mediated disorder in a subject by administering a heparin fraction comprising constituents having molecular weights of from about 2,000 to about 30,000 daltons, wherein from about 1% to about 100% of hydroxyl residues of the constituents are oxidized. Another aspect of the present invention relates to compositions including the heparin fractions of the present invention.

Abstract: It has been found that a limulus-positive glycolipid is present in xanthan gum derived from Xanthomonas, which has been commercially available and eaten for many years, and this was purified, and it has been found that this limulus-positive glycolipid has an immunopotentiation effect. A method for safely and inexpensively producing the limulus-positive glycolipid containing an immunopotentiator at high concentrations is provided. The method for producing the limulus-positive glycolipid of the present invention comprises extracting the limulus-positive glycolipid from xanthan gum. A limulus-positive glycolipid composition containing the limulus-positive glycolipid can be used for various applications such as pharmaceuticals, pharmaceuticals for animals, quasi drugs, cosmetics, foods, functional foods, feedstuff and bath agents.

Abstract: A photocrosslinked polysaccharide pseudo-sponge exhibiting a low swelling property and a high degradation ability in vivo while retaining a suitable strength. The polysaccharide pseudo-sponge is produced by a crosslinking reaction of a photoreactive polysaccharide obtained by introducing a photoroactive group into a polysaccharide, and exhibits a low swelling property and a blue dextran-low dyaffinity.

Abstract: Partially desulphated glycosaminoglycan derivatives are described, particularly heparin, and more particularly a compound of formula (I) where the U, R and R1 groups have the meanings indicated in the description. These glycosaminoglycan derivatives have antiangiogenic and heparanase-inhibiting activity and are devoid of anticoagulant activity.

Abstract: Provided are methods for the solubilization of cellulose into soluble sugars without the need for high temperatures, high pressures, strong acid solutions, and/or added water. The produced sugars can be fermented into ethanol. In one embodiment, the method comprises contacting a cellulose-containing material with a solid acid material and agitating the cellulose-containing material and the solid acid material for a time sufficient to produce an aqueous solution comprising a quantity of soluble sugars.

Abstract: An objective of the present invention is to provide a glycan releasing method which can be applied to construction of a system for automation of glycan analysis, and particularly a glycan releasing method capable of analyzing an O-linked glycan. The objective could be achieved as a result of finding that the pH is lowered by using an ammonium salt or ammonium ion in the absence of concentrated aqueous ammonia, not using concentrated aqueous ammonia, thus drastically avoiding an undesired side reaction such as a peeling reaction or the like.

Abstract: A cyclic carbonyl monomer has the formula (7): wherein at least one W? or Wa group comprises a protected glycoside; each Z independently represents O, S, NH or NW?; n is an integer from 0 to 6 wherein when n is 0, carbons labeled 4 and 6 are linked together by a single bond; each W? and Wa group independently represents a hydrogen, a halide, an alkyl group comprising 1 to 20 carbons, an ester group comprising 1 to 20 carbons, an amide group, an aryl group comprising 1 to 20 carbons, an alkoxy group comprising 1 to 20 carbons, or a foregoing W? or Wa group substituted with a protected glycoside; and each W? group independently represents an alkyl group comprising 1 to 20 carbons, an aryl group comprising 1 to 20 carbons, or a foregoing W? group substituted with a protected glycoside.

Abstract: A method for the manufacture of at least one sorbent having at least two different groups, which are capable of binding, for the selective binding of a substrate, characterized in that it comprises the steps (i) to (ii): (i) determining at least two groups capable of binding a sorbent from a synthetic or natural first substrate, (ii) respectively applying at least two different groups capable of binding a second synthetic or natural substrate to one respective carrier, thereby forming at least one sorbent, whereby the groups are the same groups of step (i) or are groups that are complementary thereto, and the second substrate of step (ii) is the same or different from the first substrate according to step (i), and whereby the groups are determined such that the contributions of the Gibbs energies of the individual groups to the non-covalent bond with the second substrate yield a negative value of the Gibbs energy ?G, such that a binding strengthening occurs that results in an improved separation selectivity

Abstract: The present invention relates to a process for the production of second generation biofuels and/or sugar based chemicals—for example ethanol, butanol etc—and/or materials—for example plastics, single cell proteins etc.—together with sulfonated lignin from lignocellulosic biomass, in particular from lignocellulosic biomass comprising, among others, annual plants, agricultural waste, or wood. In particular, the present invention relates to a process for the production of sugar based chemicals, biofuels or materials together with sulfonated lignin from lignocellulosic biomass comprising the pretreatment of a lignocellulosic biomass in a sulfite cooking step.

Abstract: The invention relates to C-glycose compounds of formula (I) where: S? is a monosaccharide radical or a polysaccharide radical derived from a monosaccharide or polysaccharide S; R is a linear or branched alkyl radical; and Z is an ethylenyl CH?CR1(R2) or an acetylenyl C?CR3 radical. The invention also relates to a method for preparing C-glycoside compounds of formula (III), characterised in that the method consists of a step of reacting a sugar (S), in an aqueous solvent or in the absence of a solvent and in the presence of an organic or mineral base (B), with a phosphonate of formula (II) according to the following reaction pattern: Formulas (II), (III).

Abstract: The device and method of this invention provides a means to increase anhydrosugars yield during pyrolysis of biomass. This increase is achieved by injection of a liquid or gas into the vapor stream of any pyrolysis reactor prior to the reactor condensers. A second novel feature of our technology is the utilization of sonication, microwave excitation or shear mixing of the biomass to increase the acid catalyst rate for demineralization or removal of hemicellulose prior to pyrolysis. The increased reactivity of these treatments reduces reaction time as well as the required amount of catalyst to less than half of that otherwise required. A fractional condensation system employed by our pyrolysis reactor is also a novel element of our technology. This system condenses bio-oil pyrolysis vapors to various desired fractions by differential temperature manipulation of individual condensers comprising a condenser chain.

Abstract: A dihydroxyphenyl cross-linked macromolecular network is provided that is useful in artificial tissue and tissue engineering applications, particularly to provide a synthetic macromolecular network for a wide variety of tissue types. In particular, artificial or synthetic cartilage, vocal cord material, vitreous material, soft tissue material and mitral valve material are described. In an embodiment, the network is composed of tyramine-substituted and cross-linked hyaluronan molecules, wherein cross-linking is achieved via peroxidase-mediated dityramine-linkages that can be performed in vivo. The dityramine bonds provide a stable, coherent hyaluronan-based hydrogel with desired physical properties.

Abstract: A polysaccharide comprising galactose, glucose, rhamnose, and pyruvic acid as constituents, wherein the galactose, glucose, and rhamnose are contained in a molar ratio of 4:2:1, and the pyruvic acid is contained in an amount of 4 to 7 wt %. The polysaccharide can be obtained by culturing Bifidobacterium longum JBL05 (NITE BP-82) under anaerobic conditions.

Abstract: The present application discloses a molded article, and a process for preparing a molded article consisting essentially of (i) high molecular weight linear ?-1,4-glucan and (ii) low molecular weight linear ?-1,4-glucan, wherein the process comprises the step of: adding the low molecular weight linear ?-1,4-glucan to a solution comprising the high molecular weight linear ?-1,4-glucan to gel the solution, wherein the low molecular weight linear ?-1,4-glucan has a degree of polymerization of greater than or equal to 180 and less than 620, and has a molecular weight distribution of not greater than 1.25 and, the high molecular weight linear ?-1,4-glucan has a degree of polymerization of greater than or equal to 620 and less than 37000, and has a molecular weight distribution of not greater than 1.25.

Abstract: The invention relates to a method for preparing 1,6:2,3-dianhydro-â-D-mannopyranose and is characterized in that it includes a step of cyclizing the compound C, where R is an alykyl group and R? is an activating agent, in an alcohol/alcoholate mixture under anhydrous conditions.

Abstract: The subject of the present invention is a novel method for preparing a composition of internal dehydration product of a hydrogenated sugar, comprising: a) a step of distilling a medium containing the said internal dehydration product in order to obtain a distillate enriched with this product, b) optionally, at least one subsequent step of purifying the distillate thus obtained, c) a subsequent step of bringing the distillate obtained during step a), and then optionally subjected to step b), into contact with an agent capable of improving the stability of the internal dehydration product predominantly contained in the distillate, the said agent not being in gaseous form, d) optionally, a subsequent step of shaping the resulting composition of internal dehydration product of a hydrogenated sugar. This method makes it possible in particular to obtain a stable isosorbide composition, characterized by its purity and/or its content of certain stabilizing or nonstabilizing species.

Abstract: The present invention provides methods for making porous crosslinked polysaccharide hydrogel coated structures. The methods include impregnating a porous substrate with a room temperature stable aqueous polysaccharide solution containing, water, a polysaccharide having a concentration in the aqueous solution from about 0.1% to about 20%, a gel-inhibiting agent having a concentration in the aqueous solution from about 18 to about 54%, and an anionic fluorosurfactant having a concentration in the aqueous solution from about 0.001% to about 10% by total weight of the aqueous solution. Followed by evaporating the water from the polysaccharide coating; and exposing the dehydrated polysaccharide coating to a gelling agent form a porous polysaccharide hydrogel coated substrate. The hydrogel coated substrate is exposed to a crosslinking agent to form a porous crosslinked polysaccharide hydrogel coated substrate.

Abstract: An object of the present invention is to provide means for preparing a monosaccharide by efficiently hydrolyzing a polysaccharide. In particular, in a method that uses a homogeneous acid catalyst to obtain a monosaccharide from a polysaccharide, a low energy, low cost catalytic separation method is provided, and in addition, a method for obtaining high reaction selectivity is provided. In addition, provided is a homogeneous acid catalyst separation method that separates a homogeneous acid catalyst from a homogeneous acid catalyst-containing solution with high efficiency and realizes a high homogeneous acid catalyst recovery ratio at low energy costs, and that is applicable to a variety of reaction systems.

Abstract: The present invention includes as an active ingredient at least one biosurfactant, in particular mannosyl alditol lipid (such as MEL and MML) or triacylated mannosyl alditol lipid. This allows providing an activator and anti-aging agent that is excellent in activating and anti-aging effects on cells and that is safe enough to be used for a long time, and also providing cosmetics, quasi-drugs, drugs, and drinks and foods including the activator and the anti-aging agent as active ingredients. Further, the present invention provides MEL whose mannosyl erythritol skeleton in a molecular structure is 1-O-?-D-mannopyranosyl-meso-erythritol and a method for producing the MEL with use of a microorganism.

Abstract: This invention relates to modified starches having an elevated content of phosphate and an elevated content of amylose.

Abstract: Carrier polymer particles comprising organic polymer particles having a particle diameter of 0.1 to 20 micrometers and a saccharide with which the surface of the organic polymer particles is covered, the organic polymer particles and the saccharide being chemically bonded.

Abstract: A method for modifying fibers is provided, which method comprises dispersing in water or a dilute alkali aqueous solution under shear a cellulose ether having such a low degree of substitution that a molar degree of substitution with an alkyl group and/or a hydoxyalkyl group ranges from 0.05 to 1.3, applying the resulting dispersion to fibers, and drying the applied fibers.

Abstract: A method for preparing hexose derivatives comprises the steps of providing a silylated hexose, treating the silylated hexose with a first carbonyl compound in the presence of a catalyst to form an ketalized hexose, treating the ketalized hexose with a second carbonyl compound followed by treating with a first reductant to form an etherized hexose, and converting the etherized hexose into a target hexose derivative, which can be 2-alcohol hexose, 3-alcohol hexose, 4-alcohol hexose, or a 6-alcohol hexose. In particular, the present invention can prepare the hexose derivatives with highly regioselective scheme to protect individual hydroxyls of monosaccharide units and install an orthogonal protecting group pattern in a one-pot manner.

Abstract: Methods for obtaining Tamaritt and Tamaritt-Intermediate based materials are implemented through a secondary chemical reactor providing a second chemical reaction conducted with at least two reactants. The first reactant is Tamaritt and the second is an inorganic, or organic, or bio-molecular reagent, or their combination. Tamaritt is produced in a primary chemical reactor, modulating chemical reactions, preferably using a plasma device, and producing certain byproducts. A solid organic dye is dissolved in water producing a solution placed into the primary reactor, wherein the temperature and pressure are predeterminedly adjusted. The byproducts are injected into the solution, thereby commencing a first chemical reaction conducted until it finally results in obtaining Tamaritt. Tamaritt-Intermediate byproducts, being bond-altering catalyst-reagents, are obtained at a certain stage of the process.

Abstract: The present invention relates to a method for the selective oxidation of a carbohydrate in the presence of a gold catalyst which includes nanodispersed gold particles on a metal oxide support, to a method for the selective oxidation of an oligosaccharide in the presence of a gold catalyst which comprises nanodispersed gold particles on a carbon or metal oxide support, and to the aldonic acid oxidation products prepared by use of these methods.

Abstract: An object of the present invention is to provide a method for commercially manufacturing acrolein in a large flow rate by making supercritical water and an acid interact with glycerin, wherein by efficiently mixing high-concentration glycerin and supercritical water with each other, the method is made capable of making the synthesis stably proceed with a high yield while the occlusion and abrasion of the pipes and devices due to the generation of by-products are being suppressed.

Abstract: Disclosed is a method for producing polyalcohols in the form of sugar alcohols from the group comprising sorbitol and mannitol and other optional C2 to C6 polyols. According to said method, a monosaccharide, disaccharide, oligosaccharide, or polysaccharide containing at least one glucose unit and/or at least one fructose unit is continuously reacted with hydrogen at an elevated temperature and at a great pressure in an aqueous phase in the presence of a hydrogenating catalyst based on ruthenium or ruthenium oxide so as to obtain the inventive polyalcohols. The minimum temperature is set at 100° C. while the minimum pressure is set at 150 bar and the maximum dwell time of the reactants during catalytic hydrogenation is set at 600 s.

Abstract: A stable and high-purity protected pseudouridine in crystal form is provided represented by the following structural formula: wherein M represents a trityl group or a derivative thereof, which is a useful material for producing an RNA oligomer or a similar substance. A method for producing the crystalline protected pseudouridine is also provided, which method includes crystallizing a protected pseudouridine from a solution containing the protected pseudouridine, by use of an ester solvent and/or an alcoholic solvent. The method, which does not need a silica gel column treatment, can be performed in a simple manner, does not impose a load on the environment, and realizes low-cost production of a target crystalline protected pseudouridine.

Abstract: Alkali and alkali-earth metal salts of polysaccharides derived from heparin, their method of preparation and the pharmaceutical compositions containing them.

Abstract: The invention relates to a method for depolymerizing materials containing carbohydrates comprising the following steps: (a) treating a material containing carbohydrates with an inorganic catalyst in order to release defined monomeric or oligomeric building blocks from the material containing the carbohydrates; and (b) separating the defined monomeric or oligomeric building blocks produced in step (a) from the rest of the carbohydrate-containing material. Preferably, the inorganic catalyst used in step (a) comprises tectosilicates, phyilosilicates or hydrotalcites and more preferably zeolites or bentonites. The carbohydrate-containing material further comprises preferably LCB and the defined monomeric or oligomeric building blocks are preferably glucoses, xyloses, arabinoses and oligomers thereof. Other aspects of the invention refer to the use of solution promoters in combination with the inorganic catalyst.

Abstract: The invention provides novel synthetic intermediates and processes that can be used to prepare compounds of formula (I), wherein R1 has any of the values described herein and R2 is a nucleoside sugar group.