Glucose, acetic anhydride reaction

The above method for preparing glucose oxime is the modification of that of Jacobi1 developed by Wohl,2 who first converted the oxime into the pentaacetyl glucononitrile by means of acetic anhydride. The latter reaction was later employed for the same purpose by Zemplen and Kiss.3... 

One of the consequences of forming a cyclic hemi-acetal or hemiketal is that the nucleophilic hydroxyl adds to the carbonyl group and forms a new hydroxyl. This new group is susceptible to many normal chemical reactions of hydroxyls, e.g. esterification, and this type of reaction effectively freezes the carbohydrate into one anomeric form, since the ringopening and equilibration can now no longer take place. Consider esterification of glucose with acetic anhydride (see Section 7.9.1). P-o-Glucose will be... 

Preparation of nitrile acetates from oximes with sodium acetate and acetic anhydride. Pentaacetyl-v-glucononitrile. If only the nitrile is needed, isolation of the oxime can be avoided. One hundred grams of anhydijous n-glucose was dissolved in 50 ml. of warm water, and maintaining the temperature at 60°, a solution of 28 g. of hydro-xylamine in 700 ml. of ethanol was added sufficiently slowly that no precipitation took place. After one hour at 65°, the reaction mixture was concentrated under reduced pressure to a thick sirup. The residue was mixed with absolute ethanol, the ethanol evaporated and the operation repeated in order to eliminate all water. One hundred and twenty grams of anhydrous sodium acetate and 700 ml. of acetic anhydride were added to the sirup, and the mixture was slowly and cautiously warmed in a water bath to 95°. It was advisable to agitate the flask continuously and to watch the... 

Monosaccharides contain a number of alcoholic hydroxyl groups, and thus can react with acid anhydrides to yield corresponding esters. For example, when glucose is treated with acetic anhydride and pyridine, it forms a pentaacetate. The ester functions in glucopyranose pentaacetate undergo the typical ester reactions. 

Treatment of 15 with l,5-diazabicyclo[5.4.0]undec-5-ene (DBU) in benzene resulted in /3-elimination, but under these conditions, the liberated 2,3,4,6-tetra-O-methyl-D-glucose was further degraded, probably with formation of 3-deoxy-2,4,6-tri-0-methyl-D-erc/fhro-hex-2-enopyranose. In order to prevent this degradation, the reaction of 15 with DBU was carried out in the presence of acetic anhydride. The reaction mixture gave, after chromatography on silica gel, methyl (methyl 4-deoxy-2,3-di-0-methyl-a-L-threo-hex-4-enopyranosid)uron-ate (65) and a mixture of the 1-acetates of 2,3,4,6-tetra-O-methyl-a- and -/3-D-glucose (66). 

Conversion of sugar phenylhydrazones into olefinic azo-sugars on treatment with acetic anhydride and pyridine was shown by Wolfrom and co-workers (28) (The acetylated forms of the acyclic phenylhydrazones of D-glucose, D-mannose, and D-galactose readily lose the elements of acetic acid to yield 1-phenylazo-frans-l-hexenetetrol tetraacetate when treated with warm aqueous ethanol (28, 30). It is assumed that atmospheric oxygen partakes in this elimination reaction.) This is a special case of base catalyzed -elimination reactions of the type proposed by Isbell in 1943 ( 31), involving consecutive electron displacement (which actu-... 

Another highly versatile building block derived from diacetone-glucose 54 is the 1,2-acetonide of 3-C-methyl-a-D-allose in its furanoid form 57, which has been utilized as the key compound in a convergent total synthesis of ACRL Toxin I (63). Its elaboration from 54 starts with a pyridinium dichromate / acetic anhydride oxidation (64), is followed by carbonyl olefination of the respective 3-ulose with methyl (triphenyl)phosphonium bromide and hydrogenation (— 55 56), and is completed by acid cleavage of the 5,6-isopropylidene group. This four-step process 54 -> 57, upon optimization of reaction conditions and workup procedure, allows an overall yield of 58 % (63), as compared to the 22 % obtained previously (65). 

Incidental reactions that have been reported include the preparation of derivatives of 5-(hydroxymethyl)-2-furaldehyde by reaction of D-fructose in acetic or propionic acid in the presence of the respective anhydride.158 The condensation of D-glucose with phenol has been effected in acetic acid in the presence of dry hydrogen chloride, prior to resinification,157 and the reaction of sucrose with thionyl chloride in acetic acid-acetic anhydride produced partially acetylated chlorodeoxysucroses.158 Sucrose has been condensed with maleic anhydride in acetic anhydride mixed with acetic acid or formic acid, to give solid products having an undetermined structure.159... 

In a 1-1. round-bottomed flask are placed 66 g. (0.33 mole) of glucose monohydrate (Note 1) and 302 g. of 95 per cent acetic anhydride (280 cc., 2.81 moles). To this mixture three small drops of concentrated sulfuric acid are added from a medicine dropper (Note 2). The glucose is kept in partial suspension by shaking the flask with a swirling motion the reaction starts almost immediately. If the temperature of the mixture approaches the boiling point, the flask is momentarily immersed in a pan of cold water. Within ten to fifteen minutes nearly all the glucose will have dissolved and the temperature of the reaction mixture will ha ve risen nearly to 100°. The flask is loosely stoppered and is healed on a steam bath for two hours. Then about 200 cc. of mixed acetic acid and acetic anhydride is removed by distillation under reduced pressure (Note 3). 

A novel approach to synthesize the glucose-based 3-acetyl-5-alkyl-2,3-dihy-dro-l,3,4-oxadiazoles with the assistance of microwave irradiation was developed by Wang et al. [42]. The reaction of a mixture of E/Z hydrazones (xLvii, xLviii) with acetic anhydride under microwave irradiation above 160 °C, to produce the target 1,3,4-oxadiazoles (xLix, L), which are a parr of isomers on the C-3 of furan ring. 

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