A-Acetobromoglucose

D-glucopyranosyl esters of abscisic acid and /3-ionylideneacetic acid (120) have been prepared by treatment of the acid with a-acetobromoglucose in the presence of triethylamine/ Two papers " describe a new synthesis of y-ionone (64) in which the key intermediate (121) is prepared from y-cyclocitral (122) and acetone in the presence of BU2BSO3CH2CF3. 

Experiment 5.109 2.3.4.6-TETRA-O-ACETYL-oc-d-GLUCOPYRANOSYL BROMIDE (a-Acetobromoglucose)... 

Treatment of the intermediate (7), prepared4 from 2,4-diethoxy-pyrimidine and a-acetobromoglucose, with ethanolic ammonia afforded4 cytosine-D-glucoside (8). 

Attempts to use basic reaction components other than 2,4-dialkoxy-pyrimidines met with varied success. Thus, the early attempt of Hilbert30 to react a-acetobromoglucose with 4-amino-2-methoxy-pyrimidine (19) failed. On the other hand, when 4-ethoxy-2(lI/)-pyrimidinone (20) or l-methyl-4-methoxy-2(li/)-pyrimidinone (21) was condensed with 2,3,5-tri-O-benzoyl-D-ribofuranosyl chloride, moderate yields were obtained of 3-/9-D-ribofuranosyluracil (22) and its 1-methyl derivative (23), respectively.31... 

The reaction 21 of a-acetobromoglucose with 2-ethylthio-4-ethoxy-6-methylpyrimidine (24) resulted in the formation of both anomeric 0-4-glycosyl derivatives (the 2-ethylthio function remained intact). 

Instead of 2,4-dialkopyrimidines, some other alkoxy heterocyclics capable of lactam-lactim tautomerism were used, e.g., 2-ethoxy-pyridine42,43 (36), 4-ethoxypyridine44 (37), and 3,6-dibenzyloxy-pyridazine45 (38). Treatment of a-acetobromoglucose with 36 gave... 

Similarly, treatment of 2-trimethylsilyloxypyridine (46) with a-acetobromoglucose and silver perchlorate in nitromethane at 20° yielded l-(2,3,4,6-tetra-0-acetyl-D-glucopyranosyl)-2-pyridone (47) as the sole product.46 47 On the other hand, 2-ethoxypyridine (vide supra) gave a mixture of 0- and V-glycosyl derivatives.42,43... 

In the preparation of 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosy bromide (a-acetobromoglucose), hydrogen bromide is generated either as described above or by dropping liquid bromine into boiling tetralin. ... 

TaxicatFn. 3,5-Dimethoxyphenol glucoside. CH-HjqOj mol Wt 316.30. C 53.16%, H 6,37%. O 40.477c. Isojn from leaves of Tax us baccata L Taxaceae Lefebvre, Arch. Pharm. 245, 486 (1907) Merz, Preuss, ibid. 279, 134 (1941). Structure and synthesis from 3,5-dimethoxyphenol and a-acetobromoglucose Merz, Preuss, foe. cit. 

Chloromethyl methyl or ethyl ether, for instance, and KSCN in light petroleum form methoxymethyl or ethoxymethyl isothiocyanate, respectively,856 and 2,3,4,6-tetra-O-acetyl-a-D-glucopyranosyl isothiocyanate is obtained from a-acetobromoglucose and AgSCN in toluene.857... 

Pteridineglycosides. 4-Dimethylamino-7(8H)-pteridinone dissolved in refluxing xylene, freshly prepared Ag-carbonate added, part of the xylene distilled off to remove traces of water, a-acetobromoglucose added, stirring and refluxing continued 1.5 hrs. 4-dimethylamino-7-(2,3,4,6-tetraacetyl-/ -D-glucopyranosyl-oxy)pteridine. Y 79%. Also pteridine-N-8-glycosides s. W. Pfleiderer and D. Soil, J. Heterocyclic Chem. 1, 23 (1964). 

Montero et al. employed the TPP/DIAD and TBP/ADDP redox couples to prepare the Mitsunobu betaine as a base under mild conditions Deprotonation of the doubly activated sulfonamide 239 then produced die reactive anion that was alkylated in situ by a variety of alkyl bromides (benzyl, allyl, a-acetobromoglucose, etc.). Attempts to prepare the alkylated products via more traditional mineral base conditions using sodium or potassium carbonate gave much inferior yields of around 10%. The TBP/ADDP couple, as shown below, gave better yields in the alkylation chemistry generally, the modest alkylation yields are around 40-60%. 

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