Glucopyranoside 4-deoxy-4- -, synthesis

Our initial studies were directed towards the synthesis and characterization of phenylboronate esters derived from methyl 6-deoxy-/ -D-allopyranoside, methyl a-L-rhamnopyranoside, methyl -L-fucopyranoside, and methyl 6-deoxy-/ -D-glucopyranoside. Previous work (14) in this laboratory indicated that the reaction of triphenylboroxole and methyl... 

Organic synthesis 28 [OS 28] Transgalactosylation of p-nitrophenyl-2-acetamide-2-deoxy-y D-glucopyranoside... 

The glycals are easily converted into the 1,2-dihalo-derivatives, which in principle can act as glycosyl donors. However, these derivatives have not found wide application in glycoside synthesis, mainly because of the low facial selectivity in the initial addition of the electrophilic species [143-145]. In an example of a successful application, 2-deoxy-2-bromo-a-D-glucopyranosyl bromide [146] has been shown to give predominantly the 2-deoxy-P-D-glucopyranosides in silver-triflate-promoted reactions with alcohols. 

Inverse type hetero-Diels-Alder reactions between p-acyloxy-a-phenylthio substituted a, p-unsaturated cabonyl compounds as 1-oxa-1,3-dienes, enol ethers, a-alkoxy acrylates, and styrenes, respectively, as hetero-dienophiles result in an efficient one step synthesis of highly functionalized 3,4-dihydro-2H-pyrans (hex-4-enopyranosides). These compounds are diastereospecifically transformed into deoxy and amino-deoxy sugars such as the antibiotic ramulosin, in pyridines having a variety of electron donating substituents, in the important 3-deoxy-2-gly-culosonates, in precursors for macrolide synthesis, and in C.-aryl-glucopyranosides. 

Stoicheiometric RuOyCCl was also used to oxidise several furanoses, partially acylated glycosides and l,4 3,6-dianhydrohexitols [317] pyranosides to pyrano-siduloses [313] methyl 2,3,6-tri-O-benzoyl-a-D-glucopyranoside and its C-4 epimer to the a-D-xy/o-hexapyranosid-4-ulose (Table 2.3) [317], and methyl 2,3,6-trideoxy-a-D-e 7f/tro-hexapyranoside to the -a-D-,g/yceri9-hexa-pyranosid-4-ulose, an intermediate in the synthesis of forosamine [318], It was also used to oxidise benzyl 6-deoxy-2,3-0-isopropylidene-a-L-mannopyranoside to the a-L-/yxo-hexapyranosid-4-ulose [319] and for oxidation of isolated secondary alcohol functions, e.g. in the conversion of l,6-anhydro-2,3-0-isopropylidene-P-D-man-nopyranose to the-P-D-/yxo-hexa-pyranos-4-ulose mannopyranose (Fig. 2.16, Table 2.3 [20, 320, 324]). 

SYNTHESIS OF BENZYL-4,6-O-lSOPROPYLlDENE-a-D-GLUCOPYRANOSIDE, 2-DEOXY-2-[[(2-HYDROXY-3,5-Dl-7erf-BUTYLPHENYL)METHYLENE]1M1NE]... 

J. Defaye, H. Driguez, B. Henrissat, I. Gelas, and E. Bar-Guilloux, Asymmetric acetalation of a-a-trehalose synthesis of a-D-galactopyranosyl and 6-deoxy-6-fluoro-ot-D-glucopyranosyl-a-D-glucopyranoside, Carbohydr. Res. 63 41 (1978). 

P. Sarda, A. Olesker, and G. Lukacs, Synthesis of methyl 2-C-acetamidomethyl-2-deoxy-oi-i>-glucopyranoside and its manno isomer, Carbohydr. Res. 229 161 (1992). 

In Section III, Danishefsky s methodology is illustrated by the synthesis of the basic compound 2,3-dihydro-4//-pyran-4-one, and 1-menthyl 2,3,6-tri-0-acetyl-4-deoxy-L-glucopyranoside. In this last example, high enantiomeric purity was achieved owing to the matched interaction between the catalyst [(+)-Eu(hfc)3] and the diene containing a chiral (1-menthyl) moiety. 

It has been reported that some simple, synthetic glycollpids, such as II-fatty acylated 2-amino-2-deoxy-D-glucose derivatives, exhibit potent immunostimulatory activities (5). We first examined a facile preparation of N-fatty acylated 2-amino-2-deoxy-D-glucopyranosides, which would be key intermediates for the synthesis of lipid A and its analogs (Figure 2). For this purpose, the one-step glycosylation catalyzed by ferric chloride (6, 7) was employed. 

Figure 2. Preparation of N-fatty acylated 2-antino-2-deoxy-D-glucopyranosides as intermediates for the synthesis of lipid A and its analogs.

Synthesis of 2-Amino-2-deoxy-/ -D-glucopyranosides. Properties and Use of 2-Deoxy-2-phthalimidoglycosyl Halides, R. U. Lemieux, T. Takeda, and B. Y. Chung, Amer. Chem. Soc. Symp. Series, 39 (1976) pp. 90-115. 

E. Walker, P. Roussel, R. W. Jeanloz, and V. N. Reinhold, The synthesis of methyl 2-acetamido-3,6-anhydro-2-deoxy-o -D-glucopyranoside and derivatives, Carbohydr. Res., 35 (1974) 270-279. 

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