Glycosides aryl

A combination of Cp nCX —A CXC) (where = cyclopentadienyl) effectively promotes the Friedel-Crafts coupling of glycosyl fluorides with aromatic compounds, such as trimethoxyben2ene or methoxynaphthalenes. The derived C-aryl glycosides are potent antitumor agents (39). 

The glycal epoxide method turned out to be useful for the construction of complex 2-branched [3-aryl glycosides, which are salient features of the potent antibiotic vancomycin [75a]. Glycal epoxide glycosylation with sodium salts of indoles pro-... 

Stereoselective inverse-demand hetero (4 + 2) cycloadditions. A Chiral Template for C-Aryl Glycoside Synthesis. Chiral allenamides2 4 had been used in highly stereoselective inverse-demand hetero (4 + 2) cycloaddition reactions with heterodienes.5 These reactions lead to stereoselective synthesis of highly functionalized pyranyl heterocycles. Further elaboration of these cycloadducts provides a unique entry to C-aryl-glycosides and pyranyl structures that are common in other natural products (Scheme 1). 

N-Aryl-N, N -dialkylurea herbicides 43 Aryl glycosides 185,186 Aryloxybutanolamine derivatives 45 N-Arylthiosemicarbazides 248 Ascorbic acid 216,256,257,372-374,376, 377, 426... 

This methodology has been applied to carbohydrate derivatives and provides a route to certain C-aryl glycosides. 

The glycosylation based on the Mitsunobu reaction has been most commonly directed to the synthesis of O-aryl glycosides, a structural motif found in a variety of natural products [80-82], Early work by Grynkiewicz [83,84], among others [85-87], established the viability of triphenylphosphine and diethylazodicarboxylate to promote the glycosylation of phenol acceptors at ambient temperature. More recently, Roush and coworkers have discovered that the glycosylation performed well in the... 

Scheme 6.12 Rearrangement to C-aryl glycosides from aryl O-glycosides following a-selective synthesis using glycosyl phosphates.

In section H notes are appended on the preparation of specific classes of glycosides — furemosides, a-glucosides, aryl glycosides and polysaccharides. 

Aryl glycosides of 2-amino-2-deoxy sugars, as might be expected, can be prepared by similar techniques as was illustrated by the synthesis of phenyl 3,4,6-tri-0-acetyl-2-acetamido-2-deoxy-p-D-glucoside and -D-galactoside by toluene -sulphonic acid catalysed reactions between phenol and the hexosamine penta-acetates These products were then anomerised using zinc chloride as catalyst to provide means of obtaining -anomers. 

With exception of the alcoholysis reaction the methods described earlier are all applicable to the synthesis of aryl glycosides, but, in particular, reactions of phenols with glycosyl esters in the presence of acidic catalysts are generally useful. 

C-Aryl-glycosides are wide-spread in Nature (34., 35). The biological importance led to various synthetic... 

K. C. Nicolaou, H. J. Mitchell, F. L. van Delft, F. Riibsam, and R. M. Rodriguez, Expeditious routes to evemitrose and vancosamine derivatives and synthesis of a model vancomycin aryl glycoside, Angew. Chem. Int. Ed., 37 (1998) 1871-1874. 

Spirocyclic C-aryl glycosides are central structural skeletons of papulacandins that constitute a family of novel antifungal antibiotics isolated from a strain of Papularia sphaerosperna. They have shown potent in vitro antifungal activity against Candida albicans, Candida tropicalis, Pneumocystis carinii, among other microorganisms [110],... 

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