Synthesis of Glycosylated Natural Products and Their Analogues

Glycosidation of long chain alcohols of glycolipids with G-acetylated 2-acetamido-2-deoxy-a-D-glucopyranosyl chloride using various activators has been reported. 

0-Glycosylated a-amino acids continue to receive considerable attention and several methods may be applied to their synthesis. For example, compounds 44, based on threonine, are 

Interest continues in glycosylated derivatives of cyclitols and related compounds (see also Chapter 18). Thioglycoside technology was used to synthesize compound 45 vriiich is an analogue of the chromophore of neocarzinostatin. Various and cAiro- inositol 

In the field of glycosylated steroids the following have been synthesized the 6-deoxy-P-D- 

3 7-Glycosides Isolated from Natural Products.—As usual, only compounds showing special features, either structural or biological, are dealt widi in this section. 

2 Synthesis of Glycosylated Natural Products and Their Analogues - Very appreciable interest remains in glycosides having functionalized acyclic aglycons. Dimeric coupling of derivatives of compound 19 led to 20, the core portion of cycloviracin Bi, which is a recently discovered anti-herpes compound. 

Various cerebrosides to have been reported are the P-D-glucopyranosyl compound which is the major component of Penicillium cerebrosides, an a-galactosylated cerebroside, the ceramide asymmetric parts of which were made from lyxose, which is described in Chapter 24, and the P-galactosyl compound 22 which shows anti-viral activity.  

2-diol carrying an a-L-fucosyl unit and a 4-benzyloxy-3-(3-carboxyethyl)phenyl as hydroxyl substituents. Reaction of tri-O-acetyl-2-phthalimido-D-glucal with a monohydroxy deoxyinositol phosphate ester in the presence of boron trifluoride gave a 2,3-unsaturated inositol phosphate for use in the synthesis of anchor compound analogues.  

A variety of ring A fluorinated anthracyclines, for example 30, were synthesized either by glycosylation of fluorinated aglycons or by modification of the aglycons of daunorubicin or idarubicin, and their antitumor properties were evaluated. In related work, 4-demethoxy-6,7-dideoxydaunomycinone analogues, for example 31, have been synthesized. 

2 Synthesis of Glycosylated Natural Products and Their Analogues. - In the 

Considerable activity continues with 0-glycosyl amino-acids. Two reports have appeared on 3-D-galactopyranosyl L-hydroxylysine derivatives,the first in connection with the development of assays for osteoporosis. An extensive range of related compounds W (with R = alkyl and fluoroalkyl), as well as related thioglycoside and 2-N-acetyl-2-deoxy compounds have been made as GalCer analogues for anti-HIV testing.  

Compounds 65, with R = H or tetra-O-acetyl-a-D-glucopyranosyl, have been made as 0-P-D-glucosylserine analogues for studies of glycosylated a-aminooxy 

A new block synthesis of peptides can be applied with 0-glycosylated derivatives, and in this way the 82-mer diptericin 70 has been made by methods involving the coupling of cysteine to a benzylthio ester. Solid phase methods were used to make serglycin glycopeptides e.g. 71.  

The 3p-hydroxy triterpenes of the oleanane, ursane and lupane series have been converted to the 2-deoxy- and 2,6-dideoxy-a-L-arafcmo-hexopyranosyl derivatives by addition processes applied to L-glucal and L-rhamnal. p-Gluco-sides of diol 78 (R = R = H) have been made with the sugar bonded separately to each of the hydroxyl groups.  

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