Analogs disaccharide

In the crucial step of the synthesis (Scheme 16), the disaccharide glycosyl donor 17 was used once again, in condensation with the acceptor 19 having two free OH groups, to produce the octasaccharide 20. This product was then converted in 7 steps via the 1-trichloroacetamido compound, analogous to the synthesis described in Scheme 15, into the final compound 21. 

C-Disaccharide analogs of trehalose were recently [20c] prepared by using as a key step an aqueous Diels-Alder reaction between the sodium salt of glyoxylic acid and the water soluble homochiral glucopyranosil-l,3-pentadiene 19 (Equation 6.1). A mixture of four diastereoisomers in a 41 24 21 14 proportion was obtained after esterification with methanol and acetylation. The main diaster-eoisomer 20 was isolated and characterized as benzoyl-derivative. 

As shown in Eq. 12.54, with glyoxylate as the dienophile, if the attack is on the si face of the diene, it would lead to the skeleton of KDO if the attack is on the re face, it would lead to the skeleton of KDN. C-Disaccharide analogs of trehalose were prepared using an... 

The importance of substituent and conformational effects in glycal additions was also demonstrated in attempting Michael addition of an alkoxide to the O-linked 2-nitrogalactal 1S3 and its C-linked analog 154. The a-toio-isomer 156 was obtained from 154 in contrast to the result of Michael addition to the analogous O-linked disaccharide 153, which eventually gave the 2-acetamido-a-galactoside-terminated disaccharide 155. 

P. Vogel, S. Gerber-Lemaire and L. Juillerat-Jeanneret, Imino -C- disaccharides and analogs synthesis and biological activity, in Imino sugars, from synthesis to therapeutic applications, ed. P. Compain and O. Martin, Wiley, 2007, pp. 87-130. 

In entirely analogous fashion, the selective esterification of various other common disaccharides by other acylating agents was investigated. One notable example is the selective benzoylation of methyl (3-lactoside with benzoyl chloride, which again produced many interesting results that are recorded in a series of papers with Ram... 

Further functionalization at OH-2 was also explored [187]. From monosacchari-dic (ot-gluco, 129) and disaccharidic (a-malto, 143) CMGLs, several types of bisfunctionalized systems were synthesized by reaction with allylamine or propar-gylamine. For example, compound 155 was prepared and used in a synthesis of the nucleotide sugar analog 156 (Scheme 38). In the context of studies on the... 

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