Aldehyde group, carbohydrate component

In Section 17.9 we explored the use of diols to protect carbonyl groups. Entry 5 shows how carbohydrates can function as the diol component in forming a cyclic acetal from benzaldehyde, thereby protecting two of the carbohydrate s hydroxyl groups. This is yet another example of acetal formation, in this case involving the aldehyde group of benzaldehyde and the C-4 and C-6 hydroxyl groups of the carbohydrate. 

Carbohydrates are the most abundant organic component of plants. Structurally, carbohydrates are usually polyhydroxy aldehydes or polyhydroxy ketones (or compounds that hydrolyze to yield polyhydroxy aldehydes and ketones). Since carbohydrates contain carbonyl groups and hydroxyl groups, they exist primarily as acetals or hemiacetals. 

Oxa-Diels-Alder reactions between l-oxy-3-silyloxybuta-1,3-dienes and aromatic aldehydes (either component being attached to a carbohydrate auxiliary) have been investigated by Stoodley et al. [109,110], drawing on the pioneering work of the Danishefsky group [111,112]. For example, the reaction of the carbohydrate-linked diene 143 with p-nitrobenzaldehyde in the presence of Eu(III) catalysts gave dihydropyrans 144-147 [109] (Scheme 10.47). When the chiral Eu complexes (- -)-Eu(hfc)3 and (—)-Eu(hfc)3 were used, double stereodifferentiation was... 

The presented review describes total syntheses directed towards 6-amino-6,8-dideoxy-D-eryt/iro-D-galacto-octose, commonly named lincosamine - the sugar component of the antibiotic lincomycin. In the first part we present total syntheses of lincosamine that start from carbohydrate precursors. The D-galactose-derived aldehyde is the most frequently used synthon. In the second part, total syntheses of lincosamine from non-carbohydrate precursors are presented. This part of the review is divided into two subsections. The first one groups syntheses based on the application of furan compounds. In the second one we present a hetero-Diels-Alder approach to the synthesis of lincosamine. 

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