Octose derivatives

Catalytic osmylation of the allylic ethers and alcohols (12) led to the octose derivative (13) as the predominant isomer the Z) alkene (14.) gave the 7-epimer (15), in agreement with the empirical rule of Kishi that there will be an erythro-relationship between the oxygens at C-5 and C-6. The reaction sequence was also extended... 

Acyclic Alditols. - Brimacombe s group have published full details of their work on the stereoselective synthesis of higher sugars, some of which is covered in Chapter 2 other papers describe the Sharpless oxidation of the octose derivative (1) to give the oxiran (2), and hence the D-erythro isomer (3), osmylation... 

The C-vinyl unit (37) has been investigated as a component of the antibiotic aurodox and related compounds/ and the 2,6-anhydro-octose derivative (38), which is derived from the tetrahydropyranyl component of the antifungal agent ambruticin, has been made from L-arabinose by methods involving the use of methyl 3-nitropropanoate (Scheme 13), and thus its absolute stereochemistry is defined. 

Heptose and octose derivatives have been synthesized by way of nucleophilic C-alkylation of 1,2 3,4-di-0-isopropylidene-a-D-gfo/acro-1,5-hexodialdopyranose with the carbanions derived from 1,3-dithian and 2-methyl-1,3-dithian (Scheme 74) 330 -pjjg diastereoisomeric products could be formed in different proportions, depending on the solvent used. 

Several alkynes related to compound (29) were prepared by treatment of the corresponding dialdose derivative with alkynyl Grignard reagents, and by reduction and oxidation processes they were converted into a series of octose derivatives, e.g. reduction gave 7,8-dideoxy compounds and oxidation alkynyl glycos-6-uloses. ... 

Further examples of four-carbon chain-extensions with 2-(trimethylsilyloxy)furan (see Vol.24, Chapter 2, Scheme 7) have been reported. Application of this method to 0-isopropylidene-D-glyceraldehyde afforded D-glycero-D-talo-hepxosc triacetonide (41), and an iterative procedure gave D-g/ycero-D-ra/o-L-to/o-undecanose pentaacetonide. Similarly, a 8-0-benzyl-L-r/irca-D-ra/o-octose derivative was obtained from 4-0-benzyl-2,3-0-isopropylidene-L-threose. ... 

Burgess et al. developed a novel approach for the synthesis of polyhydroxylated compounds such as castanospermine 87 and swainsonine 89 ° utilizing alkoxyallylboration of as one of the key steps (Eigure 25.12). Similarly, Jadhav and Woerner were able to convert the octose derivative 90 into the polyhydroxyindolizidine 91 in seven further transformations (Figure 25.12). Several of these indolizidines exhibit potent anti-cancer, anti-viral, and anti-AIDS activities. 

---