Glucose acetobromo

Recently, a total synthesis of salmochelin SX (70) has been reported which used cross-coupling of acetobromo-a-D-glucose 96 with arylzinc derivative 97 to furnish 98, followed by full deacylation and perbenzylation to give 99. Subsequent saponification of the methyl/benzyl ester, formation of the acid chloride, and addition of a protected L-serine unit yielded 100. Final deprotection formed the glucosyl-DHB-serine 70 in 28% overall yield (Fig. 17) [121]. This strategy involved the stepwise addition of the aryl moiety and serine (76a) to the sugar portion, which is in the opposite order to the biosynthetic rationale. 

Isbell and Frush10 have reported an extensive study of the reaction of a-acetobromo-D-glucose with methanol, silver carbonate, and the water liberated in the reaction as by-product,... 

In contrast to the result obtained with a-acetobromo-D-glucose, Isbell and Frush10 found the reaction of a-aeetobromo-D-mannose under parallel... 

Hurd and Holysz34 obtained a 20% yield of tetra-O-acetyl-jS-D-gluco-pyranosylbenzene (CVIII) on reacting a-acetobromo-D-glucose (CVII) with one mole of diphenylcadmium in boiling toluene and, under the same conditions, a 29% yield of tetra-O-acetyl-a-D-mannopyranosylbenzene (CX) was obtained from a-acetobromo-D-mannose (CIX). The authors... 

In 1914, Fischer had treated acetobromo-D-glucose with silver thiocyanate and had obtained, as the acetyl derivative, the iso thiocyanate. This work was later extended by Fischer and by others and, fairly recently, by Muller and Wilhelms and by Wilhelms. These authors substituted potassium thiocyanate for the silver salt and, under the conditions employed, the product was the thiocyanate. However, when this was heated, it isomerized and the isothiocyanate, identical with that obtained by Fischer, resulted. 

Treatment of F with acetobromo-D-glucose under the conventional Konigs-Knorr conditions gave H, whose deacetylation afforded blattellastanoside A (171) as leaflets, mp 164-166 °C. The identity of our synthetic 171 with blattellastanoside A was confirmed by a comparison of their 1H- and 13C-NMR data and HPLC analysis. 

Blattellastanoside B (172) was also synthesized as shown in Figure 7.14.15 Reduction of the chloro epoxide A with diisobutylaluminum hydride was followed by acetylation to give B selectively, although the yield was only 29% with 68% of the recovered A. Treatment of B with sodium methoxide in methanol at 0°C yielded C, which afforded epoxy alcohol D by further treatment with sodium methoxide at 60 °C. Glucosylation of C with acetobromo-D-glucose was followed by deacetylation to give blattellastanoside B (172) as microcrystalline powder, mp 158-160°C. A comparison of the H- and 13C-NMR spectra of the synthetic 172 with those of blattellastanoside B proved the identity. 

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