The triphenylstannyl p-u-glucopyranoside 4 was synthesized in one step from the 1.2-anhydro-a-uglucopyranose 3 with (hiphenylstannyl)lithium (Scheme 1). Transmetallation of 4 with excess BuLi, followed by quenching the dianion 7 with CD,OD gave (1s)yield (Scheme 2). Trapping of 7 with benzaldehyde, isobutyraldehyde, or acroleine gave the expected p-Dconfigurated products 11,12, and 13 in good yields. Preparation of C-acyl glycosides from acid chlorides, such as acetyl or benzoyl chloride was not practicable, but addition of benzonitrile to 7 yielded 84% of the benzoylated product 14. Treatment of 7 with Me1 led to 15 (30%) along with 40% of 18, C-alkylation being accompanied by halogen-metal exchange. Prior addition of lithium 2-thienylcyanocuprate increased the yield of 15 to 50% and using dimethyl sulfate instead of Me1 led to 77% of 15. No a-u-anomers could be detected, except with ally1 bromide as the electrophile, which yielded in a 1:l mixture of the anomers 16 and 17.

oxidation of the R u 2 + center is much more positive than that of the other complexes, but the peak reduction potentials remain remarkably constant. However, what is clear is that the electrochemical processes are chemically irreversible, showing almost no perceptible return upon scan reversals. There is only a hint of a return cathodic wave for Ru3+/Ru2+ at + 0.532 V, but none could be detected upon anodic reversal after reduction of the terpyridines.The reason for the observed chemically irreversible voltammetric responses is currently not well understood. It is possible to speculate that, due to the increased steric hindrance for 9< Ru > 12, either reduction or oxidation leads to sufficient destabilization. These redox processes occur in the vicinity of the metal center and could result in decomposition of the complex. Such a redox-driven "unlocking" of a complex could form the basis for a reversible formation-decomposition mechanism.This possibility, as well as the full characterization of the redox products, are currently under intense investigation.In summary, this construction concept allows the synthesis of specific polymacrocascade networks. as well as the incorporation of metal receptor units on or at a precise depth inside the macromolecule, to be controlled. We confirmed earlier that it is possible to encapsulate relevant molecules[211 randomly within a lipophilic region or to bind them covalently at a specific locus in the interior of cascades.'222' We now demonstrate the application of directed complex formation to generate the first stages in the construction of dendritic networks through metal-centered connectivity.

Eine neuartige Verknüpfung zwischen dem anomeren Zentrum einer Pyranose und einer Aminosäure stellt die rechts gezeigte C‐glycosidische Amidbindung dar. Sie ließ sich durch Kupplung von Heptonsäuren mit einem β‐Aminoalaninderivat bilden. Sowohl das α‐ als auch das β‐Anomer konnten selektiv synthetisiert werden.

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Stereoselective Syntheses of Retro-Isomers of N-Glucoasparagine. -The novel, unnatural, glycosylated amino acid derivatives (VI) and ( VII) containing a new type of linkage between the anomeric center of pyranose and amino acid are obtained in good yields. -(FREY, O.; HOFFMANN, M.; KESSLER, H.; Angew. Chem. 107 (1995) 18, 2194-2195; Inst. Org. Chem.