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Lithiated alkoxyallenes are very versatile components for the synthesis of heterocycles such as furans, pyrroles, and 1,2-oxazines, easily allowing the preparation of natural products via these heterocyclic intermediates. A surprising three-component synthesis of N-acylated enaminones allowed the synthesis of highly functionalized 4-hydroxypyridines, 5-acetyloxazoles, and pyrimidines. All these heterocyclic products are ready for further functionalizations, in particular for palladium-catalyzed reactions, leading to libraries of new interesting heterocycles. [ABSTRACT FROM AUTHOR]

Protected dihydroxylated 1,2-oxazine derivatives such as RAC- 4 were converted into tetrahydro-1,2-oxazines RAC- 7 by employing BH 3?THF for the stereoselective reduction of the C=N bond. Compound 7A underwent a reductive ring contraction on hydrogenation in the presence of palladium on charcoal to provide RAC- 5 in good yield. Enantiopure 1,2-oxazine derivatives 13 and 14 were prepared using (-)-menthol as chiral auxiliary. Their diastereo?selective dihydroxylation and BH 3?THF reduction furnished enantiopure tetrahydro-2 H-1,2-oxazine derivatives 17 and 18 in good overall yield. Enantiomers (6 R)- 18 and (6 S)- 18 were transformed into the two enantiomeric hydroxylated pyrrolidine derivatives 5 in moderate yield. [ABSTRACT FROM AUTHOR]

Gold colloids with terminally functionalized sulfated thiol shells were found to bind to P- and L-selectins with IC50values in the picomolar range; branched acyclic epitopes show the highest affinity, whereas a sulfated carbohydrate mimetic provides the best selectivity. [ABSTRACT FROM AUTHOR]