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Scheme 3 Synthesis of 1 via a Weinreb amide here shown with the modifications of the Taylor group. 17Scheme 4 1 and 8 as precursors for the and -2-aminohydroxypropyl structural element.

The established rates of glycoside hydrolysis reactions were analyzed using free energy relationship plots based on substituent constants that depend on whether the substituent is axial or equatorial. In all cases good correlations were found when assuming either that the transition state had a charged ring-oxygen atom or that it had a charged anomeric carbon atom. The spontaneous hydrolysis of 2,4-dinitrophenyl beta-glycopyranosides and the acidic hydrolysis of methyl beta-D-glycopyranosides were found to give a good correlation, when 100% charge at the ring-oxygen in the transition state of these reactions is assumed. The acidic hydrolysis of methyl alpha-glycopyranosides was found to give good correlations regardless of whether 100% charge at the ring-oxygen or 100% charge at the anomeric carbon was assumed. The findings clearly demonstrate how crucial the stereochemistry of even remote polar substituents is for their electronic effect on chemical reaction.

For the first time the two enantiomeric forms of the glycosidase inhibitor 1-azafagomine have been synthesised starting from D- and L-xylose. D-Xylose was converted to the 2,3,5-tribenzylfuranose, which upon reductive amination with tert-butyl carbazate gave the protected 1-hydrazino-1-deoxypentitol in high yield. N-acetylation, mesylation of the 4-OH, removal of the Boc group, cyclisation and deprotection gave (+)-1-azafagomine ((+)-1). By a similar sequence of reactions, L-xylose was converted to (-)-1-azafagomine ((-)-1). Enzymatic and other routes to optically pure 1-azafagomine were also studied. Compound (-)-1 is a potent competitive glycosidase inhibitor, while (+)-1 has no biological activity. The inhibition of almond beta-glucosidase by (-)-1 was found to be slow owing to a slow binding step of inhibitor to enzyme, with no subsequent conformational rearrangement. The rate constants for binding and release were found to be 3.3 x 10(4)M(-1)s(-1) and 0.011 s(-1), respectively, yielding Ki = 0.33 microM.

A high-yielding method was developed for the preparation of ingenol 3-angelate (PEP005, ingenol mebutate) via the corresponding 5,20-acetonide without concomitant isomerization of the angelate (Z-form) to the corresponding tiglate (E-form). The general scope of the stereoconservative esterification method was further evaluated on several different alcohols, giving the angelates in up to quantitative yield without isomerization to the tiglate.

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Azides Q 0170 Rapid Synthesis of Aryl Azides from Aryl Halides under Mild Conditions. -In the presence of catalytic amounts of CuI, diamine CDA, and sodium ascorbate, aryl azides are rapidly prepared from aryl bromides or iodides. In the latter case, the reaction proceeds even at room temperature. -(ANDERSEN, J.; MADSEN, U.; BJOERKLING, F.; LIANG*, X.; Synlett 2005, 14, 2209-2213; Dep. Med. Chem., Leo Pharm. Prod., DK-2750 Ballerup, Den.; Eng.) -Klein 02-076