Regiochemistry of epoxide ring opening in methyl 2,3-anhydro-4-azido-4-deoxy-α- and β-l-lyxopyranosides

Design, synthesis and in vitro antitumour activity of new goniofufurone and 7- epi -goniofufurone mimics with halogen or azido groups at the C-7 position

“…The reaction of 13 with carbon tetrabromide and triphenyl phosphine gave 7-bromo derivative 15 in 28% yield. Absolute value of optical rotation of our sample 15 20 D +10.9 (c 1.8, CHCl 3 )} is somewhat smaller, but of an opposite sign, than the reported value for the enantiomer ent-15 {[α] 20 D −22.0 (c 1.8, CHCl 3 )} [24]. However, the melting point {lit.…”

“…Apart from being an isostere, the azido group has been extensively used in joining two entirely different building blocks ("click reaction"), thus enabling an easy access to highly complex molecular architectures of interest for both medicinal chemistry and chemical biology [17,18]. In order to prepare azido isosteres 11 and 12 we have adopted a literature procedure that was previously applied for the epoxide ring opening by using trimethylsilyl azide/boron trifluoride diethyl etherate reagent system [19,20]. The synthesis of azido derivatives 11 and 12 started from the known oxetane 28 (Scheme 4) that is readily available from 7-epi-(+)-goniofufurone in one step [15].…”

An efficient synthesis of selectively functionalized d-rhamnose derivatives

“…21 Several other examples of the nucleophilic opening of anhydro sugars have been reported, and in many of these papers both the regio-and stereochemical outcome of the opening can be controlled by varying either the type of nucleophile being used or by alteration of hydroxy protecting groups. 19,20,[24][25][26] For our 3,4-anhydro derivative 10, nucleophilic attack at C-3 would result in a ido-configured sugar, whilst nucleophilic attack at C-4 would return a manno-configured sugar. Unfortunately however, in our hands the anhydro sugar 10, or the 2-acetyl analogue 12, were surprisingly robust compounds.…”