Alkynic sugar, synthesis

Fig. 4 Synthesis of glycopolymers via CuAAC of alkyne sugar with azido fimctional insulin...

Owing to flexibility in the substrate, the TycATE was also used to synthesize a variety of novel cyclic structures. Inclusion of a propargylated amino acid into the linear substrate allowed the synthesis of over 247 macrocyclic glycopeptides, where azido-sugars were coupled onto the cyclized alkyne via copper-catalyzed 1,3-dipolar cycloaddition [44] (Figure 13.12). 

Acetylenic precursors employed in the syntheses of sugars may be divided into three groups (a) aldehydes (usually in the form of acetals), (b) alkyl alkynyl ethers, and (c) alkynols or alkynediols. Some of them are commercially available (for example, 2-butyne-l,4-diol), and others are prepared by Grignard-type reactions between 1-alkynylmag-nesium halides or lithium alkynes and suitable aldehydes, ketones, or epoxides. In this way, the synthesis of substrates having the desired number of carbon atoms, as well as the necessary functional groups, can be achieved. The next step consists in partial saturation of the triple bond to afford the desired cis- or trans-alkene. ct.s-Alkene systems... 

The first contribution in the development of sugar arrays based on cHck chemistry was reported by Fazio et al. [79] who described the use of Cu(l)-catalyzed triazole formation for the synthesis and in-situ non-covalent attachment of saccharides to the surface of microtiter plates through Hpid tethers (Scheme 23). The alkyne cHckable counterpart was prepared from a Ci4 aliphatic chain that was conjugated with a series of 2-azidoethyl -D-glycosides on miaomolar scale by using an experimental protocol that avoided purification procedures, hi an effort to extend this approach to the covalent attachment of saccharides to the microtiter plate surface, Bryan et al. [80] reported a strategy based on bifunctional Hnkers (115 and 116). 

Figure 2.11 Synthesis of an alkyne side functional polymer and introduction of azido sugar ligands via CuAAc. ...

Fig. 3 Synthesis of glycopolymers via CuAAC of azide sugar with alkyne functional polymer or monomer...

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