Regio-and Stereoselectivity in Glycosylation

5 Armed-Disarmed Concept in the Synthesis of Glycosidic Bond 

The glycosylation of the OH-6 group of the myo-inositol derivative 141 with 2-azido-2-deoxy-D-glucopyranosyl trichloroacetimidates is another case of regioselective glycosylation of a 1,2-trans-O-diequatorial diol system 141 which is frequently performed for the preparation of building blocks for IPG synthesis [53]. 

Martin-Lomas et al. have already shown that the coupling of L-c/n o-inositol tetrabenzoate 142L with 2-azido-2-deoxy-3,4,6-tri-0-benzyl-D-glucopyranosyl trichloroacetimidate 143 gave a 6.4 1 mixture of the a(l — 3) 144 and a(l 2) 145 pseudodisaccharides in 61 % combined yield (Fig. 5.36). Similarly, 

In order to confirm the influence of the absolute configuration of the acceptor on the regioselectivity of these glycosylations, we may observe the results of the reactions of 142D with 152 (see Fig. 5.37), 142D with 154 (see Table 5.3) (for structures see Fig. 5.38), and MOL with 155 (not shown). 

At this point, the glycosylation of M2D and M2L with trichloroacetimidate 157, bearing a trifluoroacetamide participating group at C2, was investigated. 

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