Glycosyl trichloroacetamide

PALLADIUM- AND NICKEL-CATALYZED STEREOSELECTIVE SYNTHESIS OF GLYCOSYL TRICHLOROACETAMIDES AND THEIR CONVERSION TO a- AND P-UREA GLYCOSIDES... 

FIGURE 15.5 Neutral Pd(n)-catalyzed stereoselective formation of 3-N-glycosyl trichloroacetamide. 

FIGURE 15.6 Optimization for stereoselective synthesis of p-iV-glycosyl trichloroacetamide with o-donor ligands. 

Figure 2.15 Automated solid phase oligo-/polysaccharide synthesis. Glycosyl donor (A) is coupled to a solid phase Merrifield-like resin through an alkenyl alcohol linker. The double bond allows for clean removal of product at the end of solid phase synthesis by metathesis using Grubb s catalyst in the presence of ethylene gas. For protecting groups, see Fig 2.13. Trimethyl silyltriflate (TMSOTf) activates the glycosyl donor through controlled removal of the trichloroacetamidate.

To study this possibility, glycosylation with iron(iii) triflate was examined by varying the electronic and/or the steric properties of the N-substituent in o-glucosaminyl donors 83-85. This was done taking the glycosylation of primary alcohol 77 under the optimized conditions (entry 3, Table 4) as a reference test. Similarly to 1, tolylamide 83 provided the expected glycoside 86, while trichloroacetamide 84 or pivaloyl amide 85... 

DEVELOPMENT OF THE STEREOSELECTIVE NICKEL-CATALYZED TRANSFORMATION OF GLYCOSYL TRICHLOROACETEMIDATES TO TRICHLOROACETAMIDES... 

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