Glycals iodo substituted

Where Ci stannylated glycals have been useful in the formation of C-glycosides, zinc and iodo substituted glycals have provided complimentary avenues to these compounds. Utilizing either of these classes of glycals, the results of the coupling reactions were shown to be highly susceptible to the transition metal catalyst used. 

C.ii.e. Heck Reaction The cross-coupling between 5-iodoimidazoles and methyl acrylate has been appUed to complex structures as depicted for the preparation of (E S-(2-carbomethoxyvinyl)-l-(2,3,5-lri-0-acetyl-i eM-Z)-ribofuranosyl)imidazole-4-carboxamide 142 from the corresponding 5-iodoimidazole (Scheme 59). Acrylonitrile reacts in the same manner under Heck conditions to provide the ( )-5-cyanovinyl derivative. The C-glycosyl bond formation in the Heck coupling between the 3-iodopyrazolo[4,3-dlpyrimidine 143 and the ribofuranoid glycal 144 was regio- and stereospecific. The iodo substituent in the substrate was introduced by a simple electrophilic substitution. ... 

---