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Scheme 40
Scheme 41
Scheme 42

bromide followed by acylation) to Pd(dppe)2 and sodio malonate gave the chain-extended C-glycoside derivative 236 in 71% yield. Several other examples were studied and gave comparable yields of C-glycoside products [66].

C. Use of Cobalt

Luengo and Gleason utilized Murai's cobalt chemistry to produce the equatorial C-glycoside 238 in 85% yield, followed by desilylation and conversion of 239 to 241. The final step, standard coupling, then gave 244 the potential GDP-fucose inhibitor (Scheme 45). Several other analogs were also prepared [67].

Scheme 43

Scheme 44

Co2(C0)8,C0

,OSiEt,Me HOAc

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