Cobalt, the catalyst of choice: The diastereoselective cobalt‐catalyzed cross‐coupling of 1‐bromo glycosides and aryl or vinyl Grignard reagents is described. A convenient and inexpensive catalyst, [Co(acac)3]/tmeda (acac=acetylacetonate, tmeda=N,N′‐tetramethylethylenediamine), gives full α selectivity in the mannose and galactose series, and an α selectivity in the glucose series with α/β ratios of