Diastereoselective metal-catalyzed synthesis of C-aryl and C-vinyl glycosides.

ABSTRACT

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/ß ratios of 1.31-31.