Glycosylmanganese Pentacarbonyl Complexes

Oxidative Addition of Glycosylbromides to trans-Ir(PMe3)2(CO)Cl

“…The 31 P{ 1 H} NMR shows a characteristic AB quartet at −36.5 and −36.8 ppm ( 2 J P−P = 105 Hz). Although no other solid-state structures of glycosyl metal complexes have been reported, the preferential equatorial orientation of the metal is supported by previous NMR analyses. − …”

“…Although anomeric effects present a means to potentially control the stereochemistry of metal-catalyzed reactions occurring at the C1 carbon of sugars, few studies have addressed the question of how anomeric effects influence oxidative addition reactions at C1. In the case of glycosyl halide electrophiles it has, however, been demonstrated that clean invertive oxidative addition by anionic nucleophiles is possible when the reactions are fast (e.g., [Mn(CO) 5 − ] − or [CpFe(CO) 2 − ]). Sluggish reactions, however, are poorly selective, since halide byproducts initiate Lemieux anomerization processes that erode the stereospecificity .…”

Carbohydrates tagged with the CCo3(CO)9 cluster †

“…15 Carbene complexes of deprotected and protected sugars are known. 16 Protected glycopyranosyl bromides react stereoselectively with organometallic compounds of cobalt, 17 iron, 18 and manganese 19,20 to give glycosyl complexes. Pyranosyl and furanosyl organometallic complexes undergo insertion reactions resulting in the formation of C-glycosyl derivatives with the reaction rates dependent on the configuration of the anomeric center bound to the metal.…”