Reversible generation of glycosyl radicals from telluroglycosides under photochemical and thermal conditions

Intermolecular Addition of Glycosyl Halides to Alkenes Mediated by Visible Light

“…Perhaps the most identifiable methodology for their synthesis is the Bu 3 SnH‐mediated radical addition of glycosyl bromides to activated alkenes 4. Since its discovery, several variations of this reaction have been reported, including the utilization of transition metals5 or UV light6 to initiate the reaction. Our group recently developed a nickel‐catalyzed reductive coupling of glycosyl bromides and alkenes, mechanistic studies on which suggested that the nickel catalyst was playing an electron‐transfer (ET) role,7 which implied that other compounds that are known to facilitate ET processes might behave even better (for example, [Ru(bpy) 3 ] 2+ ; bpy=2,2′‐bipyridyl).…”

New Insights into the Stoichiometric and Catalytic Reactivity of Unsaturated Pd3(dppm)3COn+ Clusters (n = 0, 1) Towards Halocarbons – First Evidence for Inorganic By‐Products

“…The electrolysis proceeds as shown in Scheme The addition of the spin trap DMPO to the solution during catalysis (entry 4) leads to the formation of the spin adduct as shown in reaction (1). On the other hand, addition of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) [45][46][47][48] (entry 5) leads to a partial trapping where Bz 2 and the diamagnetic spin adduct can be observed [reaction (12)]. …”

Dissecting the Influence of Oxazolidinones and Cyclic Carbonates in Sialic Acid Chemistry

“…[8] Anomeric radical reactions are well known to give rise to axially quenched products under kinetic conditions, [9] with the notable exception of the sialic acids wherein poor selectivity is found. [10] Conversely, the equilibration of anomeric stereochemistry via radical intermediates is rare [11] and has not been applied explicitly to the study of the anomeric effect.Attempted synthesis of sialosyl glycosides of 2,2,6,6tetramethylpiperidine-1-ol (TEMPOL) were fruitless, so we focused on radical approaches to the desired glycosides. The known S-sialosyl xanthate 1 [12] was photolyzed in dichloroethane at room temperature in the presence of 2,2,6,6tetramethylpiperidine N-oxide (TEMPO; 20 equiv), thus leading to a 69 % yield of the desired TEMPO glycoside 2 as a separable 1:2 mixture of a-and b-anomers (Scheme 1).…”