Diastereoselective access to ,-glycosyl amino acids iron-catalyzed, auxiliary-enabled MHAT coupling.

Access to ,-glycosyl amino acids as a novel class of glycomimetics is reported by means of radical generation, intermolecular addition and stereoselective reduction a metal-induced hydrogen atom transfer (MHAT) sequence. The 'matched' coupling of -D-glycals with an enantiopure dehydroalanine bearing a ()-configured benzyl oxazolidinone enables a singular case of two-fold diastereocontrol under iron catalysis. In the common -D-glucal series, the nature of the C-2 substituent was found to play a key role from both reactivity and stereocontrol aspects.

Formal Glycosylation of Quinones with -Glycals Enabled by Iron-Mediated Oxidative Radical-Polar Crossover.

The intermolecular C-O coupling reaction of 1,4-quinones with -glycals under iron hydride hydrogen atom transfer (HAT) conditions is described. This method provides a direct and regioselective access to a wide range of phenolic -ketosides related to biologically relevant natural products in diastereomeric ratios up to >98:2 in the furanose and pyranose series. No trace of the corresponding -glycosylated products that might have resulted from the radical alkylation of 1,4-quinones was observed.

Stereoselective Synthesis of ,-Glycosides from -Glycals Enabled by Iron-Mediated Hydrogen Atom Transfer.

We describe herein a convenient strategy for the construction of ,-glycoside building blocks via the intermediacy of tertiary pseudoanomeric radicals. Application of an iron-mediated hydrogen atom transfer/Michael-Giese coupling enables the anomeric quaternization of readily available -glycals with good to complete stereocontrol in the pyranose and furanose series. Carefully optimized conditions allow the use of challenging trisubstituted derivatives prone to undergo further elaboration to stable neoglycoconjugates.

Stereocontrolled synthesis of polyhydroxylated bicyclic azetidines as a new class of iminosugars.

We report herein the development of a stereodivergent route towards polyhydroxylated bicyclic azetidine scaffolds, namely 6-azabicyclo[3.2.0]heptane derivatives.