Towards a General Access to 1-Azaspirocyclic Systems via Photoinduced, Reductive Decarboxylative Radical Cyclizations.

A convenient and versatile approach to important 1-azaspirocyclic systems relevant to medicinal chemistry and natural products is reported herein. The main strategy relies on a reductive decarboxylative cyclization of redox-active esters which can be rapidly assembled from abundant cyclic azaacids and tailored acceptor sidechains, with a focus on alkyne acceptors enabling the generation of useful exo-alkene moieties. Diastereoconvergent variants were studied and could be achieved either through remote stereocontrol or conformational restriction in bicyclic carbamate substrates.

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.