for the stereoselective construction of all-carbon quaternary centers on acyclic molecules using a two-step tandem process is reported. The first step involves an intramolecular and stereoselective atom transfer radical cyclization reaction from an allyl or vinyl subunit attached on a silyloxy, serving as a tether, to a tertiary radical α to an ester. A subsequent mild acidic elimination leads stereoselectively
of novel xylo-like nucleosideanalogues bearing a C3’ all-carbon quaternary center and a C2’hydroxy substituent is described. Synthesis of this scaffold makes use of highly diastereoselective transformations on acyclic substrates. Central to the approach is formation of a 2,4-syn cyanohydrin from cyanide addition onto an aldehyde through a proposed seven-membered ring chelate using a bidentate Lewis