De novo synthesis of differentially protected L-iduronic acid glycosylating agents.

A divergent de novo synthesis of six differentially protected l-iduronic acid thioglycosides from a common advanced precursor is described. The key step of this synthetic sequence is the stereoselective elongation of dithioacetal protected C5-dialdehyde 11 via a highly diastereoselective MgBr(2).OEt(2)-mediated cyanation. Orthogonally protected l-iduronic acid building blocks obtained by this synthesis are expected to facilitate access to differentially sulfated heparins for microarray-based structure-activity relationship studies.