Synthesis of a beta-(1-->3)-D-rhamnotetraose by a one-pot, multiple radical fragmentation

A naturally occurring beta-(1-->3)-D-rhamnotetraose has been constructed under conditions of sequential beta-selective mannosylation controlled by the 4,6-O-1-cyano-2-(2-iodophenyl)-ethylidene] protecting group. The route is concise, proceeding through a late-stage radical deoxygenation that successfully uncovers all four deoxy subunits at once.