One-carbon extrusion from carbohydrates via C1-alkoxy radical fragmentation. An easy access to erythrose and threose

Generation and fragmentation of the C1-alkoxy radicals of pyranose derivatives are nicely promoted by (diacetoxyiodo)benzene or lead tetraacetate in the presence of iodine catalyst under mild conditions to give the corresponding mixed-acetal formates which are further converted to the furanose derivatives by acid-catalysed transacetalization.