Stereocontrolled cyclization at the anomeric position of 6-(hydroxyalkyl)uridines using hypoiodite reaction

Hypoiodite reaction of 6-(hydroxyalkyl)-2',3'-O-isopropylideneuridines (1-3) was found to yield a new class of spiro nucleosides having an anomeric orthoester structure. It appeared that the 6-hydroxyalkyl substituent and the 2',3'-O-isopropylidene group are working cooperatively to control the anomeric stereochemistry (beta/alpha = 35/1-2/1) of the cyclization.