Two new examples of the rare C→O migration of ethoxycarbonyl groups

Two new examples of a carbon→oxygen ethoxycarbonyl group shift are described. Treatment of 3-ethoxycarbonylnitromethyl-1,2-O-isopropylidene-6-O-p-toluenesulfonyl-α-d-allofuranose () with Bu4NF leads to a rearrangement to 5-O-ethoxycarbonyl-1,2-O-isopropylidene-3-nitromethyl-6-O-p-toluenesulfonyl-α-d-allofuranose (). Similar treatment of ethyl-3-O-benzyl-6-deoxy-6-nitro-d,l-glycero-d-glucoheptofuronate () gives 3-O-benzyl-4-O-ethoxycarbonyl-6-deoxy-6-nitro-d-glucopyranose ().