1-[(1R,2R,4R,5R)-4-(hydroxymethyl)-7-oxido-7-oxo-3,6,8-trioxa-7$l^{5}-phosphabicyclo[3.3.0]octan-2-yl]pyrimidine-2,4-dione 1-[(1R,2R,4R,5R)-7-keto-4-methylol-7-oxido-3,6,8-trioxa-7$l^{5}-phosphabicyclo[3.3.0]octan-2-yl]pyrimidine-2,4-quinone