for the following products
(Z)-1,5-Dimethylbicyclo[ 3.3.0 ] octane-3,7-dione | 1-(3,5-di-O-P-Chlorobenzoyl-2-deoxy-β-D-ribofuranosyl)-5-ethyluracil | [(2R,3S,5R)-3-(4-chlorobenzoyl)oxy-5-(5-ethyl-2,4-dioxopyrimidin-1-yl)oxolan-2-yl]methyl 4-chlorobenzoate and 5-Ethyl-3',5'-bis-(4-chlorobenzoyl)-2'-beta-deoxyuridine
