Development of reactions of 6-and 5-substituted 1,3-dimethyluracils with dimethylsulfoxonium methylide

6-Chloro-1,3-dimethyluracil (1) reacts with dimethylsulfoxonium methylide ( 3, 2 equiv) to give sulfoxonium ylide 8 (51%). The structure of 8 is establ ished spectroscopically and by its reactions with various electrophiles and electron-deficient olefins. Thus, 8 is converted by HCl to sulfoxonium chl oride ?, which then yields the 6-(chloromethyl)uracil 17 by heating in acet onitrile. Ylide 8 undergoes deuterium exchange at the Ei-position, at its m ethine carbon, and into its methyl groups attached to sulfur. Reaction of 8 with benzoyl chloride gives the highly substituted ylide 19 or the nucleop hilic substitution products 17 and 18 depending on reaction conditions. Tre atment of 8 with electron-deficient olefins yields 6-cyclopropyluracils 20- 31. Many of the cyclopropyluracils have been converted to trans-1-(1,3-dime thyluracilyl)-2-vinylcylopropanes and cycloheptenyluracils. Reactions of 5- substituted uracils 2 (Z = SOPh and SeOPh) with ylide 3 have been developed . 5-(Phenylsulfinyl)uracil 48 yields cyclothymine derivative 49; 5-phenylse leninyluracil 52 gives methylide 8 as the major product.