The sodium salt of 1, 3, 6-trimethyl-5-nitrouracil is shown to react with various reductive alkylating agents such as p-nitrobenzyl chloride and dinitropropane by an SRN1 mechanism to give new potentially bioactive 5-nitrouracil derivatives. 1, 3-Dimethyl-5-nitro-6- chloromethyluracil also reacts by an SRN1 mechanism with 2-nitropropane anion to afford a new uracil derivative bearing a trisubstituted ethylenic double bond at the 6-position.