The sodium salt of 1,3,6-trimethyl-5-nitrouracil is shown to react wit
h various reductive alkylating agents such as p-nitrobenzyl chloride a
nd dinitropropane by an S(RN)1 mechanism to give new potentially bioac
tive 5-nitrouracil derivatives. 1,3-Dimethyl-5-nitro-6-chloromethylura
cil also reacts by an S(RN)1 mechanism with 2-nitropropane anion to af
ford a new uracil derivative being a trisubstituted ethylenic double b
ond at the 6-position.