Switching Between Reaction Pathways By An Alcohol Cosolvent Effect: Smi2-Ethylene Glycol Vs Smi2-H2o Mediated Synthesis Of Uracils

A chemoselective switch between reaction pathways by an alcohol cosolvent effect in a general SmI2-mediated synthesis of uracil derivatives is described. The method relies on the use of coordinating solvents to increase the redox potential of Sm(II) and results in a chemoselective 1,2-reduction (SmI2H2O) or 1,2-migration via in situ generated N-acyliminium ions (SmI(2)ethylene glycol, EG). This work exploits the mild conditions of the SmI2-mediated monoreduction of barbituric acids and offers an attractive protocol for the synthesis of uracil derivatives with biological activity from readily accessible building blocks.