A simple desymmetrisation approach to unsymmetric N,N'-disubstituted cyclic ureas
Bew SP., Bull SD., Davies SG., Eames J., Baxter AD., Mykytiuk J.
The bis-enolate derived from 1,3-di-isobutyryl-trans-4,5-tetramethylene- imidazolidin-2-one 8 is unstable and deacylates to afford dianion 11 which can be regioselectively alkylated to afford unsymmetric cyclic urea 17 in good yield. Subsequent deacylation of 17 and methylation on nitrogen affords unsymmetric 1-benzyl-3-methyltrans-4,5-tetramethyleneimidazolidin-2-one 19 in good yield.