Author/Authors :
Bridgeman، نويسنده , , Eve and Cavill، نويسنده , , Julie L. and Schofield، نويسنده , , Daniel J. and Wilkins، نويسنده , , Derek S. and Tomkinson، نويسنده , , Nicholas C.O.، نويسنده ,
Abstract :
A series of non-symmetrical tri- and tetra-substituted ureas have been prepared to mimic the rigid tetracyclic core of estradiol. Tetra-substituted ureas were prepared by a five-step protocol, involving activation and displacement of a carbonyldiimidazole adduct in 48–67% overall yield. This method was unsuccessful for tri-substituted ureas, which were prepared in 42–74% yields by an alternative four-step method, which included a one-pot 4-nitrophenyl carbamate formation/displacement sequence.
