Synthesis and Properties of N,N′-Disubstituted Ureas and Their Isosteric Analogs Containing Polycyclic Fragments. XX. N-[(3,5-Difluoroadamantan-1-yl)]-N′-R-ureas and Symmetrical Bis-ureas

A procedure has been developed for the synthesis of 3,5-difluoroadamantan-1-yl isocyanate from 3,5-difluoroadamantane-1 carboxylic acid and diphenylphosphoryl azide using a new fluorinating agent, Ishikawa reagent, in one stage of the synthesis. The reaction of 3,5-difluoroadamantan-1-yl isocyanate with aliphatic diamines and trans-4-[(4-aminocyclohexyl)oxy]benzoic acid afforded a series of N,N′-disubstituted ureas and bis-ureas in 43–96