1. Sandler, S. R. and Karo, W. 1971.Organic Functional Group Preparations, Vol. II, 135–165. New York: Academic Press.
2. A New Convenient Method for the Synthesis of Symmetrical and UnsymmetricalN,N′-Disubstituted Ureas
3. A Safe and Efficient Method for Preparation of N,N'-Unsymmetrically Disubstituted Ureas Utilizing Triphosgene
4. Hegarty, A. F. 1979.Comprehensive Organic Chemistry, Edited by: Barton, D.H. R. and Ollis, W. D. Vol. 2, 1084Oxford: Pergamon Press. one possible explanation is that the second (tertiary) basic centre in (6) induces facile conversion to the isocyanates RNCO, the ease of this transformation reflecting the relative basicities of the amines (2)-(4)
5. Alkyl 1-Chloroalkyl Carbonates: Reagents for the Synthesis of Carbamates and Protection of Amino Groups