Synthesis of Allyl-Terminated Polar Macromonomers by Metallocene-Catalyzed Polymerizations of 10-Undecene-1-ol

Poly­(10-undecene-1-ol) macromonomers were synthesized by metallocene-catalyzed polymerization using vinyl chloride as a chain transfer agent. Using this technique, predominantly allyl terminated polymers could be obtained, which was verified by NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). By means of the mass spectra, a detailed interpretation of the nature of the head and end groups of these polymers was possible

Formation of Oligomeric and Macrocyclic Ureas Based on 2,6-Diaminopyridine

The conversion of 1,3-bis-(6-amino-pyridin-2-yl)-urea (<b>1</b>) with <i>N</i>,<i>N</i>′-carbonyldiimidazole at high temperatures in DMSO yielded a mixture of defined cyclic trimers and tetramers. On the basis of model reactions, exchange reactions were evidenced, which convert the cyclic tetramer into a stable cyclic trimer. Linear even numbered oligomers were obtained in acetone under reflux where side reactions were suppressed. The pronounced tendency of cyclization is attributed to a preferred folded conformation of the urea bond between two pyridyl units