Another route towards the synthesis of poly(dichlorophosphazene) involves the condensation polymerization of Cl3P=N-P(O)Cl2. Some molecular weight control is achieved, but drawbacks include the necessity for high temperatures, the production of corrosive side products and high polydispersities (PDI > 2).
Routes are also available for the direct synthesis of poly(alkyl/aryl)phosphazenes via the condensation polymerization of N-silylphosphoranimines at 200°C, developed by Neilson and Wisian-Neilson, which gives moderate molecular weight polymers (Mn ~ 105) with polydispersity indices of 1.5-3.0.
An efficient method for palladium-catalyzed cross-coupling of aryl chlorides and triflates with sodium cyanate is reported. The protocol allows for the synthesis of unsymmetrical N,N'-di- and N,N,N'-trisubstituted ureas in one pot and is tolerant of a wide range of functional groups. Insight into the mechanism of aryl isocyanate formation was gleaned through studies of the transmetalation and reductive elimination steps of the reaction, including the first demonstration of reductive elimination from an arylpalladium isocyanate complex to produce an aryl isocyanate.
ChemInform Abstract: Synthesis of 8-Aryl-Substituted …
The revival of a nearly 50-year-old technique for forming carbon-carbon bonds may help ease the synthesis of aryl derivatives, such as drug candidates.