Insertion of phenyl isocyanide into ethanol catalysed simultaneously by copper(I) and base

Abstract

Abstract The insertion of phenyl isocyanide into ethanol under the influence of base and Cu(PhNC) 4 BF 4 is investigated mechanistically. In pre‐equilibria the BF 4 ⊖ anion is exchanged for ⊖ OC 2 H 5 . By intramolecular nucleophilic attack of ⊖ OC 2 H 5 on coordinated isocyanide an [(ethoxy)‐(phenylimino)methyl]copper intermediate is formed. The substituent effect supports this conclusion. In a rapid reaction with ethanol the intermediate decomposes and the insertion product, ethyl N ‐phenylformimidate, is formed. It reacts slowly to give N,N′ ‐diphenylformamidine, which is precipitated at the end of the reaction as a copper complex.