A Cationic Gold(I) Complex as a General Catalyst for the Intermolecular Hydroamination of Alkynes: Application to the One-Pot Synthesis of Allenes from Two Alkynes and a Sacrificial Amine

A cationic gold (I) complex was reported to catalyze the addition of various types of non-tertiary amines to terminal and internal alkynes. The one-pot preparation of allenes by coupling two alkynes using a sacrificial secondary amine was also investigated. The results show that a mixture of Markovnikov and anti-Markovnikov products are obtained when methylphenylacetylene and tert-butyl-acetylene are used. It is also found that hydroamination with ammonia is a very general pre-catalyst for the addition of amines to alkynes. The coupling of two alkynes to form allenes, using an amine as a two hydrogen donor is a process that combines two distinct chemical reactions and relies on single catalyst. Gold complex is found to feature oxophilic character and display excellent functional group tolerance and low air moisture sensitivity.