AUTHOR=Sirignano Marco , D’Amato Assunta , Costabile Chiara , Mariconda Annaluisa , Crispini Alessandra , Scarpelli Francesca , Longo Pasquale 

TITLE=Hydroamination of alkynes catalyzed by NHC-Gold(I) complexes: the non-monotonic effect of substituted arylamines on the catalyst activity

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1260726

DOI=10.3389/fchem.2023.1260726

ISSN=2296-2646

ABSTRACT=<p>Imines are valuable key compounds for synthesizing several nitrogen-containing molecules used in biological and industrial fields. They have been obtained, as highly regioselective Markovnikov products, by reacting several alkynes with arylamines in the presence of three new N-Heterocyclic carbene gold(I) complexes (<bold>3b</bold>, <bold>4b,</bold> and <bold>6b</bold>) together with the known <bold>1-2b</bold> and <bold>7b</bold> gold complexes as well as silver complexes <bold>1-2a</bold>. Gold(I) complexes were investigated by means of NMR, mass spectroscopy, elemental analysis, and X-ray crystallographic studies. Accurate screening of co-catalysts and solvents led to identifying the best reaction conditions and the most active catalyst (<bold>2b</bold>) in the model hydroamination of phenylacetylene with aniline. Complex <bold>2b</bold> was then tested in the hydroamination of alkynes with a wide variety of arylamines yielding a lower percentage of product when arylamines with both electron-withdrawing and electron-donating substituents were involved. Computational studies on the rate-determining step of hydroamination were conducted to shed light on the significantly different yields observed when reacting arylamines with different substituents.</p>