Researchers in America have employed a gold catalyst in the intramolecular hydroamination of unactivated C=C bonds with alkylamines. 

Hydroamination involves the addition of an N-H bond across a C-C multiple bond. This is a highly atom economical method of preparing nitrogen heterocycles which are attractive targets for organic synthesis and the pharmaceutical industry. 

The hydroamination of unactivated C=C bonds is very challenging and the properties of the catalysts have until now limited the synthetic utility of the procedure. The catalysts have shown excessive oxophilicity and/or basicity. Late transition metal catalysts have recently overcome the problem of oxophilicity but hydroamination reactions of primary and secondary aliphatic amines are still rare and have not been previously reported with gold-derived catalyst systems. 

Ross Widenhoefer and Christopher Bender from Duke University, USA, have now used a gold(I) catalytic mixture to drive the intramolecular hydroamination of unactivated C=C bonds with primary and secondary ammonium salts. They used a catalytic 1:1 mixture of  (5)AuCl {5 = PCy₂[2-(2,6-C₆H₃(OMe)₂)C₆H₄]}  and AgOTf in toluene at 80 ^oC. The combined use of ammonium salts and toluene solvent provides superior results to those obtained with free amines or other solvents. 

Kathryn Sear