Intramolecular hydroamination of alkynes catalysed by late transition metals

Abstract

The cyclisation of 6-aminohex-1-yne to 2-methyl-1,2-dehydropiperidine in the presence of late transition metal catalysts was examined. The highest catalytic activity was observed for [Cu(CH₃CN)₄]PF₆, as well as with Group 12 metal salts. Slightly lower conversions were obtained with the rhodium(I) and palladium(II) complexes [Rh(COD)(DiPAMP)]BF₄ and [Pd(Triphos)][BF₄]₂. Catalysis was also observed with complexes of all group 9 to 12 metals and [Ru₃(CO)₁₂]. All catalytically active complexes contain a metal with a d⁸ or d¹⁰ electronic configuration. This observation allows preliminary conclusions about the mechanism to be made.