Palladium(II) 3-iminophosphine (3IP) complexes: Active precatalysts for the intermolecular hydroamination of 1,2-dienes (allenes) and 1,3-dienes with aliphatic amines under mild conditions

The synthesis of alicyclic 3-iminophosphine ligands is extended to include a new framework incorporating a cyclohexenyl backbone with an N-aryl imino functionality (3IPAr). Accordingly, a series of palladium(II) complexes employing this new ligand have been synthesized and utilized in the intermolecular hydroamination of 3-methyl-1,2-butadiene (1,1-dimethylallene) and 2,3-dimethyl-1,3-butadiene with secondary amines. The complex [(3IPAr)Pd(allyl)]OTf displays excellent catalytic activity in these reactions, selectively producing allylic amine products in high conversion under mild conditions, with an improved rate relative to that observed for our previously reported catalysts. Further, the reactivity trends for the (3IP)Pd triflate systems prove to be complimentary to other known late transition metal based catalytic systems.

Graphical abstractA new 3-iminophosphine ligand incorporating a cyclohexenyl backbone with an N-aryl imino functionality was used to produce a series of palladium(II) complexes. The complex of the form [LPd(allyl)][O3SCF3] displayed excellent catalytic activity for the intermolecular hydroamination of 3-methyl-1,2-butadiene and 2,3-dimethyl-1,3-butadiene with secondary amines, selectively producing allylic amine products in high conversion under mild conditions.Figure optionsDownload full-size imageDownload as PowerPoint slide