Pt-catalysed intermolecular hydroamination of non-activated olefins using a novel family of catalysts: Arbuzov-type phosphorus metal complexes

• P(OR)3 are promoters for the intermolecular hydroamination of α-olefins.
• Arbuzov-type metal complexes: on the origin of this promoting effect.
• Alkyl and aromatic phosphines (PR3) are inhibitors and I2 act as an antidote.
• Different coordination chemistry for PPh3, P(OPh)3 and P(OEt)3 with PtBr2.
• New X-ray structure of trans-[PtBr2(PPh3)]2 dimer.

The catalytic system “PtBr2(0.3 mol%)/2P(OR)3/10nBu4PBr” (R = alkyl) discovered recently in our group, allows good to excellent catalytic activities for the intermolecular hydroamination of ethylene and higher α-olefins (1-hexene) with aniline type amines to give the expected N-ethyl- (1) and N,N-diethyl-anilines (2) along with 2-methyl-quinoline (3). A poisoning effect of alkyl and aromatic phosphines has been observed. This effect could be minimised using small amounts of molecular iodide which reacts with phosphorus ligands to form non-coordinating well-described ionic species. Interestingly, beneficial effects of added P(OR)3 (R = alkyl) have been pointed out and further investigated. In this way, a new potential family of Arbuzov-type phosphorus-metal complexes has been suggested to be responsible for good catalytic activities found when using P(OR)3 alkyl phosphites rather than PR3 (R = alkyl, aromatic) and P(OPh)3 co-catalysts.Figure optionsDownload high-quality image (115 K)Download as PowerPoint slide

Novel family of ligands for hydroamination. Arbuzov-type phosphorus-metal complexes in situ generated from alkylphosphites and Br−, PtBr2 (0.3 mol%)/2P(OR)3/10nBu4PBr, allows good catalytic activities for the intermolecular hydroamination of ethylene and higher α-olefins (96% Markovnikov regioselectivity).Figure optionsDownload high-quality image (143 K)Download as PowerPoint slide