Platinum-Catalyzed Assembly of Quinaldine from Aniline and Ethylene

Aurélien Béthegnies (1) , Pavel Dub (1) , Rinaldo Poli (1)

1 LCC - Laboratoire de chimie de coordination

The selectivity of the catalytic reaction between aniline and ethylene in the presence of the Brunet catalyst (PtBr2/Br−) shifts from the hydroamination product N-ethylaniline to the heterocyclization product 2-methylquinoline (quinaldine) when conducted in the presence of PPh3 (1 equiv per Pt atom). Condition optimization revealed that this process works best in the absence of any halide salt additive, that it is essentially insensitive to the nature of the halide in PtX2, that the best promoter in the PMexPh3−x series is PPh3 when used in strictly stoichiometric amounts, and that the 4-RC6H5NH2 (R = nBu, Cl, OMe, NMe2) substrates are equally converted albeit less efficiently. Slight dilution of the system with THF or toluene slightly improves the activity, and a kinetic profile shows the presence of an induction phase and a deactivating step, which however does not involve reduction to metallic platinum contrary to the PPh3-free Brunet catalyst. Mechanistic considerations are presented.

Mots clés: Platinum; hydroamination; quinoline synthesis; ethylene complexes; aniline; quinaldine.

Domaines: Chimie de coordination; Catalyse; Chimie organique

Aurélien Béthegnies, Pavel Dub, Rinaldo Poli. Platinum-Catalyzed Assembly of Quinaldine from Aniline and Ethylene. Organometallics, 2013, 32 (6), pp.1882-1891. ⟨10.1021/om400020k⟩. ⟨hal-02907523⟩