US EPA

6656553 

Journal Article 

Anti-Markovnikov functionalizations of unsaturated compounds, Part 5 - The first rhodium-catalyzed anti-Markovnikov hydroamination: Studies on hydroamination and oxidative amination of aromatic olefins 

Beller, M; Trauthwein, H; Eichberger, M; Breindl, C; Herwig, J; Muller, TE; Thiel, OR; , 

1999 

Yes 

Chemistry: A European Journal
ISSN: 0947-6539
EISSN: 1521-3765 

WILEY-V C H VERLAG GMBH 

BERLIN 

1306-1319 

WOS:000079645000024 

The first transition-metal-catalyzed regiospecific anti-Markovnikov hydroamination of aromatic olefins is reported. Styrene and substituted styrenes react with secondary aliphatic amines, especially morpholine and N-arylpiperazines, in the presence of cationic rhodium complexes to give 2-aminoethenylbenzene and 2-aminoethylbenzene derivatives. Cationic [Rh(cod)(2)]+BF4- and various phosphines (1:2-mixture) were employed as in situ catalysts. According to labeling experiments, there is no evidence that the hydroamination is a consecutive hydrogenation of a previously formed enamine. Hydroamination with simple secondary amines, for example piperidine, can also be achieved by the use of a higher olefin concentration and higher reaction temperatures than those given in previously published reaction procedures. Kinetic investigations of the major reaction pathway reveal that the reaction rate of the oxidative amination and the hydroamination is dependent on the styrene and on the catalyst concentration, and independent of the amine concentration. Experiments that employed deuterium-labeled amines (N-D) provided evidence that the mechanism involves an amine-activating pathway, The substituents on the styrene, the phosphine ligand, and the solvent influence the yield of the aminations and the enamine:alkylamine ratio.