title: Rhodium phosphine-phosphite catalysts in the hydrogenation of challenging N-(3,4-dihydronaphthalen-2-yl) amide derivatives.
abstract: The enantioselective catalytic hydrogenation of N-(3,4-dihydronaphthalen-2-yl) amides (1) with rhodium catalysts bearing phosphine-phosphite ligands 4 has been studied. A wide catalyst screening, facilitated by the modular structure of 4, has found a highly enantioselective catalyst for this reaction. This catalyst gives a 93% ee in the hydrogenation of 1a and also produces high enantioselectivities, ranging from 83 to 93% ee, in the hydrogenation of several OMe- and Br-substituted substrates. In contrast, the structurally related enol esters 2 are very reluctant to undergo hydrogenation. A coordination study of the representative enamide 1d has shown an unusual η(6)-arene coordination mode, over the typical O,C,C chelating mode for enamides, as the preferred one for this substrate in a Rh(I) complex. Deuteration reactions of 1c,d indicate a clean syn addition of deuterium to the double bond without an isotopic effect on the enantioselectivity.
authors.affiliation: Instituto de Investigaciones Químicas, CSIC and Universidad de Sevilla, Avda Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain.
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Arribas
authors.forename: Miguel
authors.initials: M
authors.lastname: Rubio
authors.forename: Patryk
authors.initials: P
authors.lastname: Kleman
authors.forename: Antonio
authors.initials: A
authors.lastname: Pizzano
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives* / Q000737:chemistry; D006865:Hydrogenation; D008024:Ligands; D015394:Molecular Structure; D010720:Phosphines / Q000737:chemistry*; D017905:Phosphites / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D008024:Ligands; C582739:N-(3,4-dihydronaphthalen-2-yl)amide; D010720:Phosphines; D017905:Phosphites; D015081:2-Naphthylamine; D012238:Rhodium