New chiral diphosphoramidite rhodium(I) complexes for asymmetric hydrogenation

作者：Drommi Dario; Micalizzi Giuseppe; Arena Carmela Grazia^*

来源：Applied Organometallic Chemistry, 2014, 28(8): 614-619.

DOI：10.1002/aoc.3170

• diphosphoramidite
• asymmetric hydrogenation
• rhodium
• hydrogen pressure

Chiral 1,5-cyclooctadiene rhodium(I) cationic complexes with C-2-symmetric chelate diphosphoramidite ligands containing (R,R)-1,2-diaminocyclohexane as the backbone and two atropoisomeric biaryl units were easily synthesized and fully characterized by multinuclear one- and two-dimensional NMR spectroscopy and elemental analysis. These complexes were used as catalysts in the asymmetric hydrogenation of dimethyl itaconate, methyl 2-acetamidoacrylate and (Z)-methyl-2-acetamido-3-phenylacrylate. The rhodium complexes derived from diphosphoramidite ligands that contain two (R) or (S) BINOL (2,2%26apos;-dihydroxy-1,1%26apos;-binaphthyl) units proved to be efficient catalysts, giving complete conversion and very good enantioselectivity (up to 88% ee). An uncommon positive H-2 pressure effect on the enantioselectivity was observed in the hydrogenation of dimethyl itaconate catalyzed by Rh-complex with diphosphoramidite ligand that contains two (S)-binaphthol moieties.

• 出版日期2014-8