116692-85-4Relevant articles and documents
Asymmetric Reductive Amination of Cycloalkanones, 2. Synthesis and Absolute Configuration of 2-Substituted Cyclohexanamines
Knupp, Gerd,Frahm, August W.
, p. 2076 - 2098 (2007/10/02)
Asymmetric synthesis of 2-substituted cyclohexanamines from racemic cyclohexanones by means of reductive amination in a three-step procedure is described.Condensation of the ketones 5 with the optically active auxiliary amines 6 leads to the imines 7, which are hydrogenated to the secondary amines 8 with Raney nickel.Hydrogenolysis with palladium-on-charcoal yields the primary amines 9.With Raney nickel as catalyst the synthesis of the amines 8 and 9 runs with high chemical yield under complete diastereomeric and high grade enantiomeric control, respectively.Enantiomeric excess is determined via the diastereomeric acylamines 10 by means of HPLC.Stereochemical analysis including the absolute configuration of 8 and 9 is performed with 1H, 13C NMR spectroscopy, via the CD of the salicylidenes 11 and the X-ray spectrum of the amine 9c. - Reaction mechanism is investigated via the partially deuterated amine 13 to come up as a kinetically controlled asymmetric hydrogenation combined with a thermodynamically controlled transformation.