128113-70-2Relevant academic research and scientific papers
Development of an asymmetric trimethylenemethane cycloaddition reaction: Application in the enantioselective synthesis of highly substituted carbocycles
Trost, Barry M.,Silverman, Steven M.,Stambuli, James P.
supporting information; experimental part, p. 19483 - 19497 (2012/01/06)
A protocol for the enantioselective [3+2] cycloaddition of trimethylenemethane (TMM) with electron-deficient olefins has been developed. The synthesis of novel phosphoramidite ligands was critical in this effort, and the preparation and reactivity of these ligands is detailed. The evolution of the ligand design, commencing with acyclic amine-derived phosphoramidites and leading to cyclic pyrrolidine and azetidine structures, is discussed. The conditions developed to effect an asymmetric TMM reaction using 2-trimethylsilylmethyl allyl acetate were shown to be tolerant of a wide variety of alkene acceptors, providing the desired methylenecyclopentanes with high levels of enantioselectivity. The donor scope was also explored, and substituted systems were tolerated, including one bearing a nitrile moiety. These donors were reactive with unsaturated acylpyrroles, giving the product cyclopentane rings bearing three stereocenters in high enantioselectivity and complete diastereoselectivity.
Chiral Building Blocks for the Synthesis of Nitrogen-Containing Natural Products, 5. The Enantioselective Synthesis of Optically Active, Benzene Nucleus-Substituted 1-Phenylethylamines from the Corresponding Acetophenones
Bringmann, Gerhard,Geisler, Joerg-Peter,Geuder, Torsten,Kuenkel, Georg,Kinzinger Lioba
, p. 795 - 805 (2007/10/02)
An efficient two-step procedure for the synthesis of enantiomerically pure, benzene nucleus-substituted 1-phenylethylamines 1 is described, with predictable absolute configuration at the stereogenic center: Imine formation from the substituted acetophenones 6 with (S)- or (R)-1-phenylethylamine and subsequent hydrogenation of the resulting Schiff bases 8 over Raney nickel leads to the secondary amines 9 and 10 in high diastereoselectivities.These dibenzylamines are cleaved regioselectively, usually next to the less substituted aromatic ring, giving the desired chiral 1-phenylethylamines 1 in high yields and enantiomeric purities.Scope and limitations of this new and facile approach to the versatile building blocks 1 are reported.
