104637-11-8Relevant articles and documents
A novel P-chirogenic phosphine ligand, (S,S)-1,2-bis-[(ferrocenyl)methylphosphino]ethane: Synthesis and use in rhodium-catalyzed asymmetric hydrogenation and palladium-catalyzed asymmetric allylic alkylation
Oohara, Nobuhiko,Katagiri, Kosuke,Imamoto, Tsuneo
, p. 2171 - 2175 (2003)
A new P-chirogenic diphosphine ligand, (S,S)-1,2-bis[(ferrocenyl)methylphosphino]ethane, was prepared via phosphine-borane intermediates. The ligand was used in the rhodium-catalyzed asymmetric hydrogenation of dehydroamino acid derivatives (up to 77% ena
Atropselective Dibrominations of a 1,1′-Disubstituted 2,2′-Biindolyl with Diverging Point-to-Axial Asymmetric Inductions. Deriving 2,2′-Biindolyl-3,3′-diphosphane Ligands for Asymmetric Catalysis
Baumann, Thomas,Brückner, Reinhard
supporting information, p. 4714 - 4719 (2019/03/26)
On the 1H NMR timescale, 2,2′-biindolyls with (R)-configured (1-alkoxyprop)-2-yl, (1-hydroxyprop)-2-yl, or (1-siloxyprop)-2-yl substituents at C-1 and C-1′ are atropisomerically stable at 30 °C. A 2,2′-biindolyl (R,R)-17 a of that kind and achiral (!) brominating reagents gave the atropisomerically stable 3,3′-dibromobiindolyls (M)- and/or (P)-18 a at best atropselectively—because of point-to-axial asymmetric inductions—and atropdivergently, exhibiting up to 95 % (M)- and as much (P)-atropselectivity. This route to atropisomerically pure biaryls is novel and should extend to other substrates and/or different functionalizations. The dibromobiindolyls (M)- and (P)-18 a furnished the biindolyldiphosphanes (M)- and (P)-14 without atropisomerization. These syntheses did not require the resolution of a racemic mixture, which distinguishes them from virtually all biaryldiphosphane syntheses known to date. (M)- and (P)-14 acted as ligands in catalytic asymmetric allylations and hydrogenations. Remarkably, the β-ketoester rac-25 c was hydrogenated trans-selectively with 98 % ee; this included a dynamic kinetic resolution.
Enantioselective zinc-mediated conjugate addition of terminal alkynes to enones
Blay, Gonzalo,Cardona, Luz,Pedro, Jose R.,Sanz-Marco, Amparo
supporting information, p. 12966 - 12969,4 (2012/12/12)
Zinc for conjugate alkynylation: The enantioselective conjugate addition of terminal alkynes to 2-arylidene-1,3-diketones in the presence of diethylzinc and a catalytic amount of (R)-VANOL has been developed. The reaction can be applied to different aromatic and heteroaromatic alkynes and enones, giving the expected products in good yield and with enantiomeric excesses up to 91 %. The products can be enantiomerically enriched up to 99 % ee by crystallization (see scheme). Copyright
