Synthesis of new N-substituted chiral phosphine–phosphoramidite ligands and their application in asymmetric hydrogenations and allylic alkylations. Issue 12 (15th July 2015)

• Record Type: Journal Article
• Authors: Balogh, Szabolcs; Farkas, Gergely; Tóth, Imre; Bakos, József
• Is Part Of: Tetrahedron, asymmetry. Volume 26:Issue 12/13(2015)
• Page Start: 666
• Page End: 673
• Publication Date: 2015-07-15
• Subjects: Asymmetry (Chemistry) -- Periodicals; 547.005
• DOI: 10.1016/j.tetasy.2015.05.001
• Languages: English
• ISSNs: 0957-4166

Abstract

Graphical abstract: Abstract: Phosphine–phosphoramidite ligands containing a 2, 4-pentanediyl backbone, BINOL moieties, and Me, Bn or Ph substituent on the nitrogen were synthesized and fully characterized. The electronic effect of the N -substituents was examined by 31 P NMR of their corresponding seleno-phosphate-amide and phosphine–selenide derivatives. The new ligands together with their earlier reported derivatives were tested in the palladium catalyzed asymmetric allylic alkylation of rac -( E )-1, 3-diphenylallyl acetate. Remarkably high activity (up to 1780 h −1 turnover frequency) and first order kinetics were observed by facilitating nucleophile formation. The substituent at the nitrogen and the configuration of chiral moieties had a high impact on the enantioselectivity. The new ligands were also tested in the rhodium-catalyzed asymmetric hydrogenation of methyl ( Z )-α-acetamidocinnammate, dimethyl itaconate (up to 99.9% ee's) and methyl 2-acetamidoacrylate (up to 99.5% ee). Abstract : (11b S )- N -((2 S, 4 S )-4-(Diphenylphosphino)pentan-2-yl)- N -benzyl-{dinaphtho[2, 1- d :1′, 2′- f ][1, 3, 2]dioxaphosphepin-2-yl}-4-amine: C44 H39 NO2 P2 [ α ]D 20 = +129.2 ( c 1, CH2 Cl2 ) Source of chirality: ( S )-H0 -BINOL, (2 R, 4 R )-pentane-2, 4-diol and stereoselective synthesis Abstract : (11b S )- N -((2 S, 4 S )-4-(Diphenylphosphino)pentan-2-yl)- N -phenyl-{dinaphtho[2, 1- d :1′, 2′- f ][1, 3, 2]dioxaphosphepin-2-yl}-4-amine: C43 H37 NO2 P2 [ α ]D 20 = +89.4 ( c 1, CH2 Cl2 ) Source of chirality: ( S )-H0 -BINOL, (2 R, 4 R )-pentane-2, 4-diol and stereoselective synthesis Abstract : (11b S )- N -((2 S, 4 S )-4-(Diphenylphosphino)pentan-2-yl)- N -methyl-{dinaphtho[2, 1- d :1′, 2′- f ][1, 3, 2]dioxaphosphepin-2-yl}-4-amine: C38 H35 NO2 P2 [ α ]D 20 = +244.2 ( c 1, CH2 Cl2 ) Source of chirality: ( S )-H0 -BINOL, (2 R, 4 R )-pentane-2, 4-diol and stereoselective synthesis