Renovation of Optically Active Phenanthrolines as Powerful Chiral Ligands for Versatile Asymmetric Metal Catalysis

Abstract

In the field of asymmetric synthesis, the development of new chiral ligands has been regarded as an attractive challenge for decades. Novel chiral ligands can often have a great impact on synthetic protocols. In this context, we are currently interested in the application of 1,10-phenanthroline (phen) as an entirely new class of chiral ligand. To handle this issue, we designed a chiral phen ligand that provides the N,N,O-tridentate coordination of the phen moiety and an additional phenolic hydroxyl group. As phen possesses greater coordination ability with various ions, our chiral phen ligand would be valuable as one of the "privileged" chiral ligands applied to a broad range of metal catalysts and new reactions. This account summarizes the results of the application of the chiral phen ligand to various kinds of metal catalysis.

Phosphoric Acid-Catalyzed Alkene Difunctionalization of 2-Vinylpyridines via HOMO/LUMO Biactivated Diels–Alder Reaction

“…1 H NMR (400 MHz, CDCl 3 ) δ 8.82 (s, 1H), 8.48−8.47 (m, 1H), 7.65−7.61 (m, 1H), 7.19 (d, J = 8.0 Hz, 1H), 7.17−7.14 (m, 1H), 7.06 (d, J = 8.0 Hz, 1H), 6.97 (t, J = 7.2 Hz, 1H), 6.78 (d,J = 7.2 Hz,1H),4.42 (dd,J = 11.6,4.9 Hz, 1H), 3.75 (s, 3H), 3.51 (dd, J = 15.4, 5.2 Hz, 1H), 3.24−3.16 (m, 1H), 3.01−2.93 (m, 1H), 2.68 (s, 3H), 2.63 (dd, J = 12.4, 5.2 Hz, 1H), 2.14 (q, J = 12.5 Hz, 1H). 13 C { 1 H} NMR (101 MHz, CDCl 3 ) δ: 175.8, 162.3, 149.1, 137.2, 136.3, 133.4, 130.4, 126.1, 122.2, 121.7, 120.5, 109.8, 108.7, 52.0, 42.9, 41.1, 33.1, 26.9, 20.0 cis- 3,4,. Flash column chromatography was performed on silica gel (eluent: PE/EtOAc = 8/1 to 4/1 v/v) to afford 3f.…”

“…7, 153.6, 153.1, 135.3, 135.2, 133.4, 126.1, 120.9, 120.6, 120.5, 118.1, 117.0, 109.8, 108.1, 54.5, 50.8, 41.0, 39.7, 32.9, 23.3. HRMS (ESI-ion trap) m/z: [M + H] + calcd for C 20 H 21 N 2 O 3 337.1547; found: 337.1544 cis- 3,4,. Flash column chromatography was performed on silica gel (eluent: PE/EtOAc = 4/1, v/v) to afford 3p.…”

First Trifluoromethylated Phenanthrolinediamides: Synthesis, Structure, Stereodynamics and Complexation with Ln(III)

“…The high coordinating ability of phenanthroline derivatives towards transition metals made them attractive platforms on which the coordinated metal can serve as a Lewis acid binding site for various substrates. That is why functionally substituted phenanthrolines are increasingly used in asymmetric catalysis (see reviews [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]). In recent years, a large number of lanthanoid and rare-earth elements complexes with chiral donor ligands have been obtained [ 13 , 14 , 15 ].…”

Phen-2NO, a new C2-symmetric rigid-featured tetradentate ligand, and its application in the asymmetric alkylation reaction of indoles

“…As phenanthroline possesses great coordination ability with various ions, to achieve high efficiency of chirality multiplication, the design and effective synthesis of privileged chiral phenanthroline is the most attractive strategy. 3,4 In this context, C 1 -symmetric chiral phenanthroline ligands (Scheme 1a), 4 serving as N , N -bidentate ligands, have gained considerable attention in some asymmetric catalytic reactions. Some elegant strategies, which are mainly based on the attachment of pendent chiral auxiliaries at the C-2 or C-3 positions of the phen backbone, have been developed to access chiral phen scaffolds.…”

“…However, high prices and tedious preparation methods pose severe limitations to the application of the classical N , N -bidentate phen ligands. 3–5…”