Benzoannelated Fenestranes

Kuck D. Benzoannelated Fenestranes. In: Thummel RP, ed. Advances in Theoretically Interesting Molecules. 4. Greenwich, London: JAI Press; 1998: 81-155

Chiral 2,2'-Bipyridines, 1,10-Phenanthrolines, and 2,2':6',2''-Terpyridines: syntheses and applications in asymmetric homogeneous catalysis

Although chiral phosphines have enjoyed a longtime popularity in the design of enantioselective catalytic systems, there has been a recent renaissance in the use of nitrogen ligands for this same purpose.1 This renaissance partly arises from several distinct advantages presented by nitrogen-containing ligands. First, they can often be employed in catalytic processes where the use of phosphines may be incompatible with the reaction conditions. Second, many nitrogen ligands are now available in enantiomerically pure form. Third, ligands that bind through nitrogen are known to coordinate with a wide variety of metal ions, and considerable progress has been made in understanding the role which these ligands play in affecting catalytic processes

Polydentate Analogues of 8-Hydroxyquinoline and Their Complexes with Ruthenium

Selective reduction of 2-nitro-3-methoxybenzaldehyde provides 2-amino-3-methoxybenzaldehyde that undergoes the Friedländer condensation with a variety of acetyl-substituted derivatives of pyridine and 1,10-phenanthroline. After cleavage of the methyl ether, the resulting polydentate analogues of 8-hydroxyquinoline are excellent ligands for ruthenium. The resulting oxidation state of the metal center depends on the anionic character of the ligands. The presence of two electron donating anionic ligands results in a Ru(III) complex as evidenced by paramagnetic NMR behavior. The electronic absorption and redox properties of the complexes were measured and found to be consistent with the anionic character of the 8-HQ moieties. A planar pentadentate ligand provides two Ru–O and two Ru–N bonds in the equatorial plane. An X-ray structure shows that the central pyridine of the ligand is oriented toward the metal but held at a distance of 2.44 Å