Ligands preparation

Since Evans s initial report, several chiral Lewis acids with copper as the central metal have been reported. Davies et al. and Ghosh et al. independently developed a bis(oxazoline) ligand prepared from aminoindanol, and applied the copper complex of this ligand to the asymmetric Diels-Alder reaction. Davies varied the link between the two oxazolines and found that cyclopropyl is the best connector (see catalyst 26), giving the cycloadduct of acryloyloxazolidinone and cyclopentadiene in high optical purity (98.4% ee) [35] (Scheme 1.45). Ghosh et al., on the other hand, obtained the same cycloadduct in 99% ee by the use of unsubstituted ligand (see catalyst 27) [36] (Scheme 1.46, Table 1.19). 

Cyanato-copper(II) complexes with nitrogen organic ligands preparation, properties and structure. J. Kohout, M. Hvastijova and J. Gazo, Coord. Chem. Rev., 1978, 27,141-172 (116). 

Minghetti, G., BanditeDi, G. and Bonati, E. (1979) Metal derivatives of azoles. 3. The pyrazolato anion (and homologs) as a mono- or bidentate ligand preparation and reactivity of tri-, hi-, and mononudear... 

In 1991, Helmchen et al. studied this reaction in the presence of C2-symmetric bis(thiazolines) ligands prepared in a few simple steps from amino acids and... 

Strategies for selective partial alkylation of cyclam have been developed and Ni11 complexes of the variously substituted ligands prepared.1489 In a series of tetra-A-alkylated cyclams, Ni11 incorporation was only observed for smaller substituents such as Me, Et, and Pr, while no... 

The ligands prepared by this method were sufficiently pure for use as an in situ catalyst preparation. 

Figure 13. Ligands prepared from bis[2-(diphenylphosphino)cthyljamine...

A series of optically active linear tetradentate ligands, which have been stereospeeifically synthesized, have been used to prepare complexes with a trans-[CoN Cl2] core and both five- and six-membered chelate rings, in an attempt to correlate the sign of the Cotton effect with the known chiralities of compounds. How ever, a complete correlation was not possible. The synthesis, resolution, and properties of some oxalato, malonato, and diacido complexes of Co " with the stereospecific flexible tetramine ligands 5-Me-3,2,3-tet and NA -bis-(2-picoyl)-l-methyl-1,2-diaminoethane (picpn) have been reported. The stereospecificity is demonstrated by comparison of the optical rotation of the ligand prepared via an asymmetric synthesis with that of the ligand isolated from a resolved complex. The stereochemistry of the complexes has been deduced. ... 

Ruthenium has a considerable propensity to form polynuclear complexes, particularly with carboxylate ligands which as bridging ligands span the Ru centres, sometimes accompanied by a bridging 0x0 ligand. Preparation and properties of bi- and tri-nuclear acetato complexes of Ru have been reviewed [552]. 

Figure 7.6 Structure of a bent ditopic ligand prepared by Wang et al. (2005) and a schematic representation of a metal-templated macrocycle.

C. Halldin, T. Hogberg, L. Farde, Fluorine-18-labeled NCQ 115, a selective dopamine D-2 receptor ligand. Preparation and positron emission tomography, Nucl. Med. Biol. 21 (1994) 627-631. 

Both pyrimidine and quinazoline derivatives have been investigated as ligands for palladium-mediated reactions. Examples of ligands prepared include the phosphine-free bipyrimidine 1181, which gave the isolable palladium dichloride catalyst 1182 <2001JOM(634)39>, and the chiral oxazolinyl-quinazoline BINAP analogs 1183 and 1184 <20060L5109>. 

Immobilized ligands prepared by the divinylsulfone method are unstable above pH 8.0. 

Asymmetric hydrovinylation.1 The reaction of ethylene with 1,3-cyclohex-adiene catalyzed by bis(l,5-cyclooctadiene)nickel, diethylaluminum chloride, and 1 gives ( + )-(S)-3-vinyl-l-cyclohexene (2) in quantitative yield and 93% ee. Related ligands prepared from (S)-proline and D-ephedrine are less effective for asymmetric hydrovinylation. 

Complexes such as (62) can be submitted to hydrogenation and oxidative dehydrogenation processes of the type already described for related systems. The most interesting investigation has actually been carried out on complexes of a tetramethyl substituted ligand prepared from a nontemplate reaction sequence. In particular, oxidative dehydrogenation affords macrocyclic chro-mophores with six and seven double bonds (Scheme 24).118,141... 

Monoiminophosphines. As illustrated in Scheme II, PCHO condenses with a wide variety of simple and functionalized monoamines. Studies of the Mo(O) derivatives of several of these ligands demonstrate that they efficiently displace CO from Mo(CO)e affording (chel)Mo(CO)4 or fac-(chel)Mo(CO)3 derivatives (4). Similar, but bimetallic, complexes can be obtained from the ligands prepared by condensations with nonchelating diamines such as m- or p-diaminobenzene. 

Many exotic electrophiles have been shown to react with co-ordinated thiolate for example new disulfide bonds may be formed by reaction with S2C12. The nickel(n) complex of a very unusual tetrasulfide macrocyclic ligand may be prepared by this method (Fig. 5-83). Notice that this reaction utilises the nickel complex of the N2S2 ligand prepared by a metal-directed reaction in Fig. 5-78. 

CoCp unit C-C bond activation, 7, 80 CoCp unit CH activation, 7, 79 in ethylene polymerization, 7, 81 substituted ligands, 7, 71 synthetic applications, 7, 74 with )4-cyclobutadiene applications, 7, 66 new ligand preparation, 7, 70 with )4-(cyclobutadiene) ligands, 7, 59 dendrimeric cobaltocenium derivatives, 7, 88 with fullerenes, 7, 51 HP-NMR and HP-IR studies, 1, 488 with rj -hydrocarbyl units, 7, 8 immobilized, as polymer support, 12, 681 kinetic studies, 1, 520 with )3-ligands, 7, 56 with metallaboranes, 3, 158 overview, 7, 1-119... 

Crown-5-triarylphosphine hybrid ligand, preparation, 8, 2 Crystal engineering... 

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