Ligands propane

Ligands with more that two carboxyl groups do not seem to form more stable complexes than the biscarboxylate ligands. An example is the ligand propane-1,2,3-tricarboxylate (tricarballilate) for which the equilibrium constant for the formation of the complex BeL is little greater than with succinate (76). 

Chlorides are inert. However, the reaction ofp-chlorobenzophenone (9) with a styrene derivative proceeds satisfactorily at 150 C by u.sing dippb [l,4-bis(-diisopropylphosphino)butane] as a ligand to give the stilbene derivative 10. However, dippp [l,3-bis(diisopropylphosphino)propane] is an ineffective ligand[13]. On the other hand, the coupling of chlorobenzene with styrene proceeds in the presence of Zn under base-free conditions to afford the cis-stilbene 11 as a main product with evolution of H . As the ligand, dippp is... 

Usually, iodides and bromides are used for the carbonylation, and chlorides are inert. I lowever, oxidative addition of aryl chlorides can be facilitated by use of bidcntatc phosphine, which forms a six-membered chelate structure and increa.scs (he electron density of Pd. For example, benzoate is prepared by the carbonylation of chlorobenzene using bis(diisopropylphosphino)propane (dippp) (456) as a ligand at 150 [308]. The use of tricyclohexylphosphine for the carbonylation of neat aryl chlorides in aqueous KOH under biphasic conditions is also recommended[309,310]. 

Reaction of the cyclopropyl-substituted pivalate (25) with dimethyl benzylidenema-lonate in the presence of a palladium catalyst gave a mixture of alkylidenecyclo-propane (26) and vinylcyclopropane (27). The ratio of these two adducts is found to be quite sensitive to the choice of ligand and solvent. While triisopropyl phosphite favors the formation of the methylenecyclopropane (26), this selectivity is completely reversed with the use of the bidentate phosphite ligand dptp (12). Interestingly there was no evidence for any products that would have derived from the ring opening of the cyclopropyl-TMM intermediate (Scheme 2.8) [18]. 

The regioselective arylation of butyl vinyl ether was carried out by the same group, using Pd(OAc)2 as catalyst precursor and l,3-bis(diphenylphosphino)-propane (dppp) as the ligand, dissolved in [BMIM][Bp4] (Scheme 5.2-17) [90]. 

Bidentate sulphoxides, such as 1,3-bis(methylsulphinyl)propane, 1,4-bis(methyl-sulphinyl)butane and 1,2-bis(ethylsulphinyl)ethane, have been synthesized and employed as ligands toward Mn2 +, Co2 +, Ni2 +, Cu2 + and Zn2 + 204. All metal ions are bound to the ligands via the oxygen of the sulphoxide groups and are six-coordinate, as shown in Scheme 20, with the exception of Cu2+, which is four-coordinate. 

The above-described structures are the main representatives of the family of nitrogen ligands, which cover a wide spectrum of activity and efficiency for catalytic C - C bond formations. To a lesser extent, amines or imines, associated with copper salts, and metalloporphyrins led to good catalysts for cyclo-propanation. Interestingly, sulfinylimine ligands, with the chirality provided solely by the sulfoxide moieties, have been also used as copper-chelates for the asymmetric Diels-Alder reaction. Amide derivatives (or pyridylamides) also proved their efficiency for the Tsuji-Trost reaction. 

Recently, Y. Yamamoto reported a palladium-catalyzed hydroalkoxylation of methylene cyclopropanes (Scheme 6-25) [105]. Curiously, the catalysis proceeds under very specific conditions, i.e. only a 1 2 mixture of [Pd(PPh3)4] and P(o-tolyl)3 leads to an active system. Other combinations using Pd(0 or II) precursors with P(o-tolyl)3 or l,3-bis(diphenylphosphino)propane, the use of [Pd(PPh3)4] without P(o-tolyl)3 or with other phosphine ligands were all inefficient for the hydroalkoxylation. The authors assumed a mechanism in which oxidative addition of the alcohol to a Pd(0) center yields a hydrido(alkoxo) complex which is subsequently involved in hydropal-ladation of methylenecyclopropane. 

In another context, Soai et al. have described the enantioselective cyclo-propanation of various aldehydes using dicyclopropylzinc in the presence of a catalytic amount of a chiral thiophosphoramidate ligand derived from norephedrine and Ti(Oi-Pr)4, providing the corresponding cyclopropyl alkanols with high yields and enantioselectivities of up to 97% ee (Scheme 6.24). ... 

Scheme 8.2 Hydrogenation of dehydroamino acid with thioether-phosphine cyclo-propanated ligands.

As another successful application of Noyori s TsDPEN ligand, Yan et al. reported the synthesis of antidepressant duloxetine, in 2008. Thus, the key step of this synthesis was the asymmetric transfer hydrogenation of 3-(dime-thylamino)-l-(thiophen-2-yl)propan-l-one performed in the presence of (5,5)-TsDPEN Ru(II) complex and a HCO2H TEA mixture as the hydrogen donor. The reaction afforded the corresponding chiral alcohol in both high yield and enantioselectivity, which was further converted in two steps into expected (5)-duloxetine, as shown in Scheme 9.17. 

The novel tetrabasic ligand l,3-bis(5-methylpyrazole-3-carboxamido)propane forms a trinuc-lear Co111 Co11 Co111 complex (196). The tetradentate diamide-pyrazolyl chelates encircle the terminal trivalent metal ions while the central divalent Co is in a distorted tetrahedral environment provided by the four bridging pyrazolyl rings.881... 

Catalysts of the Co(salen) family incorporating chiral centers on the ligand backbone are useful in asymmetric synthesis and the field has been reviewed.1377,1378 In two examples, the hydroxy-lation reaction (Equation (14)) involving (269) proceeds with 38% ee,1379 whereas the cyclo-propanation reaction with (271) (Equation (15)) proceeds with 75% ee and with 95 5 trans cis.1380 A Co(V) salen carbenoid intermediate has been suggested in these reactions. 

The optically pure ligands C6H5C H(Me)N(CH2CH2PPh2)2 (R)-(+)- and (A)-(-)-pnp, in the presence of [Ir(cod)(0 Mc)]2 and propan-2-ol, selectively reduce a,/3-unsaturated ketones to optically pure allylic alcohols.604... 

Reduction of Ni11 chloride complexes [NiCl2(L)] (L = various diphosphinomethanes, -ethanes, and -propanes) with, for example, potassium naphthalenide in THF gives the corresponding Ni1 chlorides [NiCl(L)].2368 By treatment of (963) with LiNHAr, a terminal amido complex of Ni1 (964) was prepared (Scheme 13).2369 It contains planar three-coordinate nickel and a planar amido ligand with d(Ni—N) = 1.881(2) A. The P,Ni,P and C,N,H planes are orthogonal with a 91° dihedral angle. 

In the homodinuclear complex [ Pd(dppp) 2(//-biim)](OTf)2 (dppp = bis(diphenylphosphino)-propane, biim = 2,2 -biimidazole, 0Tf=0S02CF3) a biim2 ligand spans the two palladium(II) centers.535... 

The synthesis, characterization, and the relative thermodynamic hydricities of hydridoplatinum(II) species-containing bidentate phosphine ligands [PtHL2]+ (L2 = dppe, depe, dmpe, l,3-bis(dimethylphosphino)propane [dmpp]) have been determined, with the best hydride donor found to be [PtH(dmpe)2]+.365... 

Thia-crown ethers incorporating propan-2-one units and dimeric silver(I) compounds as (176) and other polymeric species have been prepared.1132,1133 Other substituents can be diisopropyl idene groups which form complexes of the type [AgL(PPh3)]OTf (177),1134 pyridazine,1133 phthalazine1136 ligands or even organometallic compounds as ferrocene in (178).1137... 

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