Imines catalysts for

Weissman H, Milstein D (1999) Highly active Pdn cyclometallated imine catalyst for the Suzuki reaction. Chem Commun 1901-1902... 

Ohff, M. Ohff, A. Milstein, D. Highly active Pd(II) cyclometalated imine catalysts for the Heck reaction. Chem. Commun. 1999, 357-358. 

Ligands with coordinating N-O atoms phenoxy-imine-catalysts for polyethylene 1096... 

This area of research has only recently attracted the attention of synthetic organic chemists, but there has been a flurry of impressive activity in the area. Simple (i. e., unstabilized) carbenes suffer from many of the problems of nitrenes (vide infra) and most reported synthetically useful procedures use carbenoids the majority of recent reports have focussed upon reactions between a-diazoesters and imines in the presence of a range of catalysts. In one of the earliest reports of enantioselective carbene-imine reactions, for instance, Jacobsen and Finney reported that ethyl diazoacetate reacts with N-arylaldimines in the presence of cop-per(i) hexafluorophosphate with mediocre stereoselectivity to give N-arylaziridine carboxylates. Though the diastereoselectivities of the reaction were often acceptable (usually >10 1, in favor of the cis isomers) the observed enantioselectivity was low (no more than 44% ee Scheme 4.27) [33],... 

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. 

Scheme 5 FeCls as efficient catalyst for reactions of electron-rich arenes with imines or aziridines...

In 1997 the first asymmetric aza-Claisen rearrangement was reported by Overman et al. [55], which made use of diamines as bidentate ligands for Pd(II), allowing for moderate enantioselectivities. In the same year, Hollis and Overman described the application of the planar chiral ferrocenyl palladacycle 38 as a catalyst for the enantioselective aza-Claisen rearrangement of benzimidates 39 (Fig. 19) [56]. A related ferrocenyl imine palladacycle provided slightly inferior results, while a benzylamine palladacycle lacking the element of planar chirality was not able to provide any enantioselectivity [57]. 

Cohen F, Overman LE (1998) Planar-chiral cyclopalladated ferrocenyl amines and imines as enantioselective catalysts for allylic imidate rearrangements. Tetrahedron Asymmetry 9 3213-3222... 

In addition, the same group has used copper complexes of these ligands as efficient catalysts for enantioselective Cu-catalysed aza-Diels-Alder reactions of A-sulfonyl imines with Danishefsky s dienes, providing the corresponding six-membered heterocycles with enantioselectivities of up to 80% ee. ... 

Optically active /3-ketoiminato cobalt(III) compounds based on chiral substituted ethylenedi-amine find use as efficient catalysts for the enatioselective hetero Diels Alder reaction of both aryl and alkyl aldehydes with l-methoxy-(3-(t-butyldimethylsilyl)oxy)-1,3-butadiene.1381 Cobalt(II) compounds of the same class of ligands promote enantioselective borohydride reduction of ketones, imines, and a,/3-unsaturated carboxylates.1382... 

Pr(H2)CPPh3)2(solv)2]+ catalysts for imine hydrogenation have been kinetically explored. This area is notably less developed than the reduction of C=0 bonds.88,110... 

As with hydrogenation, hydrogen transfer of imines is a poorly developed field.126-130 However, recent arene-Ru11 systems bearing chiral 1,2-diamine co-ligands have been found to be excellent catalysts for asymmetric reduction of imines with formic acid as donor.31,131-134... 

Among the most active catalysts for the asymmetric transfer hydrogenation of prochiral ketones and imines to chiral alcohols and amines are arene-ruthenium(II) amino-alcohol (or primary/ secondary 1,2-diamine)-based systems, with an inorganic base as co-catalyst, developed by Noyori139-141 and further explored by others (Scheme 27).142-145... 

Prochiral imines can be hydrogenated to the corresponding amines with extremely high enan-tioselectivities in H20/ethyl ethanoate biphasic systems, using Rh1 complexes of sulfonated phosphines 342 The cationic rhodium complex [Rh(NBD)(131)]+ was an active catalyst for hydrogenation of 2-ethanamido-propenoic acid in aqueous solution.343... 

Rare-earth-metal triflates are efficient catalysts in Diels-Alder reactions, and Sc(OTf)3 is clearly more effective than Ln(OTf)3 as a catalyst.45,53-55 In the presence of 10mol.% Y(OTf)3 or Yb(OTf)3, only a trace amount of the adduct was obtained in the Diels-Alder reaction of methyl vinyl ketone (MVK) with isoprene. In contrast, the reaction proceeded smoothly to give the adduct in 91% yield in the presence of 10mol.% Sc(OTf)3 (Scheme 13).45 Sc(OTf)3 has also proved to be an efficient catalyst for the Diels-Alder reaction of imines (aza Diels-Alder reactions).56,57... 

In this contribution, we describe the discovery and application of phenoxy-imine ligated early transition metal complexes (FI catalysts) for olefin polymerization, including the concept behind our catalyst design, the discovery and the polymerization behavior of FI catalysts, and their applications to new polyolefinic materials. 

The isopropyl group discourages P-H transfer, leading to the exclusive formation of Al-PEs. The Al-PEs can be readily transformed to a variety of functionalized PEs and to PE-based and polar polymer-based block and graft copolymers, using established methods. The selective synthesis of vinyl- and Al-terminated PEs with Zr-FI catalysts shows the critical importance of the substituent on the imine-N for polymerization catalysis. 

Beyond palladium, it has recently been shown that isoelectronic metal complexes based on nickel and platinum are active catalysts for diyne reductive cyclization. While the stoichiometric reaction of nickel(O) complexes with non-conjugated diynes represents a robust area of research,8 only one example of nickel-catalyzed diyne reductive cyclization, which involves the hydrosilylative cyclization of 1,7-diynes to afford 1,2-dialkylidenecyclohexanes appears in the literature.7 The reductive cyclization of unsubstituted 1,7-diyne 53a illustrates the ability of this catalyst system to deliver cyclic Z-vinylsilanes in good yield with excellent control of alkene geometry. Cationic platinum catalysts, generated in situ from (phen)Pt(Me)2 and B(C6F5)3, are also excellent catalysts for highly Z-selective reductive cyclization of 1,6-diynes, as demonstrated by the cyclization of 1,6-diyne 54a.72 The related platinum bis(imine) complex [PhN=C(Me)C(Me)N=Ph]2Pt(Me)2 also catalyzes diyne hydrosilylation-cyclization (Scheme 35).72a... 

Palmer and Wills in 1999 reviewed other ruthenium catalysts for the asymmetric transfer hydrogenation of ketones and imines [101]. Gladiali and Mestro-ni reviewed the use of such catalysts in organic synthesis up to 1998 [102]. Review articles that include the use of ruthenium asymmetric hydrogenation catalysts cover the literature from 1981 to 1994 [103, 104], the major contributions... 

Early transition-metal complexes have been some of the first well-defined catalyst precursors used in the homogeneous hydrogenation of alkenes. Of the various systems developed, the biscyclopentadienyl Group IV metal complexes are probably the most effective, especially those based on Ti. The most recent development in this field has shown that enantiomerically pure ansa zirconene and titanocene derivatives are highly effective enantioselective hydrogenation catalysts for alkenes, imines, and enamines (up to 99% ee in all cases), whilst in some cases TON of up to 1000 have been achieved. 

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