Imines bases

Regarding the reagent control asymmetric addition to imines, there were three reports with aldo-imines. Based on our best knowledge, no asymmetric addition to ketimine was reported prior to our work (vide infra). 

Park et al.102 demonstrated an interesting intramolecular asymmetric allylation of imine based on a substrate-controlled mode. 

Hagiwara et al.107 reported the chiral Pd(II) complex-catalyzed asymmetric addition of enol silyl ethers to imines, based on the belief that Pd(II) enolate was involved in the reaction. They found that with compound 171a as the catalyst, very low enantioselectivity was obtained in the asymmetric reactions between silyl enol ether and imine compounds (Scheme 3-58). However, in the... 

Brookhart and coworkers [1] have recently developed Ni(II) and Pd(II) bis-imine based catalysts of the type (ArN=C(R)-C(R)=NAr)M-CH3+ (la of Figure 1) that are promising alternatives to both Ziegler-Natta systems and metallocene catalysts for olefin polymerization. Traditionally, such late metal catalysts are found to produce dimers or extremely low molecular weight oligomers due to the favorability of the P-elimination chain termination process [2],... 

Ma and co-workers extended use of chiral guanidine catalysts to the addition of glycine derivatives to acrylates [121], Addition products were achieved in high yield with modest enantioselectivity (Scheme 67). The ferf-butyl glycinate benzophenone imines generally provided better enantiomeric ratios than the ethyl glycinate benzophenone imines. Based on this observation, the authors hypothesized that an imine-catalyst complex determines the stereochemical outcome of the product. 

Keeping in view the biological and synthetic importance of the (3-lactams and the potential of solvent-free microwave chemistry, Kidwai et al. [148] prepared (3-lactams via an ester-imine based synthesis under solvent-free microwave irradiation. The //Y/n.v-4-aminocyclohexanol (128) was condensed with different aromatic aldehyde to give the respective Schiff base. The Schiff-base was then reacted with ethyl a-mercapto/a-cyano acetate, in the presence of basic alumina, to afford the required 3-mercapto/cyano (3-lactams respectively, outlined in Scheme 41. 

Breunig M, Hozsa C, Lungwitz U et al (2008) Mechanistic investigation of poly(ethylene imine)-based siRNA delivery disulfide bonds boost intracellular release of the cargo. J Control Release 130 57-63... 

Figure 12.8 (a) Synthesis of cyclohexane imine-based carbonic anhydrase mimics with a hydro-... 

Another early effort in this direction [51] considered the competition for the bridging proton within the H-bond connecting a formate HCOO anion and an imine base of the sort HN=CH2. In the gas phase, it was found that the neutral pair HCOOH NHCH2 was preferred over an ion pair. However, again as in the aforementioned XH-amine complexes, the ion pair is progressively more favored as the dielectric constant of the medium rises. More specifically, in an in vacuo situation, the neutral pair in which the proton resides on the carboxylate rather than the imine... 

CDC also encompasses dynamic coordination chemistry [35, 38, 40], whereby the coordination of metal ions induces the preferential formation of specific ligand molecules and/or induces reversible changes in them. Such processes may be traced back to early work on coordination reactions of imine-based macrocyclic ligands, when now revisited in the light of constitutional dynamics [52],... 

Herrmann A, Giuseppone N, Lehn J-M (2009) Electric-field triggered controlled release of bioacive volatiles from imine-based liquid crystalline phases. Chem Eur J 15 117-124... 

Fig. 9 (a) Molecular shuttles based on reversible Diels-Alder reaction (al-a6) and sulfur-containing molecular shuttles (a7-al2) (b) methoxy-cycloheptatriene- and methoxy-acridane-based rotaxanes (c) imine-based rotaxanes (see text for details)... 

Cyclopropan 2-tert.-Butyl-l-tert.-butylimino- El 7a, 63 (2-Br— imin/Base)... 

The Kametani group further investigated quinazolone synthesis by cycloaddition of iminoketene with imines based on the concept of retro mass spectral synthesis and applied it to the total syntheses of deoxyvasicinone (24),... 

Table 18 Ethylene polymerization with bis(phenoxy-imine)-based catalysts... 

Molecular mass ligand-substitution effects. Steric and electronic effects can also be used to control the molecular mass of the PEs produced. Bis(phenoxy-imine)-based catalysts can yield polymers ranging from very low to extremely high molecular mass (Mv < 104 orMv > 106).1152 The MAO-activated prototype 135 system yields PEs with very low M v (about 7000-10000 see entries 19-22 in Table 18). As is typical for ct-olefin polymerizations, increasing the... 

Figure 48 Ethylene polymerization activity (g (mmol M) 1 tr1 bar-1) and Mv versus polymerization temperature, TP (°C), for a series of bis(phenoxy-imine)-based catalysts. Top to bottom and left to right, the systems shown correspond to entries 1-3, 7-9, and 38 and 39 in Table 18.

While MAO activation of phenoxy-imine-based complexes results in the syndiospecific polymerization of propylene (see the previous Section), activation of the same complexes with [Ph3C][B(C6F5)4]/Bu 3Al shows completely different behavior. The Ti-based catalyst leads to substantially atactic PP with extremely high molecular mass and rather broad while the Zr- and Hf-based analogs afford moderately isotactic PPs, with moderately high molecular... 

The remarkable effect of [Ph3C][B(C6F5)4]/Bu 3Al activation on the behavior of phenoxy-imine-based catalysts was ascribed to a reaction between Bu 3A1 and the imino functionality of the complexes. As already discussed in Section 4.09.5.3.2, it is commonly accepted that Bu 3A1 reduces the imino group to an amino group, thus converting a phenoxy-imine catalyst into a phenoxy-amine structure.1162... 

Figure 65 Ethylene polymerization performances of Hf- and Zr-based pyrrolide-imine-based catalysts.

Figure 66 Ethylene polymerization with indolide-imine-based catalysts.

Successful examples of chelate assisted activation of aromatic C-F bonds provided the foundation for further exploration of the organometallic chemistry of fluorocarbons. While early examples were limited to perfluorinated aromatic systems, the scope of this process is now fully defined using W(CO)3 and PtMe2 metal fragments [44, 29]. In addition to these amine, imine based ligand systems, several new examples of C-F activation have been achieved using a variety of later transition metals. 

Azides into Amines 20,23,771,772 H2/Pd or H2/Pt 317,318,339,450,773 H2/Pd-(Boc)20 in N-acyloxazolidinoncs to prevent reaction of the amine with the chiral auxiliary 774 Raney nickel 444 SnCh 444,450,458,775,776 Zn 777 Al/Hg 777 sodium borohydride under phase-transfer conditions 778 lithium aluminum hydride 779 H2S 780 triphenylphosphine.325,781,782 Azides into Imines base.783 785 Azides into Enamines NaReC>4.331... 

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