Izumi system

Fig. 3.15 Best results for the enantioselective hydrogenation of / -functionalized ketones and non-functionalized ketones using the Izumi system.

Ohshiro, T. Kanbayashi, Y. Hine, Y., and Izumi, Y., Involvement of Flavin Coenzyme in Dibenzothiophene Degrading Enzyme-System from Rhodococcus-Erythropolis D-l. Bioscience Biotechnology and Biochemistry, 1995. 59(7) pp. 1349-1351. 

One of the important conclusions of the early attempts was that it is fruitful to place the functionality near an optically active support. Already in 1958, Isoda and coworkers reported for the first time the enantioselective hydrogenation with a Raney nickel catalyst modified with optically pure amino acids. Optical yields reported at that time were from low (2.5%) to moderate (36%) values (for references see [12]). Subsequently, in 1963, Izumi and coworkers [100] initiated an extended study of the modified Raney nickel system with TA. As a result of their initial researches, this system was the first heterogeneous chiral catalyst to give high enantioselectivities in the hydrogenation of / -ketoesters (95%) [101,102],... 

The Ni-tartaric acid system was discovered by Izumi et al. [40] and gives, under optimized conditions, e.e.s >90% in the hydrogenation of -keto esters. Even with simple ketones good results are obtained, e.g., 2-octanone 80% e.e. [41]. As yet the mechanism of the enantioselectivity is not well understood. 

Since then, a number of studies of model systems have confirmed that dialkenes, cyclic alkenes, and aromatics form substituted monocarboxylic acids, dicar-boxylic acids, and organic nitrates in the condensed phase (e.g., see O Brien et al., 1975a Grosjean and Friedlander, 1979 Dumdei and O Brien, 1984 Izumi and Fukuyama, 1990 and Forstner et al., 1997a, 1997b). For example, Table 9.21 shows the products identified in particles formed in the 1-octene- and 1-decene-NO,-ambient air systems. In both bases, only 40% of the total particle mass could be identified, and the yields shown in Table 9.21 are those relative to the total identified compounds. That is, the absolute product yields are about factor of 2.5 larger. As expected from the known oxidation mechanisms (see Chapter 6.E), heptanal and heptanoic acid are the major condensed-phase oxidation products of 1-octene and nonanal and nonanoic acid from 1-decene (see Problem 4). The mechanism of formation of the fura-nones, which are formed in relatively high yields, is not... 

There are examples requiring extension to double terms, a possibility apparently not discussed by Izumi and Tai. although their system can cope with the problems that arise. The following example was reported by Jiiger2 ... 

As is apparent from a recent review there are many examples of this lype of reaction known see R. S. Ward, Client. Soe. Rev. 19, 1 (1990). Concerning terminology, the title of this article is interesting "Non-Enzymatic Asymmetric Transformations Involving Symmetrical Bifunctional Compounds". Using the Izumi-Tai system the title could have been much shorter and precise Non-Enzy-matic Enantiotopos-Differentiating Reactions. 

In retrospect, it was a consistent and logical step for Seebach and Prelog to propose, in 1982 2 a reactant-based descriptor system (SP system) corresponding to the Izumi -Tai classification. The SP system makes use of the familiar Re Si system already discussed (see Section 1.1.2.2.). Again, relative configurational relationships must be incorporated, something which the SP system does by straightforward combination of descriptors into Ikjul pairs (relative topicities) (see Section 1.1.2.2. and 1.1.4.). 

Thus, combining the Izumi-Tai classification of stereoselectivity and stereodifferentiation with the CIP and the SP systems has led to a coherent, logical and universal system that allows unambiguous assessment of configurational relationships of stereoselective reactions. 

The descriptors of relative topicity are used in Iwo different ways as they may be derived from inter- or intramolecular combinations. It is prescribed that the descriptor of the former precedes that of the latter combinations nevertheless, extended strings of descriptors can be quite cumbersome. In order to help readability, brackets are added that contain the mfromolecular relative topicities, in accordance with the extension of the Izumi Tai terms described in Section 1.1.3.1. Such brackets are particularly helpful when examples of double stereodifferentiation are to be described (see Section 1.2.2.5.). The SP system is also a powerful tool here its application to the examples previously displayed in Section 1.2.2.5. is straightforward ... 

During the early phase of an investigation there is usually very little information available and therefore, the goal is to find a "lead" which then can be developed and improved further to give e.g. a synthetically useful system. The approach most often used is what one could call "screening with a concept experiments are set up in order to test an intuitive idea or a more or less well defined hypothesis. A good illustration for this approach is described by Izumi [4] "we expected simply that an optically active product should be produced from the influence of the optically active environment, like baking a waffle. We used silk fibroin as a waffle iron ". 

Various other physical methods have been applied to the study of protein hydration in multicomponent systems, for example, NMR spectroscopy of frozen samples (Izumi et ai, 1980), scanning calorimetry (Fujita et ai, 1982), thermodynamics of denaturation (Velicelebi and Sturte-vant, 1979), and sorption (Stonehouse, 1982). 

O Neill and Stannett (1974) also found, with sodium lautyl sulfiite as the emulsifier, that when a separate monomer (Aiase was present a milky slurry that was 100% filterable was formed even at low conversions. However, in the water-soluble region low solid latices were obtained. The initial rates were much higher than in the absence of emulsifiers as was previously reported by Karpov et al- A plot of tbe initial rates versus tbe monomer concentration is shown in Fig. 5. A first-order dependence on monomer concentration was found. Again, as with Karpov et al., considerable useful data is presented for systems where a separate monomer phase is present. Since these are not truly emulsion polymerizations, further details will not be discussed in this chapter. The molecular weights were essentially independent of the emulsifier concentration and in the same range, about 10 as found by Karpov et id. Izumi et al. (1967 Izumi, 1967) obtained similar results with ammonium persulfate as the initiator. 

Pernambuco, J.R.B., Langley, P.G., Hughes, R.D., Izumi, S., Williams, R. Activation of the fibrinolytic system in patients with fulminant liver failure. Hepatology 1993 18 1350-1356... 

Izumi, J. and Mukaiyama, T. 1996. The catalytic Friedel-Crafts acylation reaction of aromatic compounds with carboxylic anhydrides using combined catalysts system of titanium(IV) chloride tris(trifluoromethanesulfonate) and trifluoromethanesulfonic acid. Chem. Lett. 739-740. 

Tsuboi, A., Izumi, T., Hirata, M., Xia, J.L., Dubin, P.L., Kokufuta, E. Complexation of proteins with a strong polyanion in an aqueous salt free system. Langmuir 1996,12 (26), 6295-6303. 

IZU Izumi, Y. and Miyake, Y., Study of linear poly(p-chlorostyrene)-diluent systems. I. 

IZU Izumi, Y., Dondos, A., Picot, C., and Benoit, H., Etude des solutions de polymeres dans un melange de solvants au voisinage de leur point critique de demixtion, 1. Systeme methanol/cyclohexane/polyvinyl-2-pyridine, A/aArowo/. Chem., 180, 2483, 1979. 

Ninokata, H.. Izumi, A., Decay Heat Removal System of the Monju Reactor Plant and Studies Related to the Passive Actuation and Performances, Proc, of the Intemat. Fast Reactor Safety Meeting, Snow-bird, USA, 1990. 

Kobayashi, M., Yoshioka, T., Kozasa, T., Tashiro, K., Suzuki, J.-I., Funahashi, S., Izumi, Y. Structure of physical gels formed in syndiotactic polystyrene/solvent systems studied by smaU-angle neutron scattering. Macromolecules, 27,1349-1354 (1994). 

K. Momma and F. Izumi, /. Appl. Crystallogr., 41, 653-658 (2008). VESTA A Three-Dimensional Visualization System for Electronic and Structural Analysis. 

Funk CD, Gunne H, Steiner H, Izumi T, Samuelsson B. Native and mutant 5-lipoxygenase expression in a baculovirus insect cell system. Proc Natl Acad Sci USA 1989 86 2592-2596. 

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