Asymmetric hydrogenations acetoacetate

To our knowledge, there is to date only one report concerning asymmetric hydrogenation using a SILP catalyst [117]. Methyl acetoacetate was hydrogenated using Ru-BINAP dissolved in [BMIM][PF6] and immobilized on the poly(diallyl-dimethy-lammonium chloride) support (Fig. 41.14). 

Ligand (349), water-soluble (350), and their (R)-enantiomers have been synthesized, and their Ru complexes used as catalysts (see also Section 5.5.3.2.5) for the asymmetric hydrogenation of methyl acetoacetate and (Z)-acetamidocinnamic acid. " The complex [Ru (5)-351 (OAc)2] and... 

The 5-isomer is available by yeast reduction of acetoacetate.1-4 -50 Both isomers are available by asymmetric hydrogenation of the (3-keto ester (Chapters 12 and 13).51... 

Comparisons in the asymmetric hydrogenation of methyl acetoacetate (111) with ruthenium catalysts that contain C2-Tunephos (110b) and 116 indicated an improvement in enantiomeric excess when the ether linkage contained additional chirality.134140... 

Asymmetric hydrogenation. Raney nickel that has been soaked at 100° in an aqueous solution of tartaric acid and sodium bromide can effect asymmetric hydrogenation of methyl acetoacetate to methyl 3-hydroxybutyrate and of acetylacetone to 2,4-pentanediol/ In both cases optical yields near 90% can be achieved. 

Although palladium on polypeptide sterns mentioned above are heterogei mis, homogeneous system may be realized by the complexation of ruthenium(III) ion to poly(S-glutamic acid), which was fwnd effective as catafyst for the asymmetric hydrogenation of methyl acetoacetate (Hirai, Aikawa, Fumta (7)). 

Fig. 1. Asymmetric hydrogenation of methyl acetoacetate catalyzed by ruthenium(III) complex with (7) ...

In connection with these studies, the asymmetric hydrogenation catalyzed by Raney nickel modified with dipeptide should be mentioned. In the hydrogenation of methyl acetoacetate [Eq. (5)], Izumi and his co-workers (70) found that the... 

Ozaki, H., Tai, A., and Izumi, Y. (1974) Enantioface-differentiating (asymmetric) hydrogenation of methyl acetoacetate with modified Raney nickel, XXVIII, Chem. Lett. 935 - 938. 

Neupokoev, V.I., Petrov, Yu.L, and Klabunovskii, E.L (1976) Asymmetric hydrogenation of acetoacetic ester on skeletal Co and Cu catalysts modified with D-(+)-tartaric acid, Izv. AN SSSR Ser. khim. 113-117, Chem. Abstr. 84, 150160a. 

Klabunovskii, E.I., Neupokoev, V.L, and Petrov, Yu.I. (1970) Asymmetric hydrogenation of acetoacetic ester on modified skeletal copper catalyst, Izv. AN. SSSR Ser. khim. 2839-2840, Chem. Abstr. 1971, 74, 99415b. 

Orito, Y., Niwa, S., and Imai, S. (1976) Asymmetric hydrogenation of methyl acetoacetate using Nickel-Palladium-Kieselguhr catalysts modified with tartaric acid, Yuki Gosei Kagaku Kiokaishi, J. Synth. Org. Chem. Jpn.) 34, 672 - 674. 

Neupokoev, V.I., Klabunovskii, E.I., Petrov, Yu.l. (1973) Asymmetric hydrogenation of ethyl acetoacetate on dissymmetric cobalt, Kinetika i Ka-taliz (Kinetics and Catalysis) 14, 447-451, Chem. Abstr. 79, 18008z (1973). 

Kambe, S., Kawai, T., and Kawai, S. (1986) Photocatal5dical asymmetric hydrogenation of methyl acetoacetate with CdS modified Raney Ni, J. Chem. Soc. Jpn, 1270-1274... 

P. (2011) Challenging the scope of continuous, gas-phase reactions with supported ionic liquid phase (SILP) catalysts-Asymmetric hydrogenation of methyl acetoacetate. Appl. Catal, A Gen., 399, 35-41. 

I.POXIDATION, ASYMMETRIC (--)-Benzylquininium chloride. f-Butyl hydroperoxide-Vanadyl acetoacetate. Hydrogen peroxide-1,1,3,3-Tetrachloro-aceione. (SM2-Hydroxy-N,N-diinethyl-propanamidc-OtO )oxodiperoxymolyb-denum(VI). 

New work on the asymmetric hetero DA reaction as a route to 2,3-dihydropyran-4-ones includes the use of axially chiral biaryl-based diols <05JA1336> and chiral Bronsted acids <05TL6355> which work through hydrogen bonding. Polymer-bound Danishefsky s diene derived from acetoacetate has been used in the hetero DA reaction with aldehydes. With a chiral BINOL-Ti(IV) complex, good yields of 2-aryl-5-methoxycarbonyl-5,6-dihydropyran-... 

Osawa, T., Mita, S., Iwai, A., Takayasu, 0., Harada, T., and Matsuura, I. (1998) New preparative method of asymmetrically modified nickel catalysts for the enantio-differentiating hydrogenation of methyl acetoacetate. Stud. Surf. Sci. Catal, 118, 313 - 320. 

Osawa, T., Amaya, Y., Harada, T., and Takayasu, O. (2003) Enantio-differentiating hydrogenation of methyl acetoacetate over asymmetrically modified reduced nickel catalysts. The effect of the nickel sources on the enantio-differentiating ability, J. Mol.Catal A Chem. 211,93-96. 

The effect of crystallite size on the optical yield was first observed by Vedenyapin et al. in the hydrogenation of ethyl acetoacetate into ethyl 3-hydrojg butyrate during progressive loading of Ru in Ru-silica catalysts that had been modified with (2R,3R)-tartaric acid. The reaction proved to be structure sensitive. The most effective catalyst proved to be the one with a 4.5 nm crystallite size, while catalysts with crystallite sizes 1.6 and 8.0 nm revealed lower asymmetric abilities. The sizes of the Ru crystallites were increased by increasing reduction times of the catalysts during their preparations. 

---