10172-89-1Relevant articles and documents
Cross-linked crystals of subtilisin: Versatile catalyst for organic synthesis
Wang, Yi-Fong,Yakovlevsky, Kirill,Zhang, Bailing,Margolin, Alexey L.
, p. 3488 - 3495 (1997)
Cross-linked enzyme crystals (CLECs) of subtilisin exhibit excellent activity in aqueous and various organic solvents. This catalyst is more stable than the native enzyme in both aqueous and mixed aqueous/organic solutions. Subtilisin-CLEC was shown to be a versatile catalyst. It was used for the syntheses of peptides and peptidomimetics, mild hydrolysis of amino acid and peptide amides, enantio- and regioselective reactions, and transesterifications.
Modular solid-phase synthesis, catalytic application and efficient recycling of supported phosphine-phosphite ligand libraries
Heutz, Frank J. L.,Kamer, Paul C. J.
, p. 2116 - 2123 (2016)
In spite of decades of research in the field of homogeneous asymmetric catalysis the discovery of new high performance catalysts still relies heavily on trial-and-error. There is still a lack of efficient combinatorial methods which enable the synthesis and screening of vast ligand libraries, especially for bidentate phosphorus ligands. Here we present a highly modular solid-phase synthetic approach which provides facile access to libraries of phosphine-phosphite ligands in quantitative yield requiring only minimal work-up. The obtained library of supported phosphine-phosphites was successfully applied in rhodium catalyzed asymmetric hydrogenation obtaining high enantioselectivities up to 98%. Also, these polymer supported ligands could be successfully recycled under batch conditions exhibiting only a small decline of activity and no loss of selectivity.
Enantioselective hydrolytic reactions of rice bran lipase (RBL): A first report
Fadnavis,Jadhav, Vasudev
, p. 2361 - 2366 (1997)
Enantioselectivity has been observed in the hydrolysis of racemic N-acetyl amino acid esters with rice bran lipase (RBL). The enzyme shows selectivity towards the (S)-enantiomer. Products with high enantiomeric excess (e.e. >99%) are obtained depending upon the hydrophobicity of the amino acid as well as that of the leaving group.
ASYMMETRIC HYDROGENATION OF α-ACYLAMINOACRYLIC ACIDS AND ESTERS WITH AXIALLY DISSYMMETRIC BISAMINOPHOSPHINE-RHODIUM COMPLEXES
Miyano, Sotaro,Nawa, Masayoshi,Hashimoto, Harukichi
, p. 729 - 730 (1980)
From easily resolved 2,2'-diamino-1,1'-binaphthyl were prepared axially dissymmetric bisphosphine ligands, (R)- and (S)-2,2'-bis(diphenylphosphinamino)-1,1'-binaphthyl; the rhodium-catalyzed asymmetric hydrogenation of α-acylaminoacrylic acids and esters gave the corresponding amino acids of up to 95percent optical purity.
Modified silica-heterogenised catalysts for use in aqueous enantioselective hydrogenations
Jamis, Jim,Anderson, John R.,Dickson, Ron S.,Campi, Eva M.,Jackson, W. Roy
, p. 37 - 43 (2001)
Modified mesoporous silicas have been prepared, homogeneous organometallic catalysts incorporated and the resulting heterogeneous systems used as catalysts in aqueous enantioselective hydrogenation reactions. A series of catalysts in which the organometallic species was incorporated during gel synthesis generally gave good conversions but low ee values which were usually less than 25%. Preformed silicas with a narrow range of pore size (26 and 37 ?) and an amorphous silica (average pore size 68 ?) were modified by external surface deactivation and/or derivatization of the internal surface for potential tethering of the catalytic species. In general, excellent conversions (80-100%) but modest enantioselectivities (40-50%) were obtained when using 37 and 68 ? silicas, similar to those values obtained using unmodified silicas. Only low conversions were obtained using the modified 26 ? silicas. Pore volume measurements suggest that this is due to very restricted access to the pores when the tether is present. The results indicate that for aqueous hydrogenation the van der Waals interactions of the catalyst with the porous matrix are sufficiently strong to retain the catalyst, thus allowing for its reuse. No major advantage then appears to be gained by the use of potential internal tethers.
Asymmetrische Katalyse III. Synthese, spektroskopische Untersuchungen und katalytische Wirkung eines neuen chiralen Phosphanliganden
Tillack, Annegret,Michalik, Manfred,Fenske, Dieter,Goesmann, Helmut
, p. 95 - 100 (1993)
The reduction of 3,4-bis(dimenthylphosphino)maleic anhydride (2) with LiAlH4 yields a new optically-active P-ligand, the chiral γ-lactone 3.The structure of 3 was determined by 1H, 13C and 31P-NMR spectroscopy, and X-ray crystal structure analysis.This ligand is used as co-catalyst with BF4 in the catalytic hydrogenation of α-acetamidocinnamic acid and methyl α-acetamidocinnamate.Optical yields of up to 75percent were obtained with the ester.
Chirale Bisphosphane VIII. Die enantioselektive Hydrierung von α-Acetamidozimtsaeure durch kationische Rhodium(I)-Komplexe mit optisch reinen (1S,2S)-Cyclopentan-1,2-diyl-bis(phosphonigsaeurediester)- und (1S,2S)-Cyclopentan-1,2-diyl-bis(phosphonigsaeurediamid)-Liganden1
Dahlenburg, Lutz,Eckert, Christine
, p. 227 - 232 (1998)
Treatment of [(1,5-COD)2Rh]O3SCF3 with optically active P2 ligands of the type (1S,2S)-C5H8(PR2)2 [PR2=P(OMe)2 (3), P(OPh)2 (4), P[OCH(Me)Et-(S)]2 (5), P[2-OC10H6C10H6O-2′-(R)] (6), P(NC4H8O-cyclo)2 (7)] gave cationic rhodium complexes bearing these new ligands, [(1,5-COD)Rh{(PR2)2C5H8-(1S,2S)}]O3SCF3 (Rh-3-7). Use of these as catalysts in the homogeneous enantioselective hydrogenation of α-acetamidocinnamic acid to N-acetylphenylalanine provided optical yields of 75-78% ee for the complexes [(1,5-COD)Rh{[P(OPh)2]2C5H8-(1S,2S)} ]O3SCF3 (Rh-4) and [(1,5-COD)Rh{(P[OCH(Me)Et-(S)]2)2C5H8-(1S,2S)}]O3SCF3 (Rh-5), respectively.
A novel tea-bag methodology for enzymatic resolutions of α-amino acid derivatives in reverse micellar media
Bhalerao,Rao,Fadnavis
, p. 2109 - 2118 (1994)
A novel tea bag methodology for resolution of methyl esters of N-acetyl- α-amino acids in reverse micellar medium of bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) in isooctane-chloroform using immobilized enzymes or microbial cells is presented. The methodology effectively solves the problems of substrate solubility, product separation and surfactant recycling and provides products in high yields (80 to 90%) and excellent optical purities (% ee 97 to >99%).
Facile preparation of an enzyme-immobilized microreactor using a cross-linking enzyme membrane on a microchannel surface
Honda, Takeshi,Miyazaki, Masaya,Nakamura, Hiroyuki,Maeda, Hideaki
, p. 2163 - 2171 (2006)
The enzyme microreactor has considerable potential for use in biotechnological syntheses and analytical studies. Simplifying the procedure of enzyme immobilization in a microreactor is attractive, and it is achievable by utilizing enzyme immobilization techniques and taking advantage of the characteristics of microfluidics. We previously developed a facile and inexpensive preparation method for an enzyme-immobilized microreactor. The immobilization of enzymes can be achieved by the formation of an enzyme-polymeric membrane on the inner wall of the microchannel through cross-linking polymerization in a laminar flow. However, this method is unsuitable for use in conjunction with electronegative enzymes. Therefore, a novel preparation method using poly-L-lysine [poly(Lys)] as a booster and an adjunct for the effective polymerization of electro-negative enzymes was developed in this study. Using aminoacylase as a model for an electronegative enzyme, the reaction conditions for the enzyme-cross-linked aggregation were optimized. On the basis of the determined conditions, an acylase-immobilized tubing microreactor was successfully prepared by cross-linking polymerization in a concentric laminar flow. The resulting microreactor showed a higher stability against heat and organic solvents compared to those of the free enzyme. The developed method using poly(Lys) was applicable to various enzymes with low isoelectric points, suggesting that this microreactor preparation utilizing a cross-linked enzyme in a laminar flow could be expanded to microreactors in which a broad range of functional proteins are employed.
P-chirogenic diphosphazanes with axially chiral substituents and their use in rh-catalyzed asymmetric hydrogenation
Moritz, Jan-Ole,Chakrabortty, Soumyadeep,Bernd H. Mu.ller,Spannenberg, Anke,Kamer, Paul C. J.
, p. 14537 - 14544 (2020)
A convenient synthesis of enantiopure P-chirogenic diphosphazanes incorporating bulky bisphenol and 1,1′-bi-2-naphtholderived substituents via the functionalization of a readily accessible enantiopure lithium phosphinoamide with chlorophosphoridites was developed. Since the product requires no subsequent deprotection, the protocol provides an easy, convenient synthesis of P-chirogenic ligands on the gram scale. The ligands were applied in the Rh-catalyzed asymmetric hydrogenation of benchmark substrates furnishing enantiomeric excess values up to 96%.
