160865-93-0Relevant academic research and scientific papers
Chiral linear polymers bonded alternatively with salen and 1,4-dialkoxybenzene: Synthesis and application for Ti-catalyzed asymmetric TMSCN addition to aldehydes
Sakthivel, Sekarpandi,Punniyamurthy, Tharmalingam
experimental part, p. 2834 - 2840 (2011/03/19)
The synthesis of chiral linear polymers 1a-b having salen and 1,4-dioctyloxybenzene as alternate segments has been accomplished. The GPC analysis showed the molecular weights corresponding to ca. 15 (Mw = 10,999, Mn = 9165 and PDI = 1.20) repeating units for 1a and ca. 8 (Mw = 8547, Mn = 7883 and PDI = 1.08) repeating units for 1b. Polymers 1a-b have been studied with Ti(OiPr)4 as a recyclable catalyst for the asymmetric addition of TMSCN to aldehydes while the selectivity of the polymer catalyst is identical to that of the monomer. The reactions are efficient affording the cyanohydrins with up to 88% ee. The selectivity of the polymer based catalyst 9a is found to be the same to that of the monomer 10a. The reaction provides the advantages of simplified product isolation and easy recovery and recyclability of polymer catalyst 9a without any loss of activity or selectivity.
The substrate spectrum of mandelate racemase: Minimum structural requirements for substrates and substrate model
Felfer, Ulfried,Goriup, Marian,Koegl, Marion F.,Wagner, Ulrike,Larissegger-Schnell, Barbara,Faber, Kurt,Kroutil, Wolfgang
, p. 951 - 961 (2007/10/03)
Mandelate racemase (EC 5.1.2.2) is one of the few biochemically well-characterized racemases. The remarkable stability of this cofactor-independent enzyme and its broad substrate tolerance make it an ideal candidate for the racemization of non-natural α-hydroxycarboxylic acids under physiological reaction conditions to be applied in deracemization protocols in connection with a kinetic resolution step. This review summarizes all aspects of mandelate racemase relevant for the application of this enzyme in preparative-scale biotransformations with special emphasis on its substrate tolerance. Collection and evaluation of substrate structure-activity data led to a set of general guidelines, which were used as basis for the construction of a general substrate model, which allows a quick estimation of the expected activity for a given substrate.
Highly enantioselective cyanosilylation of aldehydes catalyzed by novel β-amino alcohol-titanium complexes
Li, Yan,He, Bin,Qin, Bo,Feng, Xiaoming,Zhang, Guolin
, p. 7910 - 7913 (2007/10/03)
The β-amino alcohol 1b-Ti(Oi-Pr)4 complex has been shown to catalyze the enantioselective cyanosilylation of aldehydes efficiently. In the presence of 5 mol % of 1b-Ti(Oi-Pr)4 complex catalyst, the aromatic, conjugated, heteroaromatic, and aliphatic aldehydes were converted to their corresponding trimethylsilyl ethers of cyanohydrins in 90-99% yields with up to 94% ee under mild conditions.
Ueber die erste rekombinante Hydroxynitril-Lyase und ihre Anwendung in der Synthese von (S)-Cyanhydrinen
Foerster, Siegfried,Roos, Juergen,Effenberger, Franz,Wajant, Harald,Sprauer, Achim
, p. 493 - 494 (2007/10/03)
Keywords: Asymmetrische Synthesen; (S)-Cyanhydrine; Enzymkatalyse; Lyasen
Synthesis of α,β-unsaturated (S)-cyanohydrins using the oxynitrilase from Hevea brasiliensis
Klempier,Pichler,Griengl
, p. 845 - 848 (2007/10/02)
α,β-unsaturated (S)-cyanohydrins derived from 2-propenal, 2-butenal, (E) and (Z)-2-hexenal and 2-hexynal are obtained in high enantiomeric purity (80-95%, e.e.) by using an oxynitrilase isolated from the leaves of Hevea brasiliensis.
Asymmetric Carbon-Carbon Bond Forming Reactions Catalyzed by Chiral Schiff Base-Titanium Alkoxide Complexes
Hayashi, Masahiko,Inoue, Tetsuya,Miyamoto, Yasunori,Oguni, Nobuki
, p. 4385 - 4398 (2007/10/02)
The enantioselective addition of trimethylsilyl cyanide to a variety of aldehydes proceeded by the aid of a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases and gave the corresponding cyanohydrins in high optical yield (up to 96percent e.e.).A remarkable rate enhancement was brought about by the addition of the Schiff base to the titanium alkoxide mediated silylcyanation of aldehydes.This catalyst system also promoted the highly enantioselective reaction of diketene with aldehydes, which led to the formation of optically active 5-hydroxy-3-oxoesters.
Enantioselective Trimethylsilylcyanation of Some Aldehydes Catalyzed by Chiral Schiff Base-Titanium Alkoxide Complexes
Hayashi, Masahiko,Miyamoto, Yasunori,Inoue, Tetsuya,Oguni, Nobuki
, p. 1515 - 1522 (2007/10/02)
A variety of aldehydes (aromatic, heteroaromatic, α,β-unsaturated, and nonconjugate aliphatic aldehydes) has been trimethylsilylcyanated in highly enantiomeric excess (ee) with a catalyst prepared in situ from titanium tetraisopropoxide and chiral Schiff bases.A remarkable rate enhancement was brought about by the addition of the Schiff base into the titanium alkoxide mediated silylcyanation of aldehydes.The chemical structure of chiral Schiff base-titanium alkoxide complexes is discussed based on their 13C NMR spectra, field desorption (FD) mass spectra, and molecular weights.
