56718-04-8Relevant articles and documents
Combination of Metal-Catalyzed Cycloisomerizations and Biocatalysis in Aqueous Media: Asymmetric Construction of Chiral Alcohols, Lactones, and γ-Hydroxy-Carbonyl Compounds
Rodríguez-álvarez, María J.,Ríos-Lombardía, Nicolás,Schumacher, S?ren,Pérez-Iglesias, David,Morís, Francisco,Cadierno, Victorio,García-álvarez, Joaquín,González-Sabín, Javier
, p. 7753 - 7759 (2017/11/10)
The combination of the metal-catalyzed cycloisomerization of alkynes containing a tethered nucleophile as substituent in aqueous media (followed by the spontaneous hydrolysis, hydroalkoxylation, or aminolysis of the transiently formed five-membered heterocycles) with the subsequent enantioselective ketone bioreduction (mediated by KREDs) has been achieved. The overall transformations, which formally involve a three-step one-pot reaction, provide a variety of enantiopure valuable molecules (e.g., 1,4-diols, lactones, and γ-hydroxy-carbonyl compounds (carboxylic acids, esters, and amides)) with high conversions and enantioselectivities and under mild reaction conditions, disclosing the concept of integrated metal-catalyzed cycloisomerizations of alkynes and enzymatic catalysis in water.
Asymmetric synthesis of 2-substituted butane-1,4-diols by hydrogenation of homochiral fumaramide derivatives
Jawaid, Samaila,Farrugia, Louis J.,Robins, David J.
, p. 3979 - 3988 (2007/10/03)
Diastereoselective hydrogenation of homochiral fumaramides 1 derived from (2R)-Oppolzer's sultam was observed by analysis of the 1H NMR spectra of the succinamide mixtures with de's of 77-88%. Reduction of these succinamides using LiAlH4 gave the corresponding (2S)-butane-1,4- diols and established that addition of hydrogen takes place selectively on the re-face of fumaramides 1. The stereoselectivity was confirmed by estimating the ee's from the 19F NMR spectra of the Mosher's diesters of the diols. This methodology was applied to the synthesis of selected pyrrolidine natural products in homochiral form.
Substrate structure and incubation-parameter-dependent selectivities in chiral discrimination of galactopyranosides by β-galactosidase hydrolysis
Werschkun, Barbara,Koenig, Wilfried A.,Kren, Vladimir,Thiem, Joachim
, p. 2459 - 2466 (2007/10/02)
Mono-β-galactopyranosides of (+/-)-propane-1,2-diol, (+/-)-butane-1,3-diol, (+/-)-pentane-1,4-diol, (+/-)-butan-2-ol, (+/-)-pentan-2-ol and (+/-)-1,2-O-isopropylideneglycerol were synthesized by the Koenigs-Knorr reaction using hydroxycarbonyl compounds as precursors for the diolic substrates.Hydrolysis of 3-hydroxybutyl β-D-galactopyranoside 18 by β-galactosidases from Eschrichia coli, Aspergillus oryzae, Kluyveromyces lactis and Bacillus circulans, respectively, resulted in each case in an enantiomeric enrichment of the released diol.This was most significant with the E. coli enzyme and and increased with higher reaction temperature and shorter incubation periods.Under standartized conditions, cleavage of all synthesized galactopyranosides by this enzyme showed the highest stereoselectivity for butane-1,3-diol, butan-2-ol and isopropylideneglycerol with enantiomeric excesses in the range 60-75percent.For compounds with structural similarity to the natural substrate lactose, enhanced stereodiscriminations were expected.However, this could not be confirmed and instead a specific hydrophobic interaction is suggested to play a crucial role.