105928-96-9Relevant academic research and scientific papers
ASYMMETRIC OXIDATION OF OLEFINS TO VICINAL DIOLS WITH OSMIUM TETROXIDE
Tokles, Maritherese,Snyder, John K.
, p. 3951 - 3954 (1986)
High levels of asymmetry can be achieved in the osmium tetroxide cis-hydroxylation of olefins by employing (-)-(R,R)-N,N,N',N'-tetramethylcyclohexane-1,2-trans-diamine as a chiral ligand for the osmium.
Manipulating the Expression Rate and Enantioselectivity of an Epoxide Hydrolase by Using Directed Evolution
Reetz, Manfred T.,Zheng, Huabao
, p. 1529 - 1535 (2011)
We describe here a strategy to improve the expression efficiency and enantioselectivity of Aspergillus niger epoxide hydrolase (ANEH) by directed evolution. Based on a blue-colony screening system using the LacZα (β-galactosidase α peptide) complementation solubility reporter, several ANEH variants out of 15000 transformants from a random-mutagenesis library were identified that show improved recombinant expression in E. coli. Among them, Pro221Ser was subsequently used as a template for iterative saturation mutagenesis (ISM) at sites around the ANEH binding pocket. Following four rounds of ISM, a highly enantioselective mutant was identified that catalyzes the hydrolytic kinetic resolution of racemic glycidyl phenyl ether with a selectivity factor of E=160 in favor of the (S)-diol compared to WT ANEH characterized by E=4.6. Expression of this mutant is 50 times higher than that of WT ANEH. It also serves as an excellent stereoselective catalyst in the hydrolytic kinetic resolution and desymmetrization of several other structurally diverse epoxides. Copyright
Sodium chlorite as an efficient oxidant and hydroxy ion pump in osmium-catalyzed asymmetric dihydroxylation
Junttila, Mikko H.,Hormi, Osmo E. O.
, p. 4816 - 4820 (2004)
Sodium chlorite is an efficient stoichiometric oxidant in Sharpless asymmetric dihydroxylation. One sodium chlorite provides the reaction with the stoichiometric number of electrons and hydroxide ions needed to dihydroxylate two olefins without the consumption of any additional base. 100% conversion in sodium chlorite asymmetric dihydroxylation of styrene was achieved twice as fast as in the established Sharpless K3[Fe(CN)6] dihydroxylation. Even internal olefins were dihydroxylated fast with sodium chlorite without hydrolysis aids. Eight olefins were dihydroxylated to corresponding vicinal diols with yields and ees as good as those reported in the literature for other similar processes.
Clean osmium-catalyzed asymmetric dihydroxylation of olefins in ionic liquids and supercritical CO2 product recovery
Branco, Luis C.,Serbanovic, Ana,Da Ponte, Manuel Nunes,Afonso, Carlos A. M.
, p. 107 - 109 (2005)
The combination of ionic liquids (ILs) as solvents in the asymmetric Sharpless dihydroxylation (AD) with the use of ScCO2 in the separation process allows a very simple, efficient, clean and robust system for the reuse of the AD catalytic system, which also does not need the use of organic solvents either for the reaction or for the separation of products and allows the isolation of the diol, in high yield and enantiomeric excess and basically without contamination with osmium.
Catalytic asymmetric dihydroxylation of olefins using a recoverable and reusable OsO42- in ionic liquid [bmim][PF6]
Branco, Luis C.,Afonso, Carlos A. M.
, p. 3036 - 3037 (2002)
The use of the solvent systems water/ionic liquid or water/ionic liquid/tert-butanol provides a recoverable, reusable, robust and simple system for the asymmetric dihydroxylation of olefins, based on the immobilization of the osmium-ligand catalyst in the ionic liquid phase.
Osmium-Catalyzed Dihydroxylation of Olefins Using Dioxygen or Air as the Terminal Oxidant
Doebler, Christian,Mehltretter, Gerald M.,Sundermeier, Uta,Beller, Matthias
, p. 10289 - 10289 (2000)
The osmium-catalyzed dihydroxylation of various olefins using molecular oxygen or air as the stoichiometric oxidant is reported. Aromatic olefins yield the corresponding diols in good to excellent chemoselectivities under optimized pH conditions (pH = 10.4-12.0). Air can be used under moderate pressures (3-9 bar) instead of dioxygen as the reoxidant. By increasing the oxygen content of the solution, it is possible to achieve highly efficient conversion at low catalyst amount (catalyst/substrate = 1:4000). Tri- and tetrasubstituted olefins are oxidized at pH > 11 to give the corresponding 1,2-diols in good to very good yields without requiring the addition of sulfonamides or other hydrolysis agents. Studies of the dihydroxylation of functionalized olefins demonstrate that the reaction conditions tolerate a variety of functional groups. In the presence of dihydroquinine or dihydroquinidine derivatives (Sharpless ligands), asymmetric dihydroxylations occur with lower enantioselectivities than tose of the classical K3[Fe(CN)6] reoxidation system.
Chemoenzymic resolution and deracemisation of (±)-1-methyl-1,2- epoxycyclohexane: The synthesis of (1-S, 2-S)-1-methylcyclohexane-1,2-diol
Archer, Ian V. J.,Leak, David J.,Widdowson, David A.
, p. 8819 - 8822 (1996)
Corynebacterium C12 epoxide hydrolase transforms (±)-1-methyl-1,2-epoxy-cyclohexane 1 to the (1-S, 2-S)-1-methylcyclohexane-1,2-diol 2 leaving the (1-S, 2-R)-epoxide 3 unchanged. The diol 2 is converted to the (1-R, 2-S)-epoxide 4 by sulfonation-ring closure. A one pot combination of Corynebacterium C12 epoxide hydrolase and acid catalysed ring opening converts (±)-1-methyl-1,2-epoxycyclohexane 1 to (1-S, 2-S)-1-methylcyclohexane-1,2-diol 2.
Sharpless asymmetric dihydroxylation of olefins in water-surfactant media with recycling of the catalytic system by membrane nanofiltration
Branco, Luis C.,Ferreira, Frederico Castelo,Santos, Jose L.,Crespo, Joao G.,Afonso, Carlos A. M.
, p. 2086 - 2098 (2008)
This paper presents a new and more sustainable alternative approach for the Sharpless catalytic asymmetric dihydroxylation (AD) of olefins using a water/surfactant systemas reaction media. The AD reaction was performed using several cationic and anionic surfactants allowing yields and enantiomeric excesses higher or comparable with the conventional systems (using organic mixtures). The use of this water/surfactant medium offers the additional advantage of performing the reactions without the need of a slow addition of olefins. Asymmetric dihydroxylation of 1-hexene in a 1.5 mM sodium cholate aqueous solution, using N-methylmorpholine N-oxide (NMO) as co-oxidant was selected as model systemto evaluate the feasibility of recycling the Sharpless catalytic systemby nanofiltration. The reaction media was processed by nanofiltration, the product was isolated in the permeate, whereas the catalytic systemand surfactant were retained by the membrane and recycled through six successive reactions, improving the catalyst turn-over number. The experimental results were compared with the ones calculated on the basis of mass balances, membrane rejections to product and reaction yields.
Acid-catalyzed enzymatic hydrolysis of 1-methylcyclohexene oxide
Van Der Werf, Mariet J.,De Bont, Jan A. M.,Swarts, Henk J.
, p. 4225 - 4230 (1999)
Limonene-1,2-epoxide hydrolase from Rhodococcus erythropolis DCL14, an enzyme involved in the limonene metabolism of this microorganism, catalyzes the enantioselective hydrolysis of 1-methylcyclohexene oxide. (1R,2S)-1- Methylcyclohexene oxide was the preferred substrate and it was mainly hydrolyzed to (1S,2S)-1-methylcyclohexane-1,2-diol, while (1S,2R)-1- methylcyclohexene oxide was converted more slowly and mainly yielded (1R,2R)- 1-methylcyclohexane-1,2-diol. The reaction proceeded with a high regioselectivity (C1:C2, 85:15). H218O-labelling experiments confirmed that the nucleophile was mainly incorporated at the most substituted carbon atom, suggesting that limonene-1,2-epoxide hydrolase uses an acid-catalyzed enzyme mechanism.
Efficient photocatalytic oxidation of cycloalkenes by dihydroxo(tetraphenylporphyrinato)-antimony supported on silica gel under visible light irradiation
Shiragami, Tsutomu,Makise, Ryu-Ichi,Inokuchi, Yousuke,Matsumoto, Jin,Inoue, Haruo,Yasuda, Masahide
, p. 736 - 737 (2004)
In order to develop a photocatalyst operating under visible light irradiation, silica gel-supported dihydroxo(tetraphenylporphyrinato)antimony (V) complex, [SbTPP(OH)2]+/SiO2, was prepared. The photocatalytic oxidation of cycloalkenes with oxygen molecule was performed on [SbTPP(OH)2]+/SiO2 particles under irradiation of fluorescent light. The photocatalytic oxidation of cycloalkenes gave the corresponding cis-1,2-epoxycycloalkane, 2-cycloalkene-1-ol, and trans-1,2-cycloalkanediol.
