18951-91-2Relevant academic research and scientific papers
Chemoselective screening for the reduction of a chiral functionalised (±)-2-(phenylthio)cyclohexanone by whole cells of Brazilian micro-organisms
Piovan, Leandro,Kagohara, Edna,Ricci, Luis C.,Keppler, Artur F.,Capelari, Marina,Andrade, Leandro H.,Comasseto, Joao V.,Porto, Andre L.M.
, p. 2385 - 2389 (2008)
The use of whole cells of micro-organisms to bring about the biotransformation of an organic compound offers a number of advantages, but problems caused by enzymatic promiscuity may be encountered upon with substrates bearing more than one functional group. A one-pot screening method, in which whole fungal cells were incubated with a mixture of 4-methylcyclohexanone 1 and phenyl methyl sulfide 2, has been employed to determine the chemoselectivity of various biocatalysts. The hyphomycetes, Aspergillus terreus CCT 3320 and A. terreus URM 3571, catalysed the oxidation of 2 accompanied by the reduction of 1 to 4-methylcyclohexanol 1a and, for strain A. terreus CCT 3320, the Baeyer-Villiger oxidation of 1. The Basidiomycetes, Trametes versicolor CCB 202, Pycnoporus sanguineus CCB 501 and Trichaptum byssogenum CCB 203, catalysed the oxidation of 2 and the reduction 1, but no Baeyer-Villiger reaction products were detected. In contrast, Trametes rigida CCB 285 catalysed the biotransformation of 1 to 1a, exclusively, in the absence of any detectable sulfide oxidation reactions. The chemoselective reduction of (±)-2-(phenylthio)cyclohexanone 3 by T. rigida CCB 285 afforded exclusively the (+)-cis-(1R,2S) and (+)-trans-(1S,2S) diastereoisomers of 2-(phenylthio)cyclohexan-1-ol 3a in moderate yields (13% and 27%, respectively) and high enantiomeric excesses (>98%). Chemoselective screening for the reduction of a ketone and/or the oxidation of a sulfide group in one pot by whole cells of micro-organisms represents an attractive technique with applications in the development of synthesis of complex molecule bearing different functional groups.
ε-Caprolactone manufacture via efficient coupling Baeyer-Villiger oxidation with aerobic oxidation of alcohols
Du, Renfeng,Li, Haoran,Wang, Yongtao,Yao, Jia,Yuan, Haoran,Zhao, Chenxuan
, (2020/04/27)
To avoid the use of peracids oxidant or highly concentrated hydrogen peroxide which is potentially hazardous and explosive, herein, a new route to ε-caprolactone was developed in which molecule oxygen was employed as the terminal oxidant. The commercial available N-hydroxyphthalimide and ammonium cerium nitrate were used as the key catalysts for the increased yield of ε-caprolactone. For instance, the selectivity of ε-caprolactone was obtained 92 % with 85 % conversion of cyclohexanone which was comparable to the strategies using highly concentrated hydrogen peroxide. The sacrificed alcohols were transformed into corresponding ketones which were also valuable chemicals. Furthermore, the efficiency of the alcohols was achieved to unprecedented 52 %. The Baeyer-Villiger oxidation of various other cycloalkanones was also examined. The substituent group effect on the efficiency of sacrificed alcohols was investigated in which weak electron-donating substituent induced nearly quantitative yield of ε-caprolactone. The reaction mechanism was studied with the help of electron paramagnetic resonance which indicated the existence of a radical pathway.
Oxidative Cleavage of Methyl Ethers Using the HOF*CH3CN Complex
Rozen, Shlomo,Dayan, Sharon,Bareket, Yifat
, p. 8267 - 8269 (2007/10/03)
HOF*CH3CN complex, made easily by bubbling fluorine diluted with nitrogen through aqueous acetonitrile, proved to be a suitable oxidizer for various methyl ethers.Secondary ethers are oxidized to ketones and even to lactones via Baeyer-Villiger type of oxidation.The reaction is ionic, and the reagent's electrophilic oxygen attacks the relatively electron rich C-H bond α to the ether moiety.It was found that the more sterically hindered is the C-H bond in question, the slower the reaction.In cases where this bond is an electron poor one as in benzoin methyl ether (9), no reaction takes place.When labeled H(18)OF*CH3CN is used on a (16)O methyl ether, the resulting ketone possesses only the heavier oxygen isotope.Primary methyl ethers are somewhat slower to react, but they too were oxidized in very good yields to acids via the corresponding aldehydes.
