- Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor-Independent Non-natural Peroxygenase
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Peroxygenases are heme-dependent enzymes that use peroxide-borne oxygen to catalyze a wide range of oxyfunctionalization reactions. Herein, we report the engineering of an unusual cofactor-independent peroxygenase based on a promiscuous tautomerase that accepts different hydroperoxides (t-BuOOH and H2O2) to accomplish enantiocomplementary epoxidations of various α,β-unsaturated aldehydes (citral and substituted cinnamaldehydes), providing access to both enantiomers of the corresponding α,β-epoxy-aldehydes. High conversions (up to 98 %), high enantioselectivity (up to 98 % ee), and good product yields (50–80 %) were achieved. The reactions likely proceed via a reactive enzyme-bound iminium ion intermediate, allowing tweaking of the enzyme's activity and selectivity by protein engineering. Our results underscore the potential of catalytic promiscuity for the engineering of new cofactor-independent oxidative enzymes.
- Crotti, Michele,Kataja, Kim M.,Poelarends, Gerrit J.,Saravanan, Thangavelu,Xu, Guangcai
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p. 10374 - 10378
(2020/04/23)
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- Asymmetric epoxidation of α,β-unsaturated aldehydes catalyzed by a spiro-pyrrolidine-derived organocatalyst
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The asymmetric epoxidation of α,β-unsaturated aldehydes, catalyzed by a spiro-pyrrolidine (SPD)-derived organocatalyst, has been accomplished with good diastereoselectivities (up to dr >20:1) and with high to excellent enantioselectivities (up to 99% ee).
- Xu, Ming-Hui,Tu, Yong-Qiang,Tian, Jin-Miao,Zhang, Fu-Min,Wang, Shao-Hua,Zhang, Shi-Heng,Zhang, Xiao-Ming
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p. 294 - 300
(2017/03/01)
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- Asymmetric epoxidation of α,β-unsaturated aldehydes in aqueous media catalyzed by resin-supported peptide-containing unnatural amino acids
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The enantio- and diastereoselective epoxidation of α,β- unsaturated aldehydes in aqueous media was realized using a resin-supported peptide catalyst. Introducing the hydrophobic and bulky unnatural amino acid 3-(1-pyrenyl)alanine into the peptide sequence was effective for enhancing the reaction rate and enantioselectivity.
- Akagawa, Kengo,Kudo, Kazuaki
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experimental part
p. 843 - 847
(2011/06/11)
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- Stereoselective synthesis of (2S,3R)- and (2R,3S)-iodoreboxetine; Potential SPECT imaging agents for the noradrenaline transporter
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With the aim of developing a new SPECT imaging agent for the noradrenaline transporter, a twelve-step stereoselective synthesis of iodinated analogues of (2S,3R)- and (2R,3S)-reboxetine has been achieved from 4-bromobenzaldehyde. The key steps involve a S
- Jobson, Nicola K.,Spike, Rosemary,Crawford, Andrew R.,Dewar, Deborah,Pimlott, Sally L.,Sutherland, Andrew
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experimental part
p. 2369 - 2376
(2009/02/02)
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- New approaches for the synthesis of isotopically labelled guanidine-derived amino acids and noradrenaline reuptake inhibitors
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A new approach for the stereoselective synthesis of guanidine-derived amino acids, L-arginine and (+)-blastidic acid, has been devised which allows the selective incorporation of isotopic labels in both the side chain of the amino acid as well as the guanidine unit. A new asymmetric synthesis of the (S,R)-diastereomer of reboxetine, an antidepressant, has also been completed which allows the specific incorporation of radiolabelled iodine for SPECT imaging. Copyright
- Bischoff, Roland,Hamilton, Deborah J.,Jobson, Nicola K.,Sutherland, Andrew
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p. 323 - 326
(2008/02/05)
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- Amine-catalyzed asymmetric epoxidation of α,β-unsaturated aldehydes
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The direct organocatalytic enantioselective epoxidation of α,β-unsaturated aldehydes with different peroxides is presented. Proline, chiral pyrrolidine derivatives, and amino acid-derived imidazolidinones catalyze the asymmetric epoxidation of α,β-unsatur
- Zhao, Gui-Ling,Ibrahem, Ismail,Sunden, Henrik,Cordova, Armando
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p. 1210 - 1224
(2008/09/17)
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- Catalytic Asymmetric Epoxidation and Kinetic Resolution: Modified Procedures Including in Situ Derivatization
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The use of 3A or 4A molecular sieves ( zeoiltes ) substantially increases the scope of the titanium(IV)-catalyzed asymmetric epoxidation of primary allylic alcohols.Whereas without molecular sieves epoxidations employing only 5 to 10 mol percent Ti(O-i-Pr)4 generally led to low conversion or low enantioselectivity, in the presence of molecular sieves such reactions generally led to high conversion (>95percent) and high enantioselectivity (90-95percent ee).The epoxidations of 20 primary allylic alcohols are described.Especially noteworthy are the epoxidations of cinnamyl alcohol, 2-tetradecyl-2-propen-1-ol, allyl alcohol, and crotyl alcohol-compounds which heretofore had been considered difficult substrates for asymmetric epoxidation.In the case of allylic alcohol, the use of cumene hydroperoxide substantially increases both the reaction rate and the conversion, even in the absence of molecular sieves.In general, enantioselectivities are slightly depressed (by 1-5percent ee) relative to reactions employing 50-100 mol percent Ti(O-i-Pr)4.The epoxidation of low molecular weight allylic alcohols is especially facilitated and, in conjuction with in situ derivatization, provides for the synthesis of many epoxy alcohol synthons which were previously difficult to obtain.The kinetic resolution of four secondary allylic alcohols with 10 mol percent Ti(O-i-Pr)4 is also described.The role of molecular sieves in the reaction and the effects of variation in reaction stoichiometry, oxidant, and tartrate are discussed.
- Gao, Yun,Hanson, Robert M.,Klunder, Janice M.,Ko, Soo Y.,Masamune, Hiroko,Sharpless, K. Barry
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p. 5765 - 5780
(2007/10/02)
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