- DXP reductoisomerase: Reaction of the substrate in pieces reveals a catalytic role for the nonreacting phosphodianion group
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The role of the nonreacting phosphodianion group of 1-deoxy-d-xylulose-5- phosphate (DXP) in catalysis by DXP reductoisomerase (DXR) was investigated for the reaction of the substrate in pieces . The truncated substrate 1-deoxy-l-erythrulose is converted by DXR to 2-C-methylglycerol with a k cat/Km that is 106-fold lower than that for DXP. Phosphite dianion was found to be a nonessential activator, providing 3.2 kcal/mol of transition state stabilization for the truncated substrate. These results implicate a phosphate-driven conformational change involving loop closure over the DXR active site to generate an environment poised for catalysis.
- Kholodar, Svetlana A.,Murkin, Andrew S.
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- Molybdenum-Catalyzed Hydroxyl-Directed Anti-Dihydroxylation of Allylic and Homoallylic Alcohols
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A catalytic hydroxyl-directed anti-dihydroxylation of allylic and homoallylic alcohols has been developed. This operationally simple method was successfully applied to the direct anti-monodihydroxylation of allylic alcohols containing at least one distal olefinic unit. Under the catalysis of commercially available MoO2(acac)2, an array of hydroxylated dienes were successfully converted into various 1,2,3-triols using hydrogen peroxide as an environmentally benign oxidant under aerobic conditions, notably, in complete regioselectivities and in the most cases in diastereospecific pathway.
- Fan, Pei,Su, Shixia,Wang, Chuan
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p. 6820 - 6826
(2018/06/22)
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- The role of phosphate in a multistep enzymatic reaction: Reactions of the substrate and intermediate in pieces
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Several mechanistically unrelated enzymes utilize the binding energy of their substrate's nonreacting phosphoryl group to accelerate catalysis. Evidence for the involvement of the phosphodianion in transition state formation has come from reactions of the substrate in pieces, in which reaction of a truncated substrate lacking its phosphorylmethyl group is activated by inorganic phosphite. What has remained unknown until now is how the phosphodianion group influences the reaction energetics at different points along the reaction coordinate. 1-Deoxy-d-xylulose-5-phosphate (DXP) reductoisomerase (DXR), which catalyzes the isomerization of DXP to 2-C-methyl-d-erythrose 4-phosphate (MEsP) and subsequent NADPH-dependent reduction, presents a unique opportunity to address this concern. Previously, we have reported the effect of covalently linked phosphate on the energetics of DXP turnover. Through the use of chemically synthesized MEsP and its phosphate-truncated analogue, 2-C-methyl-d-glyceraldehyde, the current study revealed a loss of 6.1 kcal/mol of kinetic barrier stabilization upon truncation, of which 4.4 kcal/mol was regained in the presence of phosphite dianion. The activating effect of phosphite was accompanied by apparent tightening of its interactions within the active site at the intermediate stage of the reaction, suggesting a role of the phosphodianion in disfavoring intermediate release and in modulation of the on-enzyme isomerization equilibrium. The results of kinetic isotope effect and structural studies indicate rate limitation by physical steps when the covalent linkage is severed. These striking differences in the energetics of the natural reaction and the reactions in pieces provide a deeper insight into the contribution of enzyme-phosphodianion interactions to the reaction coordinate.
- Kholodar, Svetlana A.,Allen, C. Leigh,Gulick, Andrew M.,Murkin, Andrew S.
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p. 2748 - 2756
(2015/03/04)
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- Chemoenzymatic enantioselective synthesis of 2-substituted glycerol derivatives
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2-Substituted glycerol derivatives 4a-g were resolved by acylation with vinyl butyrate in the presence of lipases in organic media. The reverse reaction, the enzymatic hydrolysis of the corresponding butyrates 5a-g, was also highly stereoselective and pro
- Bolduc, Melanie,Bergeron, Jerome,Michaud, Annie,Pelchat, Nicholas,Morin, Pierre,Dasser, Mohammed,Chenevert, Robert
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experimental part
p. 428 - 433
(2012/07/28)
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- Development of a multikilogram synthesis of a chiral epoxide precursor to a CCR1 antagonist. Use of in situ monitoring for informed optimisation via fragile intermediates
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The optimisation and scale up of a manufacturing route to a key intermediate, acetic acid 4-acetylamino-3-(2-methyl-oxiranyl- methoxy)phenyl ester (2), utilising a SNAr coupling, the hydro- genation of a nitro moiety and the conversion of a chi
- Ange, Debra,Booker, James E. M.,Pedge, Nicholas,Sinclair, Rhona,Sleigh, Chris,Stefinovic, Marijan,Vaz, Luis-Manuel,Way, Edward
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experimental part
p. 72 - 84
(2010/05/02)
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- USE OF INTERMEDIATES ((R ) -2,2, 4-TRIMETHYL-L, 3-DIOXOLANE-4-YL) METHANOL (A), 3-F LUORO-4-NITRO-PHENOL (B) AND 1- (4-CHLORO- BENZYL) -PIPERIDIN-4-YLAMINE (C)
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The present invention relates to novel processes for the preparation of intermediate compounds which can be used to prepare therapeutic agents. The present invention also relates to novel intermediate compounds which can be used to prepare therapeutic agents. More specifically, the invention relates to the use of intermediates ((R) -2,2,4-trimethyl-l, 3- dioxolane-4 -yl) methanol (A), 3-f luoro-4-nitro-phenol (B) and 1- (4-chloro-benZyl) -piperidin-4-ylamine (C).
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Page/Page column 4; 13
(2009/04/25)
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- Enantioselective synthesis of tertiary alcohols by the desymmetrizing benzoylation of 2-substituted glycerols
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(Chemical Equation Presented) Complementary catalysts have been found for the enantioselective desymmetrization of 2-substituted glycerols by monobenzoylation with benzoyl chloride and Et3N to give chiral tertiary alcohols with 80 to 94% ee (se
- Jung, Byunghyuck,Hong, Mi Sook,Kang, Sung Ho
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p. 2616 - 2618
(2008/02/13)
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- Facile synthesis of C2-symmetric chiral crown ethers with two reactive hydroxymethyl groups
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Two C2-symmetric chiral crown ethers, (2S,12S)-2,12- bis(hydroxymethyl)-2,12-dimethyl-18-crown-6 and (2R,9R)-2,9-bis(hydroxymethyl)- 2,9-dimethyl-18-crown-6 were synthesized from a chiral subunit, [(45)-2,2,4-trirnethyl-1,3-dioxolane-4-yl]methanol, at high enantiomeric purity over several steps. This synthetic method offers the potential to construct a variety of C2-symmetric chiral crown ethers using diverse combinations of building blocks. Georg Thieme Verlag Stuttgart.
- Nakatsuji, Yohji,Nakahara, Yoshio,Nagamiya, Katsumori,Itoh, Yuki,Uesugi, Kentaro,Ishida, Naohisa,Muraoka, Masahiro,Kida, Toshiyuki,Akashi, Mitsuru
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p. 2973 - 2978
(2008/03/13)
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- Sterically Hindered Triacylglycerol Analogues as Potent Inhibitors of Human Digestive Lipases
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A novel class of inhibitors of human digestive lipases have been developed. Various sterically hindered triacylglycerols based on 2-methyl- and 2-butylglycerol, and/or 2-methyl fatty acids were synthesized. The triacylglycerol analogues were tested for their ability to form stable monomolecular films at the air/water interface by recording their surface-pressure/molecular-area compression isotherms. The inhibition of human pancreatic and gastric lipases by the sterically hindered triacylglycerol analogues was studied by using the monolayer technique with mixed films of 1,2-dicaprin, which contained variable proportions of each inhibitor. Triolein analogues that contain a butyl group at the 2-position of the glycerol backbone or methyl groups both at the 2-position of glycerol, and the α-position of each oleic acid residue were potent inhibitors; this caused a 50% decrease in HPL activity at 0.003 molar fraction.
- Constantinou-Kokotou, Violetta,Magrioti, Victoria,Verger, Robert
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p. 1133 - 1140
(2007/10/03)
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- Enantioselective hydrolysis of functionalized 2,2-disubstituted oxiranes with bacterial epoxide hydrolases
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The biohydrolysis of 2,2-disubstituted oxiranes bearing various oxygen functional groups was investigated using the epoxide hydrolase activity of 11 bacterial strains. The results show that the activity and the selectivity strongly depend on the substrate structure and the biocatalyst. Whereas substrates possessing free hydroxyl groups were not transformed, their analogs, protected as ethers, were well accepted. This allowed the convenient modulation of the enantioselectivity by proper choice of the ether group according to size and polarity. It was found that the distance of the ether-oxygen to the stereogenic quaternary carbon center of the oxirane ring had a profound influence on the enantioselectivity, and several oxiranes were resolved with good to excellent selectivities. The enantiomerically enriched epoxides and vicinal diols thus obtained contain a useful 'synthetic handle' in their side chain, which allows their use as building blocks in asymmetric synthesis.
- Steinreiber, Andreas,Osprian, Ingrid,Mayer, Sandra F.,Orru, Romano V. A.,Faber, Kurt
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p. 3703 - 3711
(2007/10/03)
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- Facile Chemoenzymatic Preparation of Enantiomerically Pure 2-Methylglycerol Derivatives as Versatile Trifunctional C4-Synthons
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Both enantiomers of a series of synthetically valuable 2-methylglycerol derivatives have been prepared with >99percent ee using a chemoenzymatic reaction sequence.The introduction of chirality was achieved by enantioselective esterification of 1,2-O-protected 2-methylglycerol 3 or enantioselective hydrolysis of its butyryl ester 4.The enzymatic reaction proceeded with unusually high selectivity and velocity for a primary alcohol (ester) substrate.
- Wirz, Beat,Barner, Richard,Huebscher, Joseph
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p. 3980 - 3984
(2007/10/02)
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- BRANCHED-CHAIN DERIVATIVES OF ACYCLIC ADENOSINE ANALOGS: ALKYL AND HYDROXYMETHYL DERIVATIVES OF S-ADENOSYL-L-HOMOCYSTEINASE INHIBITORS SUBSTITUTED AT THE 2- AND 3-POSITION OF THE SIDE CHAIN
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Reaction of 1,3-dichloro-2-propanone (VII) with methylmagnesium chloride, followed by alkaline hydrolysis, afforded 2-methylpropane-1,2,3-triol (VIII) which on treatment with 2,2-dimethoxypropane and subsequent tosylation give 4-(p-toluenesulfonyloxymethyl)-2,2,4-trimethyl-1,3-dioxolane (IXb).Compound IXb was condensed with sodium salt of adenine and the intermediate X was acid-hydrolysed to give 9-(RS)-(2,3-dihydroxy-2-methylpropyl)adenine (XI).Oxidation of XI with sodium periodate led to 9-(2-oxopropyl)adenine (XII). 9-(RS)-(2-Hydroxy-2-hydroxymethyloctyl)adenine (XVI) was obtained analogously from compound VII and hexylmagnesium bromida via triol XIV.Methyl 2-bromomethyl-2-propenoate (XVII) reacted with sodium salt of adenine and the resulting methyl 2-(adenin-9-ylmethyl)-2-propenoate (XVIII) was hydroxylated with sodium perchlorate and osmium tetroxide.The obtained methyl (RS)-2-(adenin-9-ylmethyl)-2,3-dihydroxypropanoate (XIX) was alkali-hydrolysed to give sodium salt of the acid XX.Reduction of ester XIX with sodium borohydride furnished 9-(RS)-(2,3-dihydroxy-2-hydroxymethylpropyl)adenine (XXI). 1-Nonen-3-ol (XXIII), obtained by reaction of propenal with hexylmagnesium bromide, was converted by hydroxylation with osmium tetroxide into nonane-1,2,3-triol (XXIVa) and further into its 1-O-p-toluenesulfonate XXIVb which reacted with 2,2-dimethoxypropane to give 2,2-dimethyl-4-hexyl-5-(p-toluenesulfonyloxymethyl)-1,3-dioxolane (XXV).Compound XXV reacted with adenine and the resulting intermediate XXVI was converted into 9-(RS)-(2,3-dihydroxynonyl)adenine (XXVII) by acid hydrolysis. 9-(3-Methyl-2-buten-1-yl)adenine (XXVIII), obtained by alkylation of sodium salt of adenine with 1-bromo-3-methyl-2-butene, was oxidized with potassium permanganate in an acid medium to give 9-(3-hydroxy-2-oxo-3-methylbutyl)adenine (XXIX).This compound was converted into 9-(RS)-(2,3-dihydroxy-3-methylbutyl)adenine (XXX) by reduction with sodium borohydride. 4-C-Hydroxymethyl-1,2-O-isopropylidene-α-D-xylofuranose (XXXII) reacted with 2,2-dimethoxypropane under formation of 4-C-hydroxymethyl-1,2:3,5-di-O-isopropylidene derivative XXXIIIa whose p-toluenesulfonyl derivative XXXIIIb on treatment with adenine afforded 4-C-(adenin-9-yl)methyl-1,2:3,5-di-O-isopropylidene-α-D-xylofuranose (XXXIV).Acid hydrolysis of this compound, followed by oxidation in an alkaline medium, gave (2S,3R)-4-(adenin-9-yl)-3-hydroxymethyl-2,3-dihydroxybutanoic acid, isolated as its ethyl ester XXXVI.
- Holy, Antonin
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p. 248 - 265
(2007/10/02)
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- Regio- and Stereocontrolled Synthesis of Epoxy Alcohols and Triols from Allylic and Homoallylic Alcohols via Iodo Carbonates
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The regio- and stereoselective synthesis of cyclic iodo carbonates 1-10, resulting from allylic and homoallylic alcohols was investigated.These useful intermediates were easily hydrolyzed to epoxy alcohols 11-20 or triols 21-30, depending on the polymeric reagent employed (Amberlyst A 26 in the OH- or CO32- form, respectively).Stereochemical assignments were carried out by 13C NMR or 1H NMR correlations and by conversion of the compounds to products of known stereostructures.
- Bongini, Alessandro,Cardillo, Giuliana,Orena, Mario,Porzi, Gianni,Sandri, Sergio
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p. 4626 - 4633
(2007/10/02)
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