- Palladium-Catalyzed Asymmetric Hydroesterification of α-Aryl Acrylic Acids to Chiral Substituted Succinates
-
A palladium-catalyzed asymmetric hydroesterification of α-aryl acrylic acids with CO and alcohol was developed, preparing a variety of chiral α-substituted succinates in moderate yields with high ee values. The kinetic profile of the reaction progress revealed that the alkene substrate first underwent the hydroesterification followed by esterification with alcohol. The origin of the enantioselectivity was elucidated by density functional theory computation.
- Ji, Xiaolei,Shen, Chaoren,Tian, Xinxin,Dong, Kaiwu
-
p. 8645 - 8649
(2021/10/25)
-
- Synthesis method of butyrolactone compound
-
The invention relates to a synthesis method of a butyrolactone compound. The synthesis method comprises the following step: in the presence of a solvent and a cobalt catalyst, converting an oxetane compound shown as general formula I into a butyrolactone compound shown as general formula II through carbonyl insertion ring expansion reaction in an atmosphere of CO and H2. Compared with an existingmethod for synthesizing butyrolactone through oxetane carbonylation ring expansion reaction in a carbon monoxide atmosphere, the synthesis method of a butyrolactone compound provided by the inventionhas the advantages of excellent catalytic activity, excellent chemical selection, wide substrate applicability, mild reaction conditions and the like; compared with other methods for synthesizing butyrolactone compounds, the method provided by the invention has the advantages of wide substrate range, high atom economy, no need of noble metal catalysis and the like, therefore the method has a wideapplication prospect.
- -
-
Paragraph 0019-0054
(2020/07/21)
-
- Efficient Synthesis of γ-Lactones by Cobalt-Catalyzed Carbonylative Ring Expansion of Oxetanes under Syngas Atmosphere
-
A practical route from oxetane or thietane to γ-(thio)butyrolactone via solvated-proton-assisted cobalt-catalyzed carbonylative ring expansion under syngas atmosphere has been established. A wide variety of γ-(thio)butyrolactones can be afforded in good to excellent yields. The versatility of this method has been well demonstrated in the synthesis of intermediates towards the natural product Arctigenin as well as the pharmaceuticals Baclofen and Montelukast. The observed promoting effect of glycol ether solvent has been rationally interpreted.
- Tang, Yitian,Shen, Chaoren,Yao, Qiyi,Tian, Xinxin,Wang, Bo,Dong, Kaiwu
-
p. 5898 - 5902
(2020/10/02)
-
- Enantioselective Rh-Catalyzed Anti-Markovnikov Hydroformylation of 1,1-Disubstituted Allylic Alcohols and Amines: An Efficient Route to Chiral Lactones and Lactams
-
Rh-catalyzed highly enantioselective anti-Markovnikov hydroformylation of 1,1-disubstituted allylic alcohols and amines has been achieved. By using a chiral hybrid phosphorus ligand, a series of challenging 1,1-disubstituted allylic alcohols and amines we
- You, Cai,Li, Shuailong,Li, Xiuxiu,Lv, Hui,Zhang, Xumu
-
p. 8529 - 8533
(2019/09/12)
-
- Visible-Light Photoredox-Catalyzed Hydroalkoxymethylation of Activated Alkenes Using α-Silyl Ethers as Alkoxymethyl Radical Equivalents
-
A new neutral silicon-based traceless activation group (TAG) for visible-light photoredox-catalyzed hydroalkoxymethylation of alkenes is presented. This reaction involves in-situ-generated alkoxymethyl radical via single electron oxidation (SET) of α-TMS-substituted ethers, followed by subsequent conjugate addition to activated alkenes. Various functional groups were tolerated both under mild metal and metal-free conditions to provide good to excellent yields. Furthermore, the addition products were transformed to valuable synthetic building blocks, such as carboxylic acids,-butyrolactones, and complex aryl alkyl ethers.
- Khatun, Nilufa,Kim, Myeong Jun,Woo, Sang Kook
-
supporting information
p. 6239 - 6243
(2018/09/27)
-
- Determination of the absolute configuration of two αvβ6 integrin inhibitors for the treatment of idiopathic pulmonary fibrosis and investigations on the asymmetric 1,4-addition of arylboronic acids to crotonate esters bearing a C4-oxygen substituent
-
The absolute configuration of two novel αvβ6 integrin inhibitors was established via degradation to the corresponding C3-aryl substituted butyrolactone. The configuration of the resulting lactones was established by asymmetric synthesis using 1,4-addition of arylboronic acids to butenolide, catalysed by bis(norbornadiene)rhodium (I) tetrafluoroborate in the presence of (R)-BINAP, and confirmed by X-ray crystallography. Studies on arylboronic acid conjugate additions to acyclic crotonate esters bearing a γ-oxygen substituent are also reported. Three Rh catalysts were investigated and the one giving the highest enantioselectivity was bis(norbornadiene)rhodium (I) tetrafluoroborate.
- Procopiou, Panayiotis A.,Barrett, Tim N.,Copley, Royston C.B.,Tame, Christopher J.
-
p. 1384 - 1393
(2017/11/09)
-
- Manipulating the stereoselectivity of the thermostable Baeyer-Villiger monooxygenase TmCHMO by directed evolution
-
Baeyer-Villiger monooxygenases (BVMOs) and evolved mutants have been shown to be excellent biocatalysts in many stereoselective Baeyer-Villiger transformations, but industrial applications are rare which is partly due to the insufficient thermostability o
- Li, Guangyue,Fürst, Maximilian J. L. J.,Mansouri, Hamid Reza,Ressmann, Anna K.,Ilie, Adriana,Rudroff, Florian,Mihovilovic, Marko D.,Fraaije, Marco W.,Reetz, Manfred T.
-
p. 9824 - 9829
(2017/12/08)
-
- Baeyer–Villiger monooxygenase-catalyzed desymmetrizations of cyclobutanones. Application to the synthesis of valuable spirolactones
-
A series of γ-butyrolactone derivatives, including some spiranic ones, was obtained through desymmetrization of the corresponding prochiral 3-substituted cyclobutanones via Baeyer–Villiger monooxygenase (BVMO)-catalyzed oxidation. After reaction optimization using several commercial enzymes, both antipodes of various lactones were synthesized in most cases with >90% conversion and >80% enantiomeric excess under mild reaction conditions. In some cases alcohol formation was also observed (up to 40% conversion) as an undesired side reaction due to the presence of alcohol dehydrogenases in these preparations. Selected transformations were achieved on a 100 mg scale showing the possibilities of these oxidative biocatalysts as a new source of highly interesting compounds.
- Rodríguez-Mata, María,Lavandera, Iván,Gotor-Fernández, Vicente,Gotor, Vicente,García-Cerrada, Susana,Mendiola, Javier,de Frutos, óscar,Collado, Iván
-
p. 7268 - 7275
(2016/10/26)
-
- Lactonization reactions through hydrolase-catalyzed peracid formation. Use of lipases for chemoenzymatic Baeyer-Villiger oxidations of cyclobutanones
-
A one-pot chemoenzymatic method has been described for the synthesis of γ-butyrolactones starting from the corresponding ketones through a Baeyer-Villiger reaction. The approach is based on a lipase-catalyzed perhydrolysis for the formation of peracetic acid, which is the responsible for the ketone oxidation. Optimization studies have been performed in the oxidation of cyclobutanone, finding Candida antarctica lipase type B, ethyl acetate and urea-hydrogen peroxide complex as the best system. The relative ratio of these reagents has also been analyzed in depth. This synthetic approach has been successfully extended to a family of 3-substituted cyclobutanones in high substrate concentration, yielding the corresponding lactones with excellent isolated yields and purities, under mild reaction conditions and after a simple extraction protocol.
- González-Martínez, Daniel,Rodríguez-Mata, María,Méndez-Sánchez, Daniel,Gotor, Vicente,Gotor-Fernández, Vicente
-
-
- Stable chiral complexes of ionic liquids with Aluminium and biaryl ligands as efficient catalysts for the synthesis of chiral lactones
-
A new catalytic system for the asymmetric Baeyer-?Villiger oxidation of monosubstituted prochiral cyclobutanones to γ-butyrolactones with high yields (40-99%) and enantioselectivities (45-87%) is described. Aluminium complexes with biaryl ligands and ioni
- Drozdz, Agnieszka,Foreiter, Magdalena B.,Chrobok, Anna
-
p. 559 - 563
(2014/03/21)
-
- Type II flavin-containing monooxygenases: A new class of biocatalysts that harbors baeyer-villiger monooxygenases with a relaxed coenzyme specificity
-
Within a newly identified set of flavin-containing monooxygenases (FMOs) from Rhodococcus jostii RHA1, we have identified three monooxygenases (FMO-E, FMO-F, and FMO-G) that are effective in catalyzing Baeyer-Villiger oxidations. These type II FMOs display relaxed coenzyme specificity by accepting both NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) and NADH (reduced form of nicotinamide adenine dinucleotide), as a coenzyme, which is a novel and attractive feature among biocatalysts capable of conducting Baeyer-Villiger oxidations. We purified FMO-E and determined that the Michaelis constants for both coenzymes were in the micromolar range, whereas the activity was highest for NADH. By using the stopped-flow technique, formation of a peroxyflavin-enzyme intermediate was observed, which indicated that type II FMOs follow a catalytic mechanism similar to that of other class B flavoprotein monooxygenases. A set of cyclobutanones and cyclohexanones were used to probe the regio- and enantioselectivity of all three recombinant monooxygenases. The biocatalysts readily accepted small cyclic ketones, which enabled the conversion of previously poorly accepted substrates by other monooxygenases (especially norcamphor), and exhibited excellent and unique regio- and enantioselectivities. Sequence analysis revealed that type II FMOs that act as Baeyer-Villiger monooxygenases contain a unique N-terminal domain. Sequence conservation in this protein domain can be used to identify new NADH-dependent Baeyer-Villiger monooxygenases, which would facilitate future biocatalyst discovery efforts. New kid on the block: Members of a newly recognized group of sequence-related flavin-containing monooxygenases can perform Baeyer-Villiger oxidations. Their coenzyme indifference and unique specificity make them attractive biocatalysts.
- Riebel, Anette,Fink, Michael J.,Mihovilovic, Marko D.,Fraaije, Marco W.
-
p. 1112 - 1117
(2014/05/06)
-
- Silyl peroxides as effective oxidants in the Baeyer-Villiger reaction with chloroaluminate(III) ionic liquids as catalysts
-
A new application of silyl peroxides as oxidants in the Baeyer-Villiger oxidation of cyclic ketones in chloroaluminate(III) ionic liquids is described. Among the silyl peroxides, the reactivity of two groups of peroxides was studied: bis(silyl) and t-butyl silyl peroxides possessing different structured substituents attached to the Si atom. It was shown that the acidic 1-hexyl-3-methylimidazolium chloroaluminate(III) ionic liquid (molar ratio of AlCl3 in ionic liquid: 0.67) present in the oxidation of cyclic ketones with bis(silyl) peroxides acts as the catalyst. In this variant of the reaction, the reactivities of bis(silyl) peroxides decrease in the following order: bis(trimethylsilyl) peroxide > bis(vinyldimethylsilyl) peroxide > bis(phenyldimethylsilyl) peroxide > bis(diphenylmethylsilyl) peroxide. A variety of cyclic ketones such as cyclobutanone, 3-substituted cyclobutanones, cyclopentanone, cyclohexanone, 2-methylcyclohexanone, 4-methylcyclohexanone, 2-adamantanone and norcamphor were oxidised to their corresponding lactones with high yields (49-100%). When t-butyl silyl peroxides and neutral chloroaluminate(III) ionic liquids (molar ratio of AlCl3 in ionic liquid: 0.5) were utilised in the Baeyer-Villiger oxidation, the studied ionic liquid acted as the reagent. Here, phenyldimethyl(t-butylperoxy)silane was the most efficient oxidant in the oxidation of cyclobutanone to γ- butyrolactone (70% yield). Other peroxides, including trimethyl(t-butylperoxy) silane, vinyldimethyl(t-butylperoxy)silane and diphenylmethyl-(t-butylperoxy) silane, were less reactive oxidants. Two variants of the Baeyer-Villiger reaction mechanism are postulated.
- Baj, Stefan,S?upska, Roksana,Chrobok, Anna,Drozdz, Agnieszka
-
p. 120 - 126
(2013/07/11)
-
- Intermolecular enantioselective Heck-Matsuda arylations of acyclic olefins: Application to the synthesis of β-aryl-γ-lactones and β-aryl aldehydes
-
We describe herein a synthetically useful method for the enantioselective intermolecular Heck-Matsuda arylation of acyclic allylic alcohols. Aryldiazonium tetrafluoroborates were applied as arylating agents in the presence of Pd(TFA)2 and a chiral, commercially available, bisoxazoline ligand. The methodology is straightforward, robust, scalable up to a few grams, and of broad scope allowing the synthesis of a range of β-aryl-carbonyl compounds in good to high enantioselectivities and yields. This new enantioselective Heck-Matsuda arylation allowed the synthesis of β-aryl-γ-lactones and β-aryl aldehydes, which play a vital role as key intermediates in the synthesis of the biologically active compounds, such as (R)-baclofen, (R)-rolipram, (S)-curcumene, (S)-dehydrocurcumene, and (S)-tumerone.
- Oliveira, Caio C.,Angnes, Ricardo A.,Correia, Carlos Roque D.
-
p. 4373 - 4385
(2013/06/27)
-
- Enantioselective baeyer-villiger oxidation: Desymmetrization of meso cyclic ketones and kinetic resolution of racemic 2-arylcyclohexanones
-
Catalytic enantioselective Baeyer-Villiger (BV) oxidations of racemic and meso cyclic ketones were achieved in the presence of chiral N,N'-dioxide-Sc III complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active μ- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratory aptitude, were obtained preferentially. Both the lactones and the unreacted ketones were obtained with high ee values.
- Zhou, Lin,Liu, Xiaohua,Ji, Jie,Zhang, Yuheng,Hu, Xiaolei,Lin, Lili,Feng, Xiaoming
-
supporting information
p. 17023 - 17026,4
(2012/12/12)
-
- Enantioselective baeyer-villiger oxidation: Desymmetrization of meso cyclic ketones and kinetic resolution of racemic 2-arylcyclohexanones
-
Catalytic enantioselective Baeyer-Villiger (BV) oxidations of racemic and meso cyclic ketones were achieved in the presence of chiral N,N'-dioxide-Sc III complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active μ- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratory aptitude, were obtained preferentially. Both the lactones and the unreacted ketones were obtained with high ee values.
- Zhou, Lin,Liu, Xiaohua,Ji, Jie,Zhang, Yuheng,Hu, Xiaolei,Lin, Lili,Feng, Xiaoming
-
supporting information
p. 17023 - 17026
(2013/01/15)
-
- Efficient asymmetric Baeyer-Villiger oxidation of prochiral cyclobutanones using new polymer-supported and unsupported chiral co(salen) complexes
-
Two heterogeneous catalysts 4 and 5 and three homogenous complexes 1-3 were prepared and used for enantioselective Baeyer-Villiger (B-V) oxidation of prochiral cyclobutanones. Among the prepared catalysts, the supported ones showed better enantioselectivi
- Sandaroos, Reza,Goldani, Mohammad Taghi,Damavandi, Saman,Mohammadi, Ali
-
p. 871 - 876,6
(2020/09/09)
-
- Baeyer-Villiger Oxidation of Cyclobutanones with 10-Methylacridinium as an Efficient Organocatalyst
-
Baeyer-Villiger oxidation of cyclobutanones is achieved in current developed protocol with 10-methylacridinium perchlorate (AcrH +ClO4-) as a novel organocatalyst both with irradiation at room temperature and without irradiation at elevated temperature. Excellent yields of the corresponding lactones are obtained and the possible mechanism has been proposed.
- Xu, Hua-Jian,Zhu, Feng-Fei,Shen, Yong-Ya,Wan, Xin,Feng, Yi-Si
-
p. 4145 - 4151
(2012/07/27)
-
- Palladium-catalyzed, asymmetric Baeyer-Villiger oxidation of prochiral cyclobutanones with PHOX ligands
-
Described in this report is a general method for the conversion of prochiral 3-substituted cyclobutanones to enantioenriched γ-lactones through a palladium-catalyzed Baeyer-Villiger oxidation using phosphinooxazoline ligands in up to 99% yield and 81% ee. Lactones of enantiopurity ≥93% could be obtained through a single recrystallization step. Importantly, 3,3-disubtituted cyclobutanones produced enantioenriched lactones containing a β-quaternary center.
- Petersen, Kimberly S.,Stoltz, Brian M.
-
experimental part
p. 4352 - 4357
(2011/07/29)
-
- Charge-transfer effect on chiral phosphoric acid catalyzed asymmetric Baeyer-Villiger oxidation of 3-substituted cyclobutanones using 30% aqueous H2O2 as the oxidant
-
The intermolecular charge-transfer effect has been employed for the first time as a modulating approach to affect the enantioselectivity in asymmetric catalysis by taking the chiral phosphoric acid catalyzed asymmetric Baeyer-Villiger oxidation of 3-aryl
- Xu, Senmiao,Wang, Zheng,Zhang, Xumu,Ding, Kuiling
-
experimental part
p. 1731 - 1735
(2011/07/08)
-
- Synthesis of quaternary carbon centers via hydroformylation
-
The application of hydroformylation to the synthesis of quaternary carbon centers is reported. The synthesis of the highly substituted carbon is achieved by applying a catalytic amount of 1. Ligand 1 serves as a catalytic directing group by covalently and reversibly binding to both the substrate and catalyst. The intramolecular nature of the directing group strategy accelerates the hydroformylation reaction such that the reaction is performed at mild temperatures (35-55 °C) and with excellent regioselectivity (b:l > 94:6).
- Sun,Frimpong,Tan
-
supporting information; experimental part
p. 11841 - 11843
(2010/11/04)
-
- Enantioselective baeyer-villiger oxidation catalyzed by palladium(II) complexes with chiral P,N-ligands
-
(Chemical Equation Presented) Asymmetric Baeyer-Villiger reaction of symmetrical cyclobutanones 1a-j with urea-hydrogen peroxide (UHP) can be catalyzed by a complex of Pd(II) and the new terpene-derived P,N-ligand 7. The resulting lactones 2a-j were obtained in high yields and with good enantioselectivity (≤81% ee).
- Malkov, Andrei V.,Friscourt, Frederic,Bell, Mark,Swarbrick, Martin E.,Kocovsky, Pavel
-
p. 3996 - 4003
(2008/09/20)
-
- Chiral Bronsted acid catalyzed asymmetric Baeyer-Villiger reaction of 3-substituted cyclobutanones by using aqueous H2O2
-
(Chemical Equation Presented) A catalytic amount of a chiral Bronsted acid with aqueous H2O2 as the oxidant is sufficient for the enantioselective Baeyer-Villiger oxidation of 3-substituted cyclobutanones to give the corresponding γ-
- Xu, Senmiao,Wang, Zheng,Zhang, Xue,Zhang, Xumu,Ding, Kuiling
-
p. 2840 - 2843
(2008/12/23)
-
- Self-sufficient Baeyer-Villiger monooxygenases: Effective coenzyme regeneration for biooxygenation by fusion engineering
-
(Chemical Presented) Two-in-one biocatalysts were engineered by the covalent fusion of NADPH-dependent Baeyer-Villiger monooxygenases to a phosphite dehydrogenase for coenzyme regeneration (see scheme). Not only the purified fusion proteins, but also whole cells and crude cell extracts containing the enzyme conjugates, could be used to catalyze biotransformations with high efficiency. NADP+=nicotinamide adenine dinucleotide phosphate.
- Torres Pazmino, Daniel E.,Snajdrova, Radka,Baas, Bert-Jan,Ghobrial, Michael,Mihovilovic, Marko D.,Fraaije, Marco W.
-
supporting information; scheme or table
p. 2275 - 2278
(2009/02/08)
-
- Comparing the stereoselective biooxidation of cyclobutanones by recombinant strains expressing bacterial baeyer - Villiger monooxygenases
-
Microbial Baeyer - Villiger oxidation of representative prochiral ketones with a cyclobutanone structural motif was investigated using a collection of eight monooxygenases of different bacterial origin. This platform of enzymes is able to perform stereoselective biotransformations on an array of structurally diverse substrates. With several ketone precursors, biooxidations yielded enantiocomplementary butyrolactones as key intermediates for the synthesis of natural products and bioactive compounds. The microbial Baeyer - Villiger oxidation allows a facile and rapid entry to several compound classes in a desymmetrization reaction upon de novo generation of chirality.
- Rudroff, Florian,Rydz, Joanna,Ogink, Freek H.,Fink, Michael,Mihovilovic, Marko D.
-
p. 1436 - 1444
(2008/09/17)
-
- An aerobic, organocatalytic, and chemoselective method for Baeyer-Villiger oxidation
-
(Chemical Equation Presented) Highly chemoselective Baeyer-Villiger oxidations can be performed in the presence of other reactive functionalities such as alcohols, olefins, and sulfides, which would undergo electrophilic oxidation under conventional conditions (see scheme). [DMRFlEt] +[ClO4]- (depicted blue) is a new class of flavin compound that catalyzes aerobic Baeyer-Villiger oxidations in the presence of Zn dust as the electron source.
- Imada, Yasushi,Iida, Hiroki,Murahashi, Shun-Ichi,Naota, Takeshi
-
p. 1704 - 1706
(2007/10/03)
-
- Method for producing optically active lactone compounds by using salen cobalt complexes having a cis-beta structure
-
A method for producing an optically active lactone compound by Baeyer-Villiger oxidation of a cyclic ketone compound with at least one kind of oxidants selected from the group consisting of hydrogen peroxide and urine-hydrogen peroxide adduct (UHP) using a cobalt(salen) complex having a cis-β structure expressed by the following formula (I) or (II) as a catalyst. in which X and Y independently denote H, a t-butyl group or an electron-withdrawing substituting group and W is a halogen element. in which X and Y independently denote H, a t-butyl group or an electron-withdrawing substituting group and Z? is a monovalent anion. The optically active lactone compounds can be used for the synthesis of medicines and argochemicals.
- -
-
-
- Method of producing optically active lactone compound and complex used in the method
-
An optically active lactone compound is produced by using a Zr(salen) complex of the following formula (I) or its enantiomer as a catalyst and subjecting a cyclic ketone compound to a Baeyer-Villiger reaction with at least one oxidizer selected from hydrogen peroxide, aqueous hydrogen peroxide and urea-hydrogen peroxide adduct in a solvent: wherein Ar1 is an aryl group having a carbon number of 10 to 16 and Y is a phenoxy group or an alkoxy group having a carbon number of 1 to 10.
- -
-
-
- Asymmetric Baeyer-Villiger oxidation of cyclobutanones using diethylzinc / oxygen / chiral amino alcohols
-
A novel method for the asymmetric Baeyer-Villiger oxidation of cyclobutanones using diethylzinc/oxygen/chiral amino alcohols has been developed. The best result was obtained using (1R,2S)-N,N-diethylnorephedrine as the chiral ligand: 3-phenylcyclobutanone was converted into (S)-β-phenyl-γ-butyrolactone with 39% ee and in 75% chemical yield.
- Shinohara, Toshio,Fujioka, Shingo,Kotsuki, Hiyoshizo
-
p. 237 - 242
(2007/10/03)
-
- Reaction of 1,2-cyclic sulfites with some soft nucleophiles. Formation of enantiomerically pure γ-lactones
-
The reaction between 1,2-cyclic sulfites and soft carbon centered nucleophiles has been investigated. For monosubstituted cyclic sulfites, the main products were γ-lactones or acetoxy esters. For 1,2-disubstituted cyclic sulfites, cyclopropanes, carbonate and dioxolanes were the main products. A mechanistic rationale for the product formation is presented. Acta Chemica Scandinavica 1998.
- Nymann, Kirsten,Svendsen, John S.
-
p. 338 - 349
(2007/10/03)
-
- Asymmetric Baeyer-Villiger reaction: Diastereodifferentiating peracid oxidation of chiral acetal in the presence of Lewis acid
-
Oxidation of 2 with m-chloroperbenzoic acid in the presence of SnCl4 at -78°C followed by hydrolysis afforded optically active 4 in a quantitative yield. The enantiomeric excess tee) of 4 largely depended on the reaction solvent, the chiral dio
- Sugimura, Takashi,Fujiwara, Yoshihisa,Akira, Tai
-
p. 6019 - 6022
(2007/10/03)
-
- A chemoenzymatic strategy for the synthesis of enantiopure (R)-(-)-baclofen
-
A seven-step enantioselective synthesis of (R)-(-)-baclofen 1 is described. The strategy developed involved as a key step, a microbiologically mediated Baeyer Villiger oxidation of the prochiral 3-(4'-chlorobenzyl)-cyclobutanone 3 which led to the optically pure (R)-(-)-4 lactone. This was further transformed throughout chemospecific reactions into the target molecule (R)-(-)-1.
- Mazzini, Claudio,Lebreton, Jacques,Alphand, Veronique,Furstoss, Roland
-
p. 1195 - 1196
(2007/10/03)
-
- An expeditious synthesis of 4-aryl-γ-butyrolactones, -furan-2(5H)-ones and -5-alkoxyfuran-2(5H)-ones via Heck-reaction of arenediazonium salts with 2,5-dihydrofuran
-
An exceptionally simple and short synthetic sequence to 4-substituted furan-2(5H)-ones involving a Heck reaction on 2,5-dihydrofuran and subsequent iterative NBS oxidation is described.
- Mehta, Goverdhan,Sengupta, Saumitra
-
p. 8625 - 8626
(2007/10/03)
-
- Enantioselective Synthesis of Succinic Acids and γ-Lactones via Palladium Catalysed Allylic Substitution Reactions
-
The palladium catalyzed reaction between non-symmetrical allyl acetates and sodiodimethylmalonate proceeds in high yields and enantioselectivities (up to 99percent ee) using a diphenylphosphinoaryl oxazoline ligand.The so-formed substitution products are transformed into enantiomerically enriched succinic acids and also into enantiomerically enriched γ-lactones.
- Dawson, Graham J.,Williams, Jonathan M. J.,Coote, Steven J.
-
p. 2535 - 2546
(2007/10/03)
-
- A NEW SYNTHESIS OF trans-2-SUBSTITUTED-2-BUTENE-1,4-DIOLS FROM 2-BUTYNE-1,4-DIOL VIA NUCLEOPHILIC ADDITION OF GRIGNARD REAGENTS
-
trans-2-Substituted-2-butene-1,4-diols were readily obtained by reactions of 2-butyne-1,4-diol with Grignard reagents in good yields.
- Ishino, Yoshio,Wakamoto, Kohji,Hirashima, Tsuneaki
-
p. 765 - 768
(2007/10/02)
-
- Asymmetric Synthesis. Part 6. Copper Salt promoted Grignard Reagent Additions to Ethyl 2,3-Dideoxy-4,5:6,7-di-O-isopropylidene-D-arabino-trans-hept-2-enonate and subsequent Formation of Optically Active 2-Alkyl (or Aryl) Butane-1,4-dioic Acids and Butyro-1,4-lactones
-
The copper-salt promoted 1,4-additions of aryl and t-butyl Grignard reagents to ethyl 2,3-dideoxy-4,5:6,7-di-O-isopropylidene-D-arabino-trans-hept-2-enonate are highly stereoselective yielding products with the D-manno-configuration.In contrast isopropyl and ethyl Grignarg reagents give products preponderantly with the D-gluco-configuration.Cyclohexylmagnesium bromide does not react stereoselectively but gives a 55:45 mixture of the D-gluco- and D-manno-isomers.Controlled degradation of the carbohydrate molecule affords 2-aryl (alkyl) butane-1,4-dioic acids and 3-aryl (alkyl)-butyro-1,4-lactones.The enantiomeric purity of these products is established by reference to known products or by use of optically active n.m.r. shift reagents.
- Lawston, Ian W.,Inch, Thomas D.
-
p. 2629 - 2635
(2007/10/02)
-