cas 63473-60-9, (R)-1-METHYL HYDROGEN 3-METHYLGLUTARATE

Articles about 63473-60-9Total 51 be found

Article title
Article abstract
Author
Journal number and time
Download

ENZYMES IN ORGANIC SYNTHESIS. 42. INVESTIGATION OF THE EFFECTS OF THE ISOZYMAL COMPOSITION OF PIG LIVER ESTERASE ON ITS STEREOSELECTIVITY IN PREPARATIVE-SCALE ESTER HYDROLYSES OF ASYMMETRIC SYNTHETIC VALUE.
The stereospecificities of the isozyme components of commercially available pig liver esterase have been shown to be essentially the same toward representative monocyclic and acyclic diester substrates. This removes previous concerns that the isozymal com
Lam,Brown,De Jeso,Lym,Toone,Jones
p. 4409 - 4411
(1988)
Read Online

ASYMMETRIC RING OPENING OF CYCLIC ACID ANHYDRIDES WITH LIPASE IN ORGANIC SOLVENTS
A lipase (Amano P) catalyzed the asymmetric ring opening of 3-substituted glutaric anhydride with 1-butanol to afford the R half esters having 60-91percentee.
Yamamoto, Kazuyoshi,Nishioka, Takaaki,Oda, Jun'ichi,Yamamoto, Yukio
p. 1717 - 1720
(1988)
Read Online

Cinchona alkaloid derivative modified Fe3O4nanoparticles for enantioselective ring opening of: Meso -cyclic anhydrides
In the present work, the molecular framework of quinidine was modified at the methoxy functional group of the C6′ carbon of the quinoline moiety with a long-chain carboxylic acid group (-COOH) and it was used as a capping agent during the synthesis of Fe3
Soni, Hemant P.,Tomer, Sanjiv O.
p. 2495 - 2507
(2022/02/11)

Synthesis of a CGRP Receptor Antagonist via an Asymmetric Synthesis of 3-Fluoro-4-aminopiperidine
A practical and efficient enantioselective synthesis of the calcitonin gene-related peptide receptor antagonist 1 has been developed. The key structural component of the active pharmaceutical ingredient is a syn-1,2-amino-fluoropiperidine 4. Two approaches were developed to synthesize this important pharmacophore. Initially, Ru-catalyzed asymmetric hydrogenation of fluoride-substituted enamide 8 enabled the synthesis of sufficient quantities of compound 1 to support early preclinical studies. Subsequently, a novel, cost-effective route to this intermediate was developed utilizing a dynamic kinetic asymmetric transamination of ketone 9. This synthesis also features a robust Ullmann coupling to install a bis-aryl ether using a soluble Cu(I) catalyst. Finally, an enzymatic desymmetrization of meso-diester 7 was exploited for the construction of the γ-lactam moiety in 1.
Molinaro, Carmela,Phillips, Eric M.,Xiang, Bangping,Milczek, Erika,Shevlin, Michael,Balsells, Jaume,Ceglia, Scott,Chen, Jiahui,Chen, Lu,Chen, Qinghao,Fei, Zhongbo,Hoerrner, Scott,Qi, Ji,De Lera Ruiz, Manuel,Tan, Lushi,Wan, Baoqiang,Yin, Jingjun
supporting information
p. 8006 - 8018
(2019/06/17)

Atropselective Synthesis of N,C-Bis(diphenylphosphanes) from Bridged 2-Arylindoles Based on Effective Point-to-Axial Asymmetric Inductions after an Unusual Dilithiation ⊥
An asymmetric methanolysis of glutaric anhydride and 6 ensuing steps gave veratrol-annulated dimethylcyclo-heptenone diastereomers with 99% ee; ring closures occurred by Friedel-Crafts acylations of carboxylic acids obtained by stereospecific hydrogenolyses of a pair of diastereomeric δ-lactones. The mentioned cycloheptenones and Ph-NH-NH2 underwent Fischer indole syntheses providing the tetracyclic indoles cis- and trans-14a, respectively. Double lithiations with BuLi and quenchings with ClPPh2 furnished the diphosphanes cis- and trans-15 with perfect (P)- and (M)-atropselectivity, respectively.
B?uerle, Felix,Brückner, Reinhard
supporting information
p. 9970 - 9975
(2019/12/24)

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides
A family of novel chloramphenicol base-amide organocatalysts possessing a NH functionality at C-1 position as monodentate hydrogen bond donor were developed and evaluated for enantioselective organocatalytic alcoholysis of meso-cyclic anhydrides. These structural diversified organocatalysts were found to induce high enantioselectivity in alcoholysis of anhydrides and was successfully applied to the asymmetric synthesis of (S)-GABOB.
Xu, Lingjun,Han, Shuwen,Yan, Linjie,Wang, Haifeng,Peng, Haihui,Chen, Fener
supporting information
p. 309 - 317
(2018/02/19)

Enantioselective acyl-transfer catalysis by fluoride ions
The asymmetric nucleophilic catalysis by fluoride ions at a carbon-based electrophile has been demonstrated for the first time. Using a library of ad hoc designed bifunctional phase-transfer catalysts in which both the anion and the cation are directly involved in the reaction, the desymmetrisation of meso-succinic and -glutaric anhydrides is possible.19F NMR spectroscopic studies support the intermediacy of an acyl fluoride intermediate.
Craig, Ryan,Litvajova, Mili,Cronin, Sarah A.,Connon, Stephen J.
supporting information
p. 10108 - 10111
(2018/09/18)

Toward the total synthesis of patellazole B: Synthesis of an advanced C1-C25 fragment corresponding to the macrocyclic skeleton
The patellazoles are a family of complex marine macrolides that exhibit potent cytotoxicity against cancer cell lines. However, despite extensive characterisation efforts, their full stereochemical assignment has remained elusive. We report our approach towards the synthesis-enabled structural elucidation of patellazole B (4), a 24-membered macrolide with 16 stereocentres and a signature thiazole-containing side chain. Our plan hinges upon isolating the unknown stereocentres into a single C20-C25 fragment to facilitate the flexible assembly of various possible diastereomers of an advanced C1-C25 fragment. Towards this end, a highly convergent and modular synthesis of one candidate diastereomer 37, corresponding to the patellazole B macrocyclic skeleton, has been achieved based on the strategic application of stereocontrolled aldol methodology, combined with Suzuki and Heck cross-coupling reactions.
Phillips, Andrew W.,Anketell, Matthew J.,Balan, Tudor,Lam, Nelson Y. S.,Williams, Simon,Paterson, Ian
supporting information
p. 6908 - 6913
(2018/10/02)

Toward aplyronine payloads for antibody-drug conjugates: Total synthesis of aplyronines A and D
The aplyronines are a family of antimitotic marine macrolides that disrupt cytoskeletal dynamics by dual targeting of both actin and tubulin. Given their picomolar cytotoxicity profile and unprecedented mode of action, the aplyronines represent an excellent candidate as a novel payload for the development of next-generation antibody-drug conjugates (ADCs) for cancer chemotherapy. Enabled by an improved second-generation synthesis of the macrolactone core 5, we have achieved the first total synthesis of the most potent congener aplyronine D together with a highly stereocontrolled synthesis of aplyronine A. To facilitate step economy, an adventurous site-selective esterification of the C7 hydroxyl group was performed to install the N,N,O-trimethylserine pharmacophore to directly afford aplyronines A and D. Toward the assembly of ADCs incorporating an aplyronine warhead, the C29-ester derivative 4 featuring an Fmoc-amino substituted linker attached to the actin-binding tail region was also prepared by adapting this flexible endgame.
An?i?ek, Nika,Williams, Simon,Housden, Michael P.,Paterson, Ian
p. 1343 - 1350
(2018/03/06)

Development of Bifunctional Thiourea Organocatalysts Derived from a Chloramphenicol Base Scaffold and their Use in the Enantioselective Alcoholysis of meso Cyclic Anhydrides
The synthesis of new chloramphenicol-base-derived thiourea organocatalysts, (1S,2R)-12 a–f and (1R,2R)-15 a–c, and their use in the enantioselective alcoholysis of meso-anhydrides are described. In particular, hemiesters afforded excellent enantioselectivities if low loadings of (1S,2R)-12 a–f were used. Almost no enantioselectivities were achieved with the use of (1R,2R)-15 a–c. This technique was used to synthesize (R)-(?)-baclofen.
Yan, Lin-Jie,Wang, Hai-Feng,Chen, Wen-Xue,Tao, Yuan,Jin, Kai-Jun,Chen, Fen-Er
p. 2249 - 2253
(2016/07/19)

Synthesis of cinchona alkaloid sulfonamide polymers as sustainable catalysts for the enantioselective desymmetrization of cyclic anhydrides
The Mizoroki-Heck polymerization of cinchona-based sulfonamide dimers and aromatic diiodides was investigated in the presence of a palladium catalyst, to obtain chiral polymers in high yields. An iodobenzenesulfonamide derivative of a cinchona alkaloid was also polymerized via self-polycondensation under the same reaction conditions. The catalytic activities of these chiral polymers were examined by using them as catalysts in the enantioselective desymmetrization of cyclic anhydrides.
Takata, Shohei,Endo, Yuta,Shahid Ullah, Mohammad,Itsuno, Shinichi
p. 72300 - 72305
(2016/08/09)

Stereoselective synthesis of two highly potent 5-oxo-ETE receptor antagonists
Enantioselective synthesis of highly potent 5-oxo-ETE receptor antagonists 5a and 6a with a high level of enantiomeric purity is described. The main feature of this work is the simple and efficient synthesis of the bi-functionalized 3-(S)-methyl-pentanedi
Nagendra Reddy, Chintam,Ye, Qiuji,Chourey, Shishir,Gravel, Sylvie,Powell, William S.,Rokach, Joshua
p. 6896 - 6899
(2015/11/27)

A new method for the preparation of non-terminal alkynes: Application to the total syntheses of tulearin A and C
Lactones are known to react with the reagent generated in situ from CCl4 and PPh3 in a Wittig-type fashion to give gem-dichloro-olefin derivatives. Such compounds are now shown to undergo reductive alkylation on treatment with organolithium reagents RLi to furnish acetylene derivatives bearing the substituent R at their termini (R=Me, n-, sec-, tert-alkyl, silyl); the reaction can be catalyzed with either Cu(acac)2 or Fe(acac)3/1,2-diaminobenzene. Two alkynol derivatives prepared in this way from readily accessible lactone precursors served as the key building blocks for the total syntheses of the cytotoxic marine macrolides tulearin A (1) and C (2). The assembly of these fragile targets hinged upon ring closing alkyne metathesis (RCAM) followed by a formal trans-reduction of the resulting cycloalkynes via trans-hydrosilylation/protodesilylation.
Lehr, Konrad,Schulthoff, Saskia,Ueda, Yoshihiro,Mariz, Ronaldo,Leseurre, Lucie,Gabor, Barbara,Fürstner, Alois
supporting information
p. 219 - 227
(2015/02/19)

Two potent OXE-R antagonists: Assignment of stereochemistry
5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is formed by the oxidation of 5-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-HETE), which is a major metabolite of enzymatic oxidation of arachidonic acid (AA). 5-Oxo-ETE is the most potent lipid chemoattractant for human eosinophils. Its actions are mediated by the selective OXE receptor, which is therefore an attractive target in eosinophilic diseases such as allergic rhinitis and asthma. Recently, we have reported two excellent OXE receptor antagonists that have IC50 values at low nanomolar concentrations. Each of these antagonists has a chiral center, and the isolation of the individual enantiomers by chiral high-performance liquid chromatography (HPLC) revealed that in each case one enantiomer is over 300 times more potent than the other. To unambiguously assign the stereochemistry of these enantiomers and to provide access to larger amounts of the active compounds for biological testing, we report here their total synthesis.
Patel, Pranav,Reddy, Chintam Nagendra,Gore, Vivek,Chourey, Shishir,Ye, Qiuji,Ouedraogo, Yannick P.,Gravel, Sylvie,Powell, William S.,Rokach, Joshua
supporting information
p. 815 - 819
(2014/08/05)

A family of novel bifunctional organocatalysts: Highly enantioselective alcoholysis of meso cyclic anhydrides and its application for synthesis of the key intermediate of P2X7 receptor antagonists
A family of novel squaramides/sulfamides based on 1,2-alkamine was developed as chiral bifunctional catalysts to promote the asymmetric alcoholysis of meso cyclic anhydrides. The hemiesters were obtained in high yield with up to 93% ee. The usefulness of this methodology was demonstrated in the asymmetric synthesis of the key intermediate of P2X7 receptor antagonists.
Yang, Hong-Jun,Xiong, Fang-Jun,Li, Jie,Chen, Fen-Er
p. 553 - 558
(2013/07/27)

Transformations of peroxide ozonolysis products of (R)-Menth-4-en-3-one in the presence of nitrogen-containing organic compounds
The results of ozonolysis of (R)-menth-4-en-3-one in methylene chloride, methanol, or their 1: 1 mixture in the presence of pyridine, triethylamine, or semicarbazide hydrochloride are reported. Probable schemes for the formation of ozonolysis products, in
Ishmuratov,Bannova,Latypova,Tukhvatshin,Kukovinets,Muslukhov,Tolstikov
p. 42 - 45
(2013/03/28)

Catalytic enantioselective desymmetrization of meso-glutaric anhydrides using a stable Ni2-schiff base catalyst
We describe the desymmetrization of meso-glutaric anhydrides to chiral hemiesters using a bench-stable homodinuclear Ni2-(Schiff base) complex as the catalyst in good to excellent yield (up to 99%) and enantioselectivity (up to 94%). Using the opposite enantiomer of the catalyst, we obtained the same yield and enantioselectivity with the opposite configuration, thereby gaining access to both hemiester enantiomers.
Gopinath, Purushothaman,Watanabe, Takumi,Shibasaki, Masakatsu
supporting information; experimental part
p. 1358 - 1361
(2012/04/23)

An efficient route to the musk odorant (R,Z)-5-muscenone via base-metal-catalysis
Muscenone is a valuable perfume ingredient consisting of a mixture of the E- and Z-isomers of 1 in racemic form as the major constituents. Among them, it is the (R,Z)-isomer, which exhibits the most favorable musk character and by far the lowest threshold; for these superior olfactory properties, pure (R,Z)-1 has recently been commercialized too. We present an efficient route to this precious compound based on an iron-catalyzed cross coupling reaction, a molybdenum-catalyzed alkyne metathesis for the formation of the macrocyclic ring, and a nickel-catalyzed semi-hydrogenation.
Lehr, Konrad,Fürstner, Alois
experimental part
p. 7695 - 7700
(2012/09/21)

Studies on catalytic enantioselective total synthesis of caprazamycin B: Construction of the western zone
We describe a simple and convenient synthesis of the western zone of caprazamycin B using two catalytic asymmetric reactions as key elements of our approach. Desymmetrization of 3-methylglutaric anhydride with the (S)-Ni 2-(Schiff base) complex as a catalyst furnished the chiral hemiester, and a thioamide-aldol reaction with mesitylcopper, (R,R)-Ph-BPE, and 2,2,5,7,8-pentamethylchromanol as a catalyst furnished the β-hydroxy thioamide in good yield and enantioselectivity. On further transformation, the thioamide functionality was converted to the corresponding β-hydroxy ester. Finally, a convergent synthesis of the western zone of caprazamycin B was achieved by connecting the hemiester, the β-hydroxy ester, and the 2,3,4-tri-O-methyl-l-rhamnose fragments.
Gopinath, Purushothaman,Watanabe, Takumi,Shibasaki, Masakatsu
p. 9260 - 9267,8
(2012/12/11)

Studies on catalytic enantioselective total synthesis of caprazamycin B: Construction of the western zone
We describe a simple and convenient synthesis of the western zone of caprazamycin B using two catalytic asymmetric reactions as key elements of our approach. Desymmetrization of 3-methylglutaric anhydride with the (S)-Ni 2-(Schiff base) complex as a catalyst furnished the chiral hemiester, and a thioamide-aldol reaction with mesitylcopper, (R,R)-Ph-BPE, and 2,2,5,7,8-pentamethylchromanol as a catalyst furnished the β-hydroxy thioamide in good yield and enantioselectivity. On further transformation, the thioamide functionality was converted to the corresponding β-hydroxy ester. Finally, a convergent synthesis of the western zone of caprazamycin B was achieved by connecting the hemiester, the β-hydroxy ester, and the 2,3,4-tri-O-methyl-l-rhamnose fragments.
Gopinath, Purushothaman,Watanabe, Takumi,Shibasaki, Masakatsu
p. 9260 - 9267
(2013/01/15)

CINCHONA-BASED BIFUNCTIONAL ORGANOCATALYSTS AND METHOD FOR PREPARING CHIRAL HEMIESTERS USING THE SAME
The present invention relates to cinchona-based bifunctional organocatalysts and methods for preparing chiral hemiesters using the same. More specifically, the present invention relates to methods for preparing chiral hemiesters from prochiral or meso cyclic acid anhydrides via desymmetrization, using bifunctional cinchona alkaloid catalysts comprising sulfonamide functional groups.
-
Page/Page column 18

(2011/09/20)

The immobilisation of chiral organocatalysts on magnetic nanoparticles: The support particle cannot always be considered inert
A systematic study concerning the immobilisation onto magnetic nanoparticles of three useful classes of chiral organocatalyst which rely on a confluence of weak, easily perturbed van der Waals and hydrogen bonding interactions to promote enantioselective
Gleeson, Oliver,Davies, Gemma-Louise,Peschiulli, Aldo,Tekoriute, Renata,Gun'Ko, Yurii K.,Connon, Stephen J.
scheme or table
p. 7929 - 7940
(2011/12/04)

Total synthesis of tulearin C
With the help of the smaller brother: Although alkyne metathesis will always be the little brother of alkene metathesis, it allows problems to be solved that are currently beyond reach of the more famous sibling. This notion is exemplified by the tulearin macrolides, which could only be selectively forged by ring-closing alkyne metathesis (RCAM)/transreduction using the latest generation of alkyne metathesis catalysts.
Lehr, Konrad,Mariz, Ronaldo,Leseurre, Lucie,Gabor, Barbara,Fuerstner, Alois
supporting information; experimental part
p. 11373 - 11377
(2012/01/11)

CINCHONA-BASED BIFUCNTIONAL ORGANOCATALYSTS AND METHOD FOR PREPARING CHIRAL HEMIESTERS USING THE SAME
The present invention relates to cinchona-based bifunctional organocatalysts and methods for preparing chiral hemiesters using the same. More specifically, the present invention relates to methods for preparing chiral hemiesters from prochiral or meso cyclic acid anhydrides via desymmetrization, using birunctional cinchona alkaloid catalysts comprising sulfonamide functional groups.
-
Page/Page column 42; 46

(2010/04/03)

Synthesis of both enantiomers of hemiesters by enantioselective methanolysis of meso cyclic anhydrides catalyzed by α-amino acid-derived chiral thioureas
(Figure presented) Both ureas and thioureas derived from l- or d-valine act as bifunctional organocatalysts able to induce the enantioselective alcoholysis of mono-, bi-, and tricyclic meso anhydrides. The desymmetrization occurs in near quantitative yields and excellent enantiomeric ratios (up to >99:1) under low catalyst loading. Both enantiomers of the hemiesters can be directly obtained by changing the configuration of the catalyst.
Manzano, Ruben,Andres, Jose M.,Muruzabal, Maria-Dolores,Pedrosa, Rafael
supporting information; scheme or table
p. 5417 - 5420
(2010/09/07)

Highly enantioselective desymmetrizations of meso-anhydrides
Readily available, low molecular cyclohexane-based organocatalysts promote highly enantioselective desymmetrizations of cyclic meso-anhydrides applying alcohols and benzyl mercaptan as nucleophiles. Both succinic and glutaric anhydrides furnished the corresponding products with up to 96% ee in mostly quantitative yields.
Schmitt, Ellen,Schiffers, Ingo,Bolm, Carsten
experimental part
p. 6349 - 6357
(2010/10/03)

Enantioselective alcoholysis of meso-glutaric anhydrides catalyzed by Cinchona-based sulfonamide catalysts
The bifunctional Cinchona-based sulfonamide catalysts showed the highest levels of enantioselectivity reported to date in the alcoholytic desymmetrization of meioglutaric anhydrides. Density functional theory (DFT) computational studies provide detailed insight into the observed sense of enantioselectivity. Moreover, detailed experimental studies and single crystal X-ray analysis confirmed that these bifunctional organocatalysts 3 do not form Hbonded self-aggregates in both solution and solid state. The synthetic utility of this methodology was also demonstrated in the synthesis of pharmaceutically important γ-amino acids, such as (S)-pregabalin. Of the many asymmetric syntheses of enantiomerically pure (S)-pregabalin reported to date, our synthesis requires the least number of and the simplest steps.
Park, Sang Eun,Nam, Eun Hye,Jang, Hyeong Bin,Oh, Joong Suk,Some, Surajit,Lee, Yong Seop,Song, Choong Eui
supporting information; experimental part
p. 2211 - 2217
(2010/11/19)

A novel cost-effective thiourea bifunctional organocatalyst for highly enantioselective alcoholysis of meso-cyclic anhydrides: Enhanced enantioselectivity by configuration inversion
A novel inexpensive thiourea bifunctional organocatalyst which can promote the highly enantioselective (up to 95% ee) alcoholysis of mesocyclic anhydrides has been developed. Computational studies on the catalytic process as well as a synthetic application of this new catalyst are also presented.
Wang, Su-Xi,Chen, Fen-Er
supporting information; scheme or table
p. 547 - 552
(2009/10/25)

Highly enantioselective desymmetrization of meso anhydrides by a bifunctional thiourea-based organocatalyst at low catalyst loadings and room temperature
(Chemical Equation Presented) Bifunctional (thio)urea-based cinchona alkaloid derivatives have been shown to promote highly efficient enantioselective desymmetrization reactions of meso anhydrides. The most selective of these catalysts is capable of the enantioselective methanolysis of succinic and glutaric anhydride derivatives to form hemiester products with >90% yield and enantiomeric excess at 1 mol % loading and ambient temperature.
Peschiulli, Aldo,Gun'ko, Yurii,Connon, Stephen J.
p. 2454 - 2457
(2008/09/19)

A highly reactive and enantioselective bifunctional organocatalyst for the methanolytic desymmetrization of cyclic anhydrides: Prevention of catalyst aggregation
(Chemical Equation Presented) Unprecedented reactivity and high stereoselectivity were observed in the ring opening of meso anhydrides under mild conditions with a cinchona-alkaloid-based sulfonamide catalyst (see scheme). Computation of the catalyst-transition-state analogue (right; gray C, white H, green F, blue N, red O, yellow S) provided insight into the origin of the stereoselectivity.
Oh, Sang Ho,Rho, Ho Sik,Lee, Ji Woong,Lee, Je Eun,Youk, Sung Hoon,Chin, Jik,Song, Choong Eui
supporting information; experimental part
p. 7872 - 7875
(2009/04/10)

Synthesis of the northern hemisphere of amphidinolide H2
The stereoselective synthesis of the fully functionalized northern hemisphere of the marine natural product amphidinolide H2 is described. A vinylogous Mukaiyama aldol reaction and enzymatic desymmetrization of a meso compound are the key steps in the fragment synthesis. A stereoselective acetate aldol coupling and a 1,3-anti-reduction of the resulting β-hydroxy ketone complete the synthesis of the C14-C26 fragment. Georg Thieme Verlag Stuttgart.
Liesener, Florian P.,Jannsen, Ulrike,Kalesse, Markus
p. 2590 - 2602
(2008/02/04)

Cinchona-alkaloid-based catalysts, and asymmetric alcoholysis of cyclic anhydrides using them
One aspect of the present invention relates to cinchona-alkaloid-based catalysts. A second aspect of the invention relates to a method of preparing a derivatized cinchona alkaloid catalyst by reacting a cinchona-alkaloid with base and a compound that has a suitable leaving group. Another aspect of the present invention relates to a method of preparing a chiral, non-racemic compound from a prochiral cyclic anhydride or a meso cyclic anhydride, comprising the step of: reacting a prochiral cyclic anhydride or a meso cyclic anhydride with a nucleophile in the presence of a catalyst; wherein said prochiral cyclic anhydride or meso cyclic anhydride comprises an internal plane of symmetry or point of symmetry or both; thereby producing a chiral, non-racemic compound; wherein said catalyst is a derivatized cinchona-alkaloid. Yet another aspect of the present invention relates to a method of kinetic resolution, comprising the step of: reacting a racemic cyclic anhydride with an alcohol in the presence of a derivatized cinchona-alkaloid catalyst.
-
Page/Page column 26

(2008/06/13)

Catalytic asymmetric desymmetrization of prochiral and meso compounds
The present invention relates to methods for the synthesis of chiral non-racemic products, e.g., enantiomerically-enriched hemiesters, from prochiral and meso starting materials, e.g., prochiral and meso cyclic anhydrides. The present invention also relates to catalysts for the aforementioned methods, and methods for synthesizing these catalysts.
-
Figure 10

(2008/06/13)

Desymmetrization of dimethyl 3-substituted glutarates through enzymatic ammonolysis and aminolysis reactions
The desymmetrization of differently 3-substituted glutarates through enzymatic aminolysis and ammonolysis has been studied. The effect of the diester and nucleophile structures, the enzymatic preparation as well as the reaction conditions have been compared in terms of both the chemical yield and enantiomeric excess of the corresponding monoamide products.
Lopez-Garcia, Monica,Alfonso, Ignacio,Gotor, Vicente
p. 603 - 609
(2007/10/03)

A highly enantioselective catalytic desymmetrization of cyclic anhydrides with modified cinchona alkaloids [3]
-
Chen, Yonggang,Tian, Shi-Kai,Deng, Li
p. 9542 - 9543
(2007/10/03)

Practical synthesis of chiral synthons for the preparation of HMG-CoA reductase inhibitors
A practical procedure for the enantioselective preparation of optically pure (R)- and (S)-monomethyl esters of 3-[(tert-butyldimethylsilyl)oxy]pentanedioic acid has been developed by diastereoselective ring-opening of 3-[(tert-butyldimethylsilyl)oxy]pentanedioic anhydride 5 by benzyl (R)- and (S)-mandelate, respectively. These half-esters afforded chiral Wittig reagent 2 and Horner-Wadsworth-Emmons (HWE) reagent 1 efficiently which have been proved to be useful in the synthesis of HMG-CoA reductase inhibitors. The method is applied to the synthesis of the (R)-3-methylglutaric acid, monomethyl ester.
Konoike,Araki
p. 7849 - 7854
(2007/10/02)

Prochiral Recognition in the Reaction of 3-Substituted Glutaric Anhydrides with Chiral Secondary Alcohols
The scope of a previously-reported process for the desymmetrization 3-substituted glutaric anhydrides has been investigated.Thus, prochiral anhydrides 5-9 react with 1-(1'-naphthyl)ethanol (2) to give glutaric acid half-esters, which are esterified by treatment with diazomethane to obtaine the corresponding diesters 16-20.The degree of prochiral recognition is inversely related to the steric bulk of the stereodifferentiating group, which the series TBDMSO, Me, Et, Ph, i-Pr, and t-Bu giving ratios of 40:1, 16:1, 14:1, 8:1, 7:1, and 1:3, respectively.The absolute sense of the prochiral recognition was established by conversion of two of the diesters, 16a and 18a, into 3-substituted valerolactones (22a, 22c) of known absolute configuration.
Theisen, Peter D.,Heathcock, Clayton H.
p. 142 - 146
(2007/10/02)

CHEMOENZYMATIC SYNTHESIS OF (R)- AND (S)-4-AMINO-3-METHYLBUTANOIC ACIDS
(R)- and (S)-4-Amino-3-methylbutanoic acids were synthesized in high yields via initial enantioselective hydrolysis of dimethyl 3-methylglutarate to methyl (R)-3-methylglutarate with pig liver esterase.The ester group was converted to an amine to give (R)-4-amino-3-methylbutanoic acid; the carboxylic acid was converted to an amine to give (S)-4-amino-3-methylbutanoic acid.
Andruszkiewicz, Ryszard,Barret, Anthony G. M.,Silverman, Richard B.
p. 159 - 166
(2007/10/02)

Synthetic studies on arene-olefin cycloadditions. 11. Total synthesis of (-)-retigeranic acid
A convergent synthesis of (-)-retigeranic acid is described which is based on a Diels-Alder and arene-alkene cycloaddition strategy.
Wender,Singh
p. 2517 - 2520
(2007/10/02)

Asymmetric Synthesis of Optically Active Lactones from Cyclic Acid Anhydrides Using Lipase in Organic Solvents
Under heterogeneous conditions, a lipase (Amano P) catalyzed the asymmetric ring opening of 3-substituted glutaric anhydrides with 1-butanol in diisopropyl ether to afford the R mono esters, which were converted to the 3-substituted δ-lactones having 60-93percent e.e.This process offered a practical means for preparing optically active 3-methyl-δ-valerolactone(93percente.e.) which is a useful chiral building block.The enzyme hydrolyzed the corresponding dimethyl esters to give the S mono esters in an aqueous medium.In both reactions, the pro R carbonyl group was preferentially attacked to yield pairs of enantiomers.
Yamamoto, Yukio,Yamamoto, Kazuyoshi,Nishioka, Takaaki,Oda, Jun'ichi
p. 3087 - 3092
(2007/10/02)

CONVENIENT SYNTHETIC ROUTE TO (+)-FARANAL AND (+)-13-NORFARANAL; THE TRAIL PHEROMONE OF PHARAOH'S ANT AND ITS CONGENER
(+)-Faranal 1a, the trail pheromone of Pharaoh's ant, and its congener, (+)-13-norfaranal 1b were synthetized from chiral building block 4 employing diastereoselective carbon-carbon bond formation.The application of crude pig liver esterase enzyme for the
Poppe, Laszlo,Novak, Lajos,Kolonits, Pal,Bata, Arpad,Szantay, Csaba
p. 1477 - 1488
(2007/10/02)

SYNTHESES WITH SULFONES XLIX: STEREO- AND ENANTIOSELECTIVE SYNTHESIS OF (S)-(-)-3,9-DIMETHYL 6-(1-METHYLETHYL) (E)-5,8-DECADIEN 1-OL ACETATE, SEXUAL PHEROMONE OF YELLOW SCALE
The stereo- and enantioselective synthesis of the yellow scale pheromone,(S)-(-)-3,9-dimethyl 6-(1-methylethyl) (E)-5,8-decadien 1-ol acetate, from 3-(R)-(+)-valerolactone 5 and benzene 8 is described.The key step is the in
Alvarez, E.,Cuvigny, C.,Herve du Penhoat, C.,Julia, M.
p. 119 - 126
(2007/10/02)

Peptide immunostimulants
Peptide compounds of formula 1, pharmaceutically acceptable base salts thereof, pharmaceutical compositions and their use as antiinfective agents where R1 is alkyl, cycloalkyl or cycloalkylmethyl; R2 is hydrogen or alkyl and R3 is hydroxy or an amino acid residue of the formula where X is hydrogen, alkyl or hydroxymethyl and nis an integer of 0 to 4 and R4 and R5 are alkyl, hydrogen, benzyl or cyclohexylmethyl.
-
(2008/06/13)

Enzymes in Organic Synthesis. 35. Stereoselective Pig Liver Esterase Catalyzed Hydrolyses of 3-Substituted Glutarate Diesters. Optimization of Enantiomeric Excess via Reaction Conditions Control
Pig liver esterase catalyzed hydrolyses of C-3-substituted dimethyl glutarates are enantiotopically selective, giving acid ester products of 17-79percent ee under normal (aqueous, pH 7, 20 deg C) hydrolysis conditions.The stereoselectivity can be increased by optimizing the reaction conditions.For example, in 20percent aqueous methanol of pH 7 at -10 deg C hydrolysis of the 3-methyl diester gives the 3-methyl acid ester of 97percent ee.The hydrolysis is pro-S selective for the diesters with small C-3 substituents and reverses to pro-R preference when C-3 is large.An active site model consistent with these data is presented.
Lam, Lister K. P.,Hui, Raymond A. H. F.,Jones, J. Bryan
p. 2047 - 2050
(2007/10/02)

ASYMMETRIC MICHAEL ADDITIONS OF ESTER ENOLATES TO ENANTIOMERICALLY PURE VINYLIC SULFOXIDES SYNTHESIS OF 3-SUBSTITUTED GLUTARATE ESTERS IN HIGH ENANTIOMERIC PURITY
Various ester enolate ions add as Michael donors to enantiomerically pure Michael acceptor cycloalkenone sulfoxides 1a and 1b and unsaturated lactone sulfoxides 3a and 3b.The level of asymmetric induction in some cases is extraordinarily high (>=95percent
Posner, Gary H.,Weitzberg, Moshe,Hamill, Terence G.,Asirvatham, Edward,Cun-heng, He,Clardy, John
p. 2919 - 2929
(2007/10/02)

SYNTHESIS OF THE TWO ENANTIOMERS OF THE SEX PHEROMONE OF DIABROTICA UNDECIMPUNCTATA HOWARDI AND OF CHIRAL PRECURSORS OF OTHER PHEROMONES STARTING FROM ENENTIOMERICALLY PURE METHYL HYDROGEN (R)-3-METHYLGLUTARATE
Readily available methyl hydrogen (R)-3-methylglutarate (2) is a useful chiral building block for the synthesis of several biologically active compounds.Enantiomerically pure (R)-2 has been employed to synthesize stereospecifically each of the two enantiomers, 1a and 1b, of 10-methyl-2-tridecanone,the sex pheromone of the southern corn rootworm, Diabrotica undecimpunctata howardi Barber.Compound (R)-2 has been also used to prepare 99percent optically pure (R)-3-methyl-1-pentanol (6) and enantiomerically pure (R)-5-methyl-i-tricosyne (7).These compounds are useful building blocks suitable for the further elaboration to other chiral insect pheromones.
Rossi, Renzo,Carpita, Adriano,Chini, Marco
p. 627 - 634
(2007/10/02)

BIFUNCTIONAL CHIRAL SYNTHONS VIA BIOCHEMICAL METHODS. VI. C5 ISOPRENOID UNITS.
Two methods for the preparation of the isoprenoid chiron 4 have been developed using a microbial kinetic resolution of 5 and an enantiotopically selective hydrolysis of 7 catalyzed by PLE.
VanMiddlesworth, Frank,Wang, Yi Fong,Zhou, Bing-nan,DiTullio, Dennis,Sih, C. J.
p. 961 - 964
(2007/10/02)

Preparations of Chiral δ-Lactones via Enantiotopically Specific Pig Liver Esterase-catalysed Hydrolyses of 3-Substituted Glutaric Acid Diesters
Pig liver esterase-catalysed hydrolyses of 3-monosubstituted glutaric acid diesters are pro-S enantiotopically specific for a broad range of C-3 substituents and permit either enantiomer of the corresponding 3-substituted valerolactones of 100percent e.e.
Francis, Christopher J.,Jones, J. Bryan
p. 579 - 580
(2007/10/02)

A Study of Stereoselective Hydrolysis of Symmetrical Diesters with Pig Liver Esterase
Pig liver esterase (PLE) catalyzed hydrolysis of dimethyl esters of symmetrical dicarboxylic acids, including meso-diacids, cis-1,2-cycloalkanedicarboxylic acids, and diacids with a prochiral center, was studied with 14 substrates.The products of these stereoselective hydrolyses are chiral monoesters of dicarboxylic acids, with an enantiomeric excess (e.e.) from 10percent to 100percent.Some of these optically active monoesters are valuable synthons in natural products synthesis.An additivity pattern of α- and β-substituents with the glutaric esters on the stereoselectivity of enzymatic hydrolysis was observed.Analysis of the experimental results leads to a model of enzyme stereoselectivity of diester hydrolysis in which the substitution pattern at α- and β-C-atoms is found to determine the absolute configuration of the resulting monoester.
Mohr, Peter,Waespe-Sarcevic, Nada,Tamm, Christoph,Gawronska, Krystyna,Gawronsky, Jacek K.
p. 2501 - 2511
(2007/10/02)