- Synthesis and properties of novel poly(hexyl-substituted lactides) for pharmaceutical applications
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Monohexyl-substituted lactide (mHLA) was synthesized by reaction of 2-hydroxyoctanoic acid with 2-bromopropionyl bromide, and polymerized with tin(II) 2-ethylhexanoate (Sn(Oct)2) or 4-dimethylaminopyridine (DMAP) in the presence of benzyl alcohol by ring-opening polymerization (ROP). Poly(monohexyl-substituted lactide) (Pm-HLA) of predictable molecular weights and narrow polydispersities were obtained in convenient bulk conditions at 100°C within short polymerization times. The polymerizations were well controlled, showing a 'living' character for targeted degrees of polymerization up to DP = 60 as evidenced by molecular weight versus conversion studies and 1H NMR end group analysis. The hexyl groups have a strong impact on the glass transition temperature (Tg), which is low for PmHLA compared to standard poly(D,L-lactide) (PLA). Tg and zero shear viscosities at 25°C can be controlled by the polymer molecular weight, ranging from -22°C for Mn = 2800 g/mol to -10°C for M n = 9100 g/mol and 140 to 4850 Pa.s, respectively. These data are in correspondence with the Fox and Flory equations. The degradation mechanism of the PmHLA polymer in phosphate buffer pH 7.4 at 37°C was shown to be similar to that of the standard PLA ('bulk erosion' type), with a slightly higher degradation rate, leading to the non-toxic degradation products lactic acid and 2-hydroxyoctanoic acid. PmHLA has the great potential as an alternative to conventional PLA/PLGA for drug delivery systems. By the hexyl-substitution the biodegradable PLA-ester backbone is conserved but the hydrophobicity is increased in comparison to standard PLA, while a viscous polymer is obtained. This leads to advantageous injectable solvent-free drug delivery systems, in which drugs can easily be incorporated by simple mixing. Schweizerische Chemische Gesellschaft.
- Trimaille, Thomas,Gurny, Robert,Moeller, Michael
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Read Online
- P450Jα: A New, Robust and α-Selective Fatty Acid Hydroxylase Displaying Unexpected 1-Alkene Formation
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Oxyfunctionalization of fatty acids (FAs) is a key step in the design of novel synthetic pathways for biobased/biodegradable polymers, surfactants and fuels. Here, we show the isolation and characterization of a robust FA α-hydroxylase (P450Jα) which catalyses the selective conversion of a broad range of FAs (C6:0-C16:0) and oleic acid (C18:1) with H2O2 as oxidant. Under optimized reaction conditions P450Jα yields α-hydroxy acids all with >95 % regioselectivity, high specific activity (up to 15.2 U mg?1) and efficient coupling of oxidant to product (up to 85 %). Lauric acid (C12:0) turned out to be an excellent substrate with respect to productivity (TON=394 min?1). On preparative scale, conversion of C12:0 reached 83 % (0.9 g L?1) when supplementing H2O2 in fed-batch mode. Under similar conditions P450Jα allowed further the first biocatalytic α-hydroxylation of oleic acid (88 % conversion on 100 mL scale) at high selectivity and in good yields (1.1 g L?1; 79 % isolated yield). Unexpectedly, P450Jα displayed also 1-alkene formation from shorter chain FAs (≤C10:0) showing that oxidative decarboxylation is more widely distributed across this enzyme family than reported previously.
- Armbruster, Julia,Steinmassl, Mathilde,Müller Bogotá, Christina A.,Berg, Gabriele,Nidetzky, Bernd,Dennig, Alexander
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p. 15910 - 15921
(2020/10/29)
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- Method for producing aliphatic carboxylic acid compound and pyridine compound adduct of aliphatic ketone compound
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Provided are: a method for producing an aliphatic carboxylic acid compound safely and easily from a starting material that can be obtained or produced industrially without generating a harmful substance such as haloform; and a pyridine compound adduct of an aliphatic ketone compound. The method for producing an aliphatic carboxylic acid compound is a method for producing an aliphatic carboxylic acid compound represented by Formula (I), and comprises: a first step for obtaining a pyridine compound adduct by adding a pyridine compound to an aliphatic ketone compound having an alpha-methyl groupin the presence of an oxidizing agent; and a second step of hydrolyzing the pyridine compound adduct in the presence of a base. In the Formula, R1 represents a substituted or unsubstituted linear alkyl group having 4-8 carbon atoms or a substituted or unsubstituted branched alkyl group having 4-8 carbon atoms; M represents hydrogen, a metal belonging to Group 1 or Group 2 of the periodic table, amethyl group, an ethyl group, an n-propyl group or an isopropyl group.
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Paragraph 0172; 0175-0176; 0182; 0185-0186; 0192; 0195-0196
(2020/05/02)
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- Preparative Asymmetric Synthesis of Canonical and Non-canonical α-amino Acids Through Formal Enantioselective Biocatalytic Amination of Carboxylic Acids
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Chemical and biocatalytic synthesis of non-canonical α-amino acids (ncAAs) from renewable feedstocks and using mild reaction conditions has not efficiently been solved. Here, we show the development of a three-step, scalable and modular one-pot biocascade for linear conversion of renewable fatty acids (FAs) into enantiopure l-α-amino acids. In module 1, selective α-hydroxylation of FAs is catalyzed by the P450 peroxygenase P450CLA. By using an automated H2O2 supplementation system, efficient conversion (46 to >99%; TTN>3300) of a broad range of FAs (C6:0 to C16:0) into valuable α-hydroxy acids (α-HAs; >90% α-selective) is shown on preparative scale (up to 2.3 g L?1 isolated product). In module 2, a redox-neutral hydrogen borrowing cascade (alcohol dehydrogenase/amino acid dehydrogenase) allowed further conversion of α-HAs into l-α-AAs (20 to 99%). Enantiopure l-α-AAs (e.e. >99%) including the pharma synthon l-homo-phenylalanine can be obtained at product titers of up to 2.5 g L?1. Based on renewables and excellent atom economy, this biocascade is among the shortest and greenest synthetic routes to structurally diverse and industrially relevant ncAAs. (Figure presented.).
- Dennig, Alexander,Blaschke, Fabio,Gandomkar, Somayyeh,Tassano, Erika,Nidetzky, Bernd
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supporting information
(2019/02/09)
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- Preparative Asymmetric Synthesis of Canonical and Non-canonical a-amino Acids through Formal Enantioselective Biocatalytic Amination of Carboxylic Acids
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Chemical and biocatalytic synthesis of non-canonical a-amino acids (ncAAs) from renewable feedstocks and using mild reaction conditions has not efficiently been solved. Here, we show the development of a three-step, scalable and modular one-pot biocascade for linear conversion of renewable fatty acids (FAs) into enantiopure l-a-amino acids. In module 1, selective a-hydroxylation of FAs is catalyzed by the P450 peroxygenase P450CLA. By using an automated H2O2 supplementation system, efficient conversion (46 to >99%; TTN>3300) of a broad range of FAs (C6:0 to C16:0) into valuable a-hydroxy acids (a-HAs; >90% a-selective) is shown on preparative scale (up to 2.3 gL1 isolated product). In module 2, a redox-neutral hydrogen borrowing cascade (alcohol dehydrogenase/amino acid dehydrogenase) allowed further conversion of a-HAs into l-a-AAs (20 to 99%). Enantiopure l-a-AAs (e.e. >99%) including the pharma synthon l-homo-phenylalanine can be obtained at product titers of up to 2.5 gL1. Based on renewables and excellent atom economy, this biocascade is among the shortest and greenest synthetic routes to structurally diverse and industrially relevant ncAAs.
- Dennig, Alexander,Blaschke, Fabio,Gandomkar, Somayyeh,Tassano, Erika,Nidetzky, Bernd
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supporting information
p. 1348 - 1358
(2019/10/28)
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- 2 - hydroxyalkyl acids prepared from a polymer composition comprising
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PROBLEM TO BE SOLVED: To provide compositions comprising polymers prepared by melt polycondensation of 2-hydroxyalkyl acids, in particular pharmaceutical compositions, and methods of preparing the compositions.SOLUTION: The composition comprises a releasable chemical substance, and one or more polymer of one or more substituted or unsubstituted C-C2-hydroxyalkyl acid, the polymer prepared by melt polycondensation.
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Paragraph 0026
(2017/07/11)
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- Compositions comprising polymers prepared from 2-hydroxyalkyl acids
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Described herein are compositions comprising polymers prepared by melt polycondensation of 2-hydroxyalkyl acids. Methods of making and using the compositions are also disclosed.
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Page/Page column 17
(2017/02/28)
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- 2-Bromo-6-isocyanopyridine as a Universal Convertible Isocyanide for Multicomponent Chemistry
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The development of 2-isocyanopyridines as novel convertible isocyanides for multicomponent chemistry is reported. Comparison of 12 representatives of this class revealed 2-bromo-6-isocyanopyridine as the optimal reagent in terms of stability and synthetic efficiency. It combines sufficient nucleophilicity with good leaving group capacity of the resulting amide moiety under both basic and acidic conditions. To demonstrate the practical utility of this reagent, an efficient two-step synthesis of the potent opioid carfentanil is presented.
- Van Der Heijden, Gydo,Jong,Ruijter, Eelco,Orru, Romano V. A.
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supporting information
p. 984 - 987
(2016/03/15)
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- A chemoselective oxidation of monosubstituted ethylene glycol: Facile synthesis of optically active α-hydroxy acids
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A mild and efficient method for the synthesis of optically active α-hydroxy acids through chemoselective oxidation of monosubstituted ethylene glycols using the TEMPO-NaOCl reagent system is described. It is evident from our studies that the solvent, pH and reaction temperature are very crucial for the success of this oxidation. The versatility of this method has been demonstrated with a variety of aliphatic, aromatic and carbohydrate substrates bearing various functional groups. the Partner Organisations 2014.
- Chinthapally, Kiran,Baskaran, Sundarababu
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supporting information
p. 4305 - 4309
(2014/06/23)
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- COMPOSITIONS COMPRISING POLYMERS PREPARED FROM 2-HYDROXYALKYL ACIDS
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Described herein are compositions comprising polymers prepared by melt polycondensation of 2-hydroxyalkyl acids. Methods of making and using the compositions are also disclosed.
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Paragraph 0077
(2013/06/04)
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- Biocatalytic racemization of α-hydroxycarboxylic acids using a stereo-complementary pair of α-hydroxycarboxylic acid dehydrogenases
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Biocatalytic racemization of aliphatic, (aryl)aliphatic and aromatic α-hydroxycarboxylic acids was achieved via a reversible oxidation-reduction sequence using a pair of stereo-complementary Prelog- and anti-Prelog d- and l-α-hydroxyisocaproate dehydrogenases from Lactobacillus confusus DSM 20196 and Lactobacillus paracasei DSM 20008, resp., overexpressed in Escherichia coli. The mild reaction conditions ensured essential 'clean' isomerization, undesired 'over-oxidation' of the substrate forming the α-ketoacid could be suppressed by exclusion of O2 and adjustment of the NAD+/NADH-ratio.
- Bodlenner, Anne,Glueck, Silvia M.,Nestl, Bettina M.,Gruber, Christian C.,Baudendistel, Nina,Hauer, Bernhard,Kroutil, Wolfgang,Faber, Kurt
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experimental part
p. 7752 - 7755
(2009/12/04)
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- Decomposition of sodium trichloroacetate in the presence of quaternary ammonium under microwave irradiation: A convenient one-pot synthesis of α-hydroxy acids in water
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A good yielding phase-transfer-catalyzed procedure for one-pot preparation of α-hydroxy acids from carbonyl compounds and sodium trichloroacetate by in situ addition and hydrolysis under microwave irradiation is described. Decomposition of sodium trichloroacetate is strongly accelerated by the presence of quaternary ammonium. The reaction can be conducted in water. Copyright Taylor & Francis Group, LLC.
- Yu, Haitao,Fang, Yun,Xia, Yongmei,Wu, Jing
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p. 2421 - 2426
(2007/10/03)
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- Personal care compositions comprising solid particles enterapped in a gel network
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The present invention relates to a personal care composition comprising a three dimensional gel polymeric network comprising: a. a polymer; b. one or more solid particles that are entrapped within said polymer during polymerization of said polymer; and c. a solvent in which said polymer is dispersed. Another embodiment further includes at least one second colorant that is substantially similar to an at least one first colorant which is a solid particle and wherein said second colorant is dispersed within said composition but is not entrapped in said polymer and is separate and distinct from said network. In contrast, a third embodiment allows for the at least one second colorant to be substantially different from the at least one first colorant.
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- Method and product for skin lightening
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A method and cosmetic product for lightening skin is provided, the method including wiping the skin with a cosmetic towelette. Impregnated on the towelette is an alpha-hydroxy carboxylic acid or salt thereof and a sunscreen agent.
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- COSMETIC COMPOSITIONS CONTAINING A SILOXANE ELASTOMER
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A skin treatment composition is provided which includes a crosslinked non-emulsifying siloxane elastomer, a volatile siloxane and at least 50% by weight of water. Inclusion of the elastomer provides a unique liquid/powdery feel when rubbed into the skin.
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- Cosmetic compositions
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The present invention relates to pigmented emulsion cosmetic compositions containing emulsifying silicone elastomers that provide a natural appearance to the skin upon application. In particular, these cosmetic compositions are formulated such that agglomeration of the pigment upon application to the skin is minimized.
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- Cosmetic compositions
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A skin treatment composition is provided which includes a crosslinked siloxane elastomer gel of specific yield point, a skin-conditioning agent, a volatile siloxane and water. Inclusions of the select elastomers provide improved uniform distribution of the pigments.
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- Anhydrous cosmetic compositions
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An anhydrous skin treatment composition is provided which includes a crosslinked emulsifying siloxane elastomer, at least 20% humectant and a volatile siloxane. Inclusion of the elastomer provides a non-traditional smooth/silky feel to the skin upon application with a non-draggy rub in.
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- Cosmetic compositions
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The invention relates to cosmetic compositions comprising a combination of non-emulsifying and emulsifying crosslinked siloxane elastomers.
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- Anhydrous cosmetic compositions
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An anhydrous skin treatment composition is provided which includes a crosslinked siloxane elastomer gel of specific yield point, a skin conditioning agent and a volatile siloxane. Inclusions of the select elastomers provide improved uniform distribution of the pigments.
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- Cosmetic compositions
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The invention relates to cosmetic compositions comprising a combination of non-emulsifying and emulsifying crosslinked siloxane elastomers.
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- Towelette product
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A disposable towelette product is provided which includes a flexible water-insoluble substrate such as a tissue impregnated with an alpha- or beta-hydroxycarboxylic acid in a cosmetically acceptable carrier vehicle. Impregnated cosmetic composition in water will have a pH no higher than 6.8. A silicone microemulsion is present to minimize any stickiness resulting from deposition of the hydroxycarboxylic acid by the towelette onto the skin. In the presence of fatty acid group containing surfactants, the silicone microemulsion controls foul odors that the surfactants may emit through hydrolysis at low pH.
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- Role of the hydrophobic moiety of tumor promoters. Synthesis and activity of 2-alkylated benzolactams
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The size and position of a hydrophobic moiety on a benzolactam skeleton, which reproduces the active conformation and biological activity of teleocidins, play an important role in the appearance of the activity. Compounds with alkyl groups of various sizes and shapes at the 2-position of benzolactam were synthesized. Structure-activity results indicate that a hydrophobic substituent at the C-2 position plays a critical role in the appearance of biological activities, as in the case of substitution at C-9.
- Endo, Yasuyuki,Yokoyama, Akihiro
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- Powdered cosmetic compositions containing silicone elastomers
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A cosmetic powder is provided which includes a crosslinked non-emulsifying siloxane elastomer, a powdered inorganic material and a skin treatment agent. Inclusion of the elastomer allows for the coupling of water as well as water soluble salts into the cosmetic powder.
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- SHORT CHAIN 2-HYDROXYCARBOXYLIC ACID-BASED DERIVATIVES OF CERAMIDES
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The present invention relates to active ceramide derivatives. Specifically, the invention relates to 2(alpha)-hydroxycarboxylic acid-based ceramide derivatives. The present invention describes a method for obtaining these compounds. The invention also relates to the use of these compounds in cosmetic compositions.
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- Compositions and methods for enhancing the topical effects of sunscreen agents
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Uses of topical compositions comprising a 2-hydroxycarboxylic acid or related compound to alleviate or improve signs of skin, nail and hair changes associated with intrinsic or extrinsic aging are disclosed. 2-Hydroxycarboxylic acids and their related compounds include, for example, 2-hydroxyethanoic acid, 2-hydroxypropanoic acid, 2-methyl 2-hydroxypropanoic acid, 2-phenyl 2-hydroxyethanoic acid, 2-phenyl 2-methyl 2-hydroxyethanoic acid, 2-phenyl 3-hydroxypropanoic acid, 2,2-diphenyl 2-hydroxyethanoic acid, 2-hydroxybutane-1,4-dioicacid, 2,3-hihydroxybutane-1,4-dioic acid, 2-carboxy 2-hydroxypentane-1,5-dioic acid, 2-ketopropanoic acid, methyl 2-ketopropanoate, ethyl 2-ketopropanoate, and gluconolactone. Topical application of compositions comprising 2-hydroxycarboxylic acid and/or related compounds has been found to alleviate or improve skin lines; blotches; blemishes; nodules; wrinkles; pigmented spots; atrophy; precancerous lesions; elastotic changes characterized by leathery, coarse, rough, dry and yellowish skin; and other skin changes associated with intrinsic aging or skin damages caused by extrinsic factors such as sunlight, radiations, air pollution, wind, cold, dampness, heat, chemicals, smoke and cigarette smoking. Topical applications of such compositions have also been found to improve the overall qualities of nail and hair affected by intrinsic aging or damaged by extrinsic factors.
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- Samarium diiodide-promoted diiodomethylation of carbonyl compounds with iodoform. Synthetic applications of diiodoalcohols
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A rapid and effective diiodomethylation of carbonyl compounds using SmI2 and iodoform is described. Transformations of the obtained diiodoalcohols 2 into α-iodoaldehydes 5 and α-hydroxyacids 6 is also reported.
- Concellon, Jose M.,Bernad, Pablo L.,Perez-Andres, Juan A.
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p. 1409 - 1412
(2007/10/03)
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- Anhydrous cosmetic compositions
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A skin treatment composition is provided which includes a crosslinked non-emulsifying siloxane elastomer, a skin conditioning agent, a volatile siloxane and no more than 5% water. Hydrocarbons such as petrolatum and polyols such as glycerin are the preferred skin conditioning agents. Inclusion of the elastomer provides a non-traditional smooth/silky feel to the skin upon application with a non-draggy rub in.
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- Anhydrous cosmetic composition with ceramides for firming skin
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A method and cosmetic composition for improving skin firmness are provided through an anhydrous composition including a hydrophobic carrier which may be a silicone or hydrocarbon for delivering an effective amount of a ceramide formed of a sphingoid base linked through an amide to a 2-hydroxycarboxylic C2-C30group.
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- Cosmetic compositions for reducing or preventing signs of cellulite
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The invention is directed to increasing the strength and firmness of the skin and reducing the signs of cellulite. The inventive method includes applying to the skin a composition that includes inositol phosphate, particularly phytic acid and its salts, in a cosmetically acceptable carrier.
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- Effects of Gln102Arg and Cys97Gly mutations on the structural specificity and stereospecificity of the L-lactate dehydrogenase from Bacillus stearothermophilus
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The L-lactate dehydrogenase of Bacillus stearothermophilus (BSLDH) is a thermostable enzyme with considerable potential for applications in asymmetric synthesis. An understanding of the factors controlling its structural specificity and stereospecificity is therefore of interest. In this paper the effects of Gln102 → Arg and Cys97 → Gly mutations have been evaluated. In a survey of thirteen 2-keto acids, the Q102R mutation was found to reduce the activity of BSLDH toward the reduction of RCOCOOH substrates with small or hydrophilic R groups without affecting its activity toward those with larger, hydrophobic R substituents. In addition, the mutants have a high affinity for C3- and C4-2-keto dicarboxylates. The extent of fructose 1,6-diphosphate activation of the mutant enzymes was similar to its effect on wild-type BSLDH. The mutants also retained the synthetically desirable thermostability. As a probe of the commitment of BSLDH to L stereospecificity, the Q102R mutation was introduced to allow the new 102R site to compete with Arg171 for binding of the COO- groups of the RCOCOOH substrates, which would reverse the normal RCOCOOH orientation at the active site and thereby open up the possibility of the formation of a D-2-hydroxy acid in place of the natural L product. However, L stereospecificity in 2-keto acid reduction was strictly retained by the Q102R mutants. This was confirmed by preparative-scale reductions of pyruvate and phenylpyruvate to give the corresponding L-hydroxy acids in enantiomerically pure form and by comparison of the kinetics of oxidation of L- and D-lactate and L- and D-phenyl lactate. No evidence for substrate activity for the D enantiomers of either of these was seen with WT or mutant enzymes. Some catalysis of D-malate oxidation by both WT and mutant BSLDH was observed, but the L enantiomer was still preferred to approximately the same degree in both cases. That the inability of BSLDH and its 102R mutants to catalyze D-2-hydroxy acid oxidations was not simply due to the failure of the D enantiomers to bind at the active site was established by a comparison of competitive inhibition constants for the above L- and D-hydroxy acids. CD spectroscopy showed that the Gln102 → Arg mutations were not benign but induced significant structural perturbations. Electrostatic potential contours suggest that the structural changes are partly due to long-range interactions of the positive charge of the guanidinium group of Arg102 with several other residues that form an area of negative potential adjacent to the active site. The Cys97 → Gly mutation, while inadvertent, was of interest because of the potential specificity effects arising from its location adjacent to the hinge of the flexible 98-110 loop. However, its effects on BSLDH specificity were minor.
- Kallwass, Helmut K. W.,Luyten, Marcel A.,Parris, Wendy,Gold, Marvin,Kay, Cyril M.,Bryan Jones
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p. 4551 - 4557
(2007/10/02)
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- A convenient route for the homologation of saturated esters to α,β-unsaturated esters
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Methyl hexanoate (1a) is transformed to methyl 2-hydroxyheptanoate (5a) employing the following sequence of reactions (Scheme 1); (i) reaction with sodium hydride-dimethyl sulfoxide, (ii) Pummerer rearrangement with acetic anhydride-sodium acetate, (iii) alkaline hydrolysis and (iv) esterification with diazomethane.The α-hydroxy ester (5a) is converted into methyl 2E-heptenoate (7a) employing the following reactions (Scheme 2); (i) reaction with phosphorous tribromide and (ii) elimination using DBU.Thus, the sequence of reactions given in Schemes 1 and 2 provide aconvenient route for the one carbon homologation of saturated esters to α,β-unsaturated esters.
- Mohan, H Rama,Rao, A S
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p. 698 - 700
(2007/10/02)
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- Synthesis of S-Methyl 2-Hydrxyalkanethioates, 2-Hydroxyalkanoic Acids and Related Compounds via the Addition Reaction of Tris(methylthio)methanide Ion to Alkanals
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In connection with the studies on biological activities on myrmicacin and related compounds, the synthetic method for 2-hydroxyalkanoic acids and the corresponding 1,2-diols was studied.The addition reaction of tris(methylthio)methyllithium to the aldehydes (propanal-dodecanal) gave the corresponding 1,1,-tris(methylthio)-2-alkanols 1a-j.Treatment of 1 with mercury(II) chloride-mercury(II) oxide in water-acetone afforded S-methyl 2-hydroxyalkanethioates 2a-j, and in methanol methyl 2-hydroxyalkanoates 3c-j were obtained.Reduction of the thioates 2 with lithium aluminium hydride gave 1,2-diols 4c-j and saponification produced the corresponding 2-hydroxyalkanoic acids 5c-j.
- Orito, Kazuhiko,Seki, Yoshikatsu,Suginome, Hiroshi,Iwadare, Tsukasa
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p. 2013 - 2017
(2007/10/02)
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- An Evaluation of the Substrate Specificity, and of Its Modification by Site-Directed Mutagenesis, of the Cloned L-Lactate Dehydrogenase from Bacillus stearothermophilus
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The L-lactate dehydrogenase of Bacillus stearothermophilus (BSLDH) is a stable, thermophilic oxidoreductase.It has been selected as a model of enzymes with considerable future promise in assymetric synthesis in that it has been cloned to ensure a plentiful and inexpensive supply and because of the potential for tailoring its specificity to accept unnatural substrate structures via the site-directed mutagenesis techniques of moleculer biology.In this study, the specificity of BSLDH toward representative α-keto acids possessing straight- and branched-chain alkyl,cycloalkyl, or aromatic side chains has been evaluated.The results show that substrates that are sterically bulky in the region of the α-keto group to be reduced are poorly accepted by the enzyme.Graphics analyses indicated that the low activities of these hindered substrates might be partly due to a bad interaction of the active site residue Gln102 with large or branched substituents adjacent to the α-keto group.Accordingly, Gln102 has been replaced by the smaller Asn residue by site-directed mutagenesis in an attempt to expand the active site volume available to receive substrates larger than the natural pyruvate.However, the kinetic data show that bulky α-keto acids are only marginally better accommodated by the Gln102 -> Asn mutant than by the wild-type enzyme.
- Luyten, Marcel A.,Bur, Daniel,Wynn, Hla,Parris, Wendy,Glod, Marvin,et al.
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p. 6800 - 6804
(2007/10/02)
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- α-Amino Acids as Chiral Educts for Asymmetric Products. Chirospecific Syntheses of the 5-Butyl-2-heptylpyrrolidines from Glutamic Acid
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Both enantiomers of trans-5-butyl-2-heptylpyrrolidine, an active and major component in the repellent venom of the ant Solenopsis fugax, have been synthesized with very high diastereomeric and optical purity from glutamic acid.Both enantiomers of the cis isomer also have been synthesized in an extension of our methodology to encompass the preparation of both cis and trans, optically pure, 2,5-disubstituted pyrrolidines and because of their potential entomological interest.Initially, a sulfide contraction process efficiently introduces the first side chain onto a pyroglutamate intermediate.Various strategies to elaborate the second side chain have been developed along with methods to control and establish the relative steroechemistry at C-2 and C-5 of the pyrrolidine ring with high selectivity. 2,5-Dialkyl-1-pyrrolidines, which also have been identified in the ant venom, can be prepared by these processes as well with specific absolute stereochemistry.
- Shiosaki, Kazumi,Rapoport, Henry
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p. 1229 - 1239
(2007/10/02)
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