- IDENTIFICATION, SYNTHESIS, AND BIOACTIVITY OF A MALE-PRODUCED AGGREGATION PHEROMONE IN ASSASSIN BUG, Pristhesancus Plagipennis (HEMIPTERA: REDUVIIDAE)
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Pristhesancus plagipennis, a large Australian assassin bug, possesses three pairs abdominal glands (DSGs). In the male, the anterior and posterior glands are hypertrophied and secrete an attractant pheromone. Gas chromatography-mass spectrometry (GC-MS) analyses of male DAG extracts and airborne volatiles emitted from calling males showed the pheromone signature to be dominated by the novel component. Subsequent chemical manipulations, GC-MS, and chiral-column analyses established its identity as (Z)-3-hexenyl (R)-2-hydroxy-3-methylbutyrate. Minor components included 3-methylbutanol, 2-phenylethanol, (Z)-3-hexenol, decanal, (E)-2-hexenoic acid, and three minor hexenyl esters. Bioactivity studies using laboratory olfactometers and outdoor flight cages demonstrated attraction by female P. plagipennis to calling males, heptane extracts of male posterior DAGs and a synthetic formulation of the (Z)R enantiomer of the major ester, alone or in combination with other components of male anterior and posterior DAGs. Males were also attracted to the major ester. The racemate and S enantiomer of the ester were not attractive. Contamination of the (Z)R enantiomer with 30-60 percent of the E isomer also made the compound nonattractive. This is the first report of an aggregation pheromone in the Reduviidae. The prospects for pheromonal manipulation of P. plagipennis populations to enhance the value of this predator in horticultural ecosystems, are discussed. - Keywords: Pristhesancus plagipennis; assassian bug; Hemiptera; Reduviidae; dorsal abdominal glands; (Z)-3-hexenyl (R)-2-hydroxy-3-methylbutyrate; aggregation pheromone
- James, David G.,Moore, Christopher J.,Aldrich, Jeffrey R.
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- Cyclohexadepsipeptides from Acremonium sp. BCC 28424
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Six new cyclohexadepsipeptides, beauvenniatins A-E (1-5), and beauvericin J (6), together with the known beauvericin (7) and enniatin B (8), were isolated from the fungus Acremonium sp. BCC 28424. The productions of minor derivatives 3-6, possessing an N-
- Isaka, Masahiko,Yangchum, Arunrat,Sappan, Malipan,Suvannakad, Rapheephat,Srikitikulchai, Prasert
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- (3R,6R)-4-methyl-6-(1 -methylethyl)-3-phenylmethyl-perhydro-1,4-oxazine-2,5-dione: An apoptosis-inducer from the fruiting bodies of Isaria japonica
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(3R,6R)-4-Methyl-6-(1-methylethyl)-3-phenylmethylperhydro1,4-oxazine-2,5- dione (1) was isolated from the fruiting bodies of Isaria japonica as an apoptosis-inducing agent. The complete structural assignment of the compound was accomplished on the basis of spectroscopic methods and chemical transformations. Compound 1 induced apoptotic cell death of the human leukemia cells (HL-60) in a dose-dependent manner, ranging from 5.0 μg/ml to 100.0 μg/ml.
- Oh, Hyuncheol,Kim, Taewan,Oh, Gi-Su,Pae, Hyun-Ock,Hong, Kyung-Hwan,Chai, Kyu-Yun,Kwon, Tae-Oh,Chung, Hun-Taeg,Lee, Ho-Sub
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Read Online
- Synthetic Indolactam V Analogues as Inhibitors of PAR2-Induced Calcium Mobilization in Triple-Negative Breast Cancer Cells
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Human proteinase-activated receptor 2 (PAR2), a transmembrane G-protein-coupled receptor (GPCR), is an attractive target for a novel anticancer therapy, as it plays a critical role in cell migration and invasion. Selective PAR2 inhibitors therefore have potential as anti-metastatic drugs. Knowing that the natural product teleocidin A2 is able to inhibit PAR2 in tumor cells, the goal of the present study was to elaborate structure–activity relationships and to identify potent PAR2 inhibitors with lower activity against the adverse target, protein kinase C (PKC). For this purpose, an efficient gram-scale total synthesis of indolactam V (i.e., the parent structure of all teleocidins) was developed, and a library of derivatives was prepared. Some compounds were indeed found to exhibit high potency as PAR2 inhibitors at low nanomolar concentrations with improved selectivity (relative to teleocidin A2). The pseudopeptidic fragment bridging the C3 and C4 positions of the indole core proved to be essential for target binding, whereas activity and target selectivity depends on the substituents at N1 or C7. This study revealed novel derivatives that show high efficacy in PAR2 antagonism combined with increased selectivity.
- Stein, Jan,Stahn, Sonja,Neud?rfl, J?rg-M.,Sperlich, Julia,Schmalz, Hans-Günther,Teusch, Nicole
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supporting information
p. 147 - 154
(2018/02/06)
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- Synthesis of Natural and Unnatural Cyclooligomeric Depsipeptides Enabled by Flow Chemistry
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Flow chemistry has been successfully integrated into the synthesis of a series of cyclooligomeric depsipeptides of three different ring sizes including the natural products beauvericin (1 a), bassianolide (2 b) and enniatin C (1 b). A reliable flow chemistry protocol was established for the coupling and macrocyclisation to form challenging N-methylated amides. This flexible approach has allowed the rapid synthesis of both natural and unnatural depsipeptides in high yields, enabling further exploration of their promising biological activity. Harnessing technology: Flow chemistry has been successfully integrated into the synthesis of a series of cyclooligomeric depsipeptides of three different ring sizes including the natural products beauvericin (1 a), bassianolide (2 b) and enniatin C (1 b), resulting in increased overall yields, while decreasing the effort required for the researcher.
- Lücke, Daniel,Dalton, Toryn,Ley, Steven V.,Wilson, Zoe E.
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supporting information
p. 4206 - 4217
(2016/03/16)
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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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- Urumamide, a novel chymotrypsin inhibitor with a β-amino acid from a marine cyanobacterium Okeania sp.
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Urumamide, a novel cyclic depsipeptide that contains a β-amino acid, was isolated from a marine cyanobacterium Okeania sp. Its gross structure was determined by spectroscopic analyses, and the absolute configuration was established based on Marfey's analyses and chiral HPLC analyses of hydrolysis products. Biologically, urumamide inhibited the growth of human cancer cells. In addition, urumamide inhibited chymotrypsin.
- Kanamori, Yuki,Iwasaki, Arihiro,Sumimoto, Shinpei,Suenaga, Kiyotake
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supporting information
p. 4213 - 4216
(2016/08/25)
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- PHENOXYETHOXY COMPOUNDS
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The present invention provides a compound of the Formula I: or a pharmaceutically acceptable salt thereof.
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Paragraph 0025-0028
(2014/09/03)
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- Solid-phase synthesis of tetrahydropyridazinedione-constrained peptides
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The design and solid-phase synthesis of tetrahydropyridazine-3,6-dione (Tpd) peptidomimetics derived from backbone-aminated peptides is reported. The described protocol features the synthesis of chiral α-hydrazino acids suitable for chemoselective incorporation into growing peptide chains. Acid-catalyzed cyclization to form the Tpd ring during cleavage affords the target peptidomimetics in good yield and purity. The scope of Tpd incorporation is demonstrated through the synthesis of constrained peptides featuring nucleophilic/electrophilic side chains and sterically encumbered α-substituted hydrazino acid residues. (Chemical Equation Presented).
- Kang, Chang Won,Ranatunga, Sujeewa,Sarnowski, Matthew P.,Del Valle, Juan R.
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supporting information
p. 5434 - 5437
(2015/02/19)
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- Chiral propargylic cations as intermediates in SN1-type reactions: Substitution pattern, nuclear magnetic resonance studies, and origin of the diastereoselectivity
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Nine propargylic acetates, bearing a stereogenic center (-C*HXR 2) adjacent to the electrophilic carbon atom, were prepared and subjected to SN1-type substitution reactions with various silyl nucleophiles employing bismuth trifluoromethanesulfonate [Bi(OTf)3] as the Lewis acid. The diastereoselectivity of the reactions was high when the alkyl group R2 was tertiary (tert-butyl), irrespective of the substituent X. Products were formed consistently with a diastereomeric ratio larger than 95:5 in favor of the anti-diastereoisomer. If the alkyl substitutent R2 was secondary, the diastereoselectivity decreased to 80:20. The reaction was shown to proceed stereoconvergently, and the relative product configuration was elucidated. The reaction outcome is explained by invoking a chiral propargylic cation as an intermediate, which is preferentially attacked by the nucleophile from one of its two diastereotopic faces. Density functional theory (DFT) calculations suggest a preferred conformation in which the group R2 is almost perpendicular to the plane defined by the three substituents at the cationic center, with the nucleophile approaching the electrophilic center opposite to R2. Transition states calculated for the reaction of allyltrimethylsilane with two representative cations support this hypothesis. Tertiary propargylic cations with a stereogenic center (-C* HXR2) in the α position were generated by ionization of the respective alcohol precursors with FSO3H in SO2ClF at -80 C. Nuclear magnetic resonance (NMR) spectra were obtained for five cations, and the chemical shifts could be unambiguously assigned. The preferred conformation of the cations as extracted from nuclear Overhauser experiments is in line with the preferred conformation responsible for the reaction of the secondary propargylic cations.
- Nitsch, Dominik,Huber, Stefan M.,Poethig, Alexander,Narayanan, Arjun,Olah, George A.,Prakash, G. K. Surya,Bach, Thorsten
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supporting information
p. 2851 - 2857
(2014/03/21)
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- Structural revision and absolute configuration of lateritin
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'Lateritin' (1), a morpholine-2,5-dione (depsipeptide), was reinvestigated for its structure and absolute configuration. On the basis of thorough 1D and 2D NMR and mass spectrometrical analyses, the structure of 1 was revised to be identical with beauvericin (8) and confirmed that beauvericin (8) is the trimeric lactone of 'lateritin' (1). The absolute configuration was determined by acidic hydrolysis, followed by application of Marfey's method, menthyl ester derivatization, and GC-MS analysis. In addition, the specific optical rotation values of the hydrolysis products were compared with those of available standards.
- Ola, Antonius R.B.,Aly, Amal H.,Lin, Wenhan,Wray, Victor,Debbab, Abdessamad
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supporting information
p. 6184 - 6187
(2014/12/10)
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- Lipopeptides from the tropical marine cyanobacterium symploca sp.
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A collection of the tropical marine cyanobacterium Symploca sp., collected near Kimbe Bay, Papua New Guinea, previously yielded several new metabolites including kimbeamides A-C, kimbelactone A, and tasihalide C. Investigations into a more polar cytotoxic fraction yielded three new lipopeptides, tasiamides C-E (1-3). The planar structures were deduced by 2D NMR spectroscopy and tandem mass spectrometry, and their absolute configurations were determined by a combination of Marfeys and chiral-phase GC-MS analysis. These new metabolites are similar to several previously isolated compounds, including tasiamide (4), grassystatins (5, 6), and symplocin A, all of which were isolated from similar filamentous marine cyanobacteria.
- Mevers, Emily,Haeckl, F. P. Jake,Boudreau, Paul D.,Byrum, Tara,Dorrestein, Pieter C.,Valeriote, Frederick A.,Gerwick, William H.
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p. 969 - 975
(2014/05/20)
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- Continuous multiple liquid-liquid separation: Diazotization of amino acids in flow
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A second-generation laboratory-scale, modular liquid-liquid separation device based on computer-controlled high-pressure pumps and a high-resolution digital camera has been invented. The diazotization of amino acids to produce valuable chiral hydroxyacids is demonstrated in flow for the first time. The use of a triple-separator system in conjuction with the developed diazotization process allows the safe and efficient production and automated isolation of multigram quantities of valuable chiral hydroxyacids.
- Hu, Dennis X.,O'Brien, Matthew,Ley, Steven V.
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supporting information; experimental part
p. 4246 - 4249
(2012/10/08)
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- Synthesis, characterization and activity of new phosphonate dipeptides as potential inhibitors of VanX
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VanX, a Zn(II)-dependent D-ala-D-ala dipeptidase, is essential for vancomycin resistance in Enterococcus faecium. The enzymatic activity of VanX was previously found to be inhibited competitively by 2-{[(1-aminoethyl) (hydroxy) phosphoryl]oxy} propanoic acid (1B). Here we report the synthesis and characterization of seven phosphonate dipeptide analogs of D-ala-D-ala with various substituent, the activity evaluation indicated that six of these phosphonate analogs inhibit VanX with IC50 of 0.48-8.21 mM. These data revealed a structure-activity relationship which is that the large substituent group on β-carbon resulted in low binding affinity of the phonphonate analog to VanX. This information will be helpful to guide the design and synthesis of the tightly-binding inhibitors for VanX.
- Jia, Chao,Yang, Ke-Wu,Liu, Cheng-Cheng,Feng, Lei,Xiao, Jian-Min,Zhou, Li-Sheng,Zhang, Yi-Lin
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supporting information; experimental part
p. 482 - 484
(2012/03/11)
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- Symplocin A, a linear peptide from the bahamian cyanobacterium symploca sp. configurational analysis of N, N -dimethylamino acids by chiral-phase HPLC of naphthacyl esters
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The absolute stereostructures of the components of symplocin A (3), a new N,N-dimethyl-terminated peptide from the Bahamian cyanobacterium Symploca sp., were assigned from spectroscopic analysis, including MS, 2D NMR, and Marfey's analysis. The complete a
- Molinski, Tadeusz F.,Reynolds, Kirk A.,Morinaka, Brandon I.
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experimental part
p. 425 - 431
(2012/07/13)
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- Cyclodepsipeptides, sesquiterpenoids, and other cytotoxic metabolites from the filamentous fungus Trichothecium sp. (MSX 51320)
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Two new cyclodepsipeptides (1 and 2), two new sesquiterpenoids (3 and 4), and the known compounds guangomide A (5), roseotoxin S, and three simple trichothecenes were isolated from the cytotoxic organic extract of a terrestrial filamentous fungus, Trichothecium sp. The structures were determined using NMR spectroscopy and mass spectrometry. Absolute configurations of the cyclodepsipeptides were established by employing chiral HPLC, while the relative configurations of 3 and 4 were determined via NOESY data. The isolation of guangomide A was of particular interest, since it was reported previously from a marine-derived fungus.
- Sy-Cordero, Arlene A.,Graf, Tyler N.,Adcock, Audrey F.,Kroll, David J.,Shen, Qi,Swanson, Steven M.,Wani, Mansukh C.,Pearce, Cedric J.,Oberlies, Nicholas H.
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experimental part
p. 2137 - 2142
(2011/12/14)
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- PROTEASE INHIBITORS, COMPOSITIONS AND METHODS OF USE
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This invention relates to grassystatins A, B and C, and their isolated or purified forms. The compounds of the invention are useful as aspartic protease, gamma secretase, or metalloprotease inhibitors. Methods of using the compounds and compositions thereof are also disclosed.
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Page/Page column 33-34
(2011/01/12)
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- Grassystatins A-C from marine cyanobacteria, potent cathepsin E inhibitors that reduce antigen presentation
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In our efforts to exploremarine cyanobacteria as a source of novel bioactive compounds, we discovered a statine unit-containing linear decadepsipeptide, grassystatin A (1), which we screened against a diverse set of 59 proteases. We describe the structure
- Kwan, Jason C.,Eksioglu, Erika A.,Liu, Chen,Paul, Valerie J.,Luesch, Hendrik
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experimental part
p. 5732 - 5747
(2010/03/24)
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- Natural products chemistry and taxonomy of the marine cyanobacterium Blennothrix cantharidosmum
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A Papua New Guinea field collection of the marine cyanobacterium Blennothrix cantharidosmum was investigated for its cytotoxic constituents. Bioassay-guided isolation defined the cytotoxic components as the known compounds lyngbyastatins 1 and 3. However, six new acyl proline derivatives, tumonoic acids D-I, plus the known tumonoic acid A were also isolated. Their planar structures were defined from NMR and MS data, while their stereostructures followed from a series of chiral chromatographies, degradation sequences, and synthetic approaches. The new compounds were tested in an array of assays, but showed only modest antimalarial and inhibition of quorum sensing activities. Nevertheless, these are the first natural products to be reported from this genus, and this inspired a detailed morphologic and 16S rDNA-based phylogenetic analysis of the producing organism.
- Clark, Benjamin R.,Engene, Niclas,Teasdale, Margaret E.,Rowley, David C.,Matainaho, Teatulohi,Valeriote, Frederick A.,Gerwick, William H.
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experimental part
p. 1530 - 1537
(2009/09/06)
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- Carriebowmide, a new cyclodepsipeptide from the marine cyanobacterium Lyngbya polychroa
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The new cyclodepsipeptide carriebowmide (1), which contains two rare amino acids, 3-amino-2-methylhexanoic acid and methionine sulfoxide, was isolated from the fish-deterrent lipophilic extract of the marine cyanobacterium Lyngbya polychroa, collected from the fore reef near the Smithsonian field station at Carrie Bow Cay, Belize. Its planar structure was determined by NMR spectroscopic techniques. The absolute stereochemistry of the hydroxy acid and all α-amino acid-derived units was ascertained by chiral HPLC analysis of the acid hydrolysate. The stereochemistry of the β-amino acid moiety, 3-amino-2-methylhexanoic acid, was established by Marfey analysis of the acid hydrolysate.
- Gunasekera, Sarath P.,Ritson-Williams, Raphael,Paul, Valerie J.
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experimental part
p. 2060 - 2063
(2009/09/06)
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- A stable, convertible isonitrile as a formic acid carbanion [ -COOH] equivalent and its application in multicomponent reactions
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The application of 2-(2,2-dimethoxyethyl) phenyl isonitrile in Ugi, Passerini, and Ugi-Smiles reactions is described. The simple transformation to highly activated indolyl amides allows functional-group conversion of the isonitrile moiety into a variety of carboxylic acid derivatives, overall acting as a neutral, nucleophilic COOH equivalent. Georg Thieme Verlag Stuttgart.
- Kreye, Oliver,Westermann, Bernhard,Wessjohann, Ludger A.
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p. 3188 - 3192
(2008/09/20)
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- ALTERNATIVE SYNTHESIS OF RENIN INHIBITORS AND INTERMEDIATES THEREOF
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The present invention relates to synthetic routes to prepare a compound of the formula (A); wherein R1 is halogen, C1-6 halogenalkyl, C1-6 alkoxy-C1-6 alcoxy or C1-6alkoxy-C1-6alkyl; R2 is halogen, C1-4alkyl or C1-4alkoxy; R3 and R4 are independently branched C3-6alkyl; and R5 is cycloalkyl, C1-6alkyl, C1-6hydroxyalkyl, Cl-6alkoxy-C 1-6alkyl, C1-6alkanoyloxy-C1-6alkyl, C1-6aminoalkyl, C1-6alkylamino-C 1-6alkyl, Cl-6dialkylamino-C1-6alkyl, C1-6alkanoylamino- C1-6alkyl, HO(O)C-Cl-6alkyl, C1-6alkyl-O-(O)C-C1-6alkyl, H2N-C(O)-Cl-6alkyl, C1-6alkyl-HN-C(O)-C1-6alkyl or (C1-6alkyl)2N-C(O)-C1-6alkyl; or a pharmaceutically acceptable salt thereof as well as key intermediates obtained when following these routes as well as their preparation.
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Page/Page column 13
(2010/10/20)
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- Biocatalytic racemization of aliphatic, arylaliphatic, and aromatic α-hydroxycarboxylic acids
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Biocatalytic racemization of a range of aliphatic, (aryl)aliphatic, and aromatic α-hydroxycarboxylic acids was accomplished by using whole resting cells of a range of Lactobacillus spp. The mild (physiological) reaction conditions ensured an essentially "clean" isomerization in the absence of side reactions, such as elimination or decomposition. Whereas straight-chain aliphatic 2-hydroxy-carboxylic acids were racemized with excellent rates (up to 85% relative to lactate), steric hindrance was observed for branched-chain analogues. Good rates were observed for aryl-alkyl derivatives, such as 3-phenyllactic acid (up to 59%) and 4-phenyl-2-hydroxybutanoic acid (up to 47%). In addition, also mandelate and its o-chloro analogue were accepted at a fair rate (45%). This biocatalytic racemization represents an important tool for the deracemization of a number of pharmaceutically important building blocks.
- Glueck, Silvia M.,Pirker, Monika,Nestl, Bettina M.,Ueberbacher, Barbara T.,Larissegger-Schnell, Barbara,Csar, Katrin,Hauer, Bernhard,Stuermer, Rainer,Kroutil, Wolfgang,Faber, Kurt
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p. 4028 - 4032
(2007/10/03)
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- Synthesis of brassinosteroids of varying acyl side chains and evaluation of their brassinolide-like activity
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Brassinosteroids containing various side chain moieties were synthesized and their activity was determined as the reciprocal logarithm of the ED 50 (50% effective dose per plant in moles) in the rice lamina inclination assay using synergist indole-3-acetic acid (IAA). The introduction of a hydroxyl group in the α-position to the carbonyl group of the ester structure significantly enhanced the activity. 2α,3α-Dihydroxy- 17β-[(2R,3S)-2-hydroxy-3-methylpentanoyl]oxy-B-homo-7-oxa-5α- androstan-6-one showed the highest activity, for which the pED50 was determined to be 10.5 under synergistic conditions with IAA. Under identical conditions, the pED50 values of brassinolide and castasterone were determined to be 13.6 and 12.3 respectively. With respect to the α-carbon of the acyl moiety, the R-form was 10 times more potent than the corresponding S-form. Substituting the terminal structure (Et) of the side chain to that of the most potent compound, brassinolide (i-Pr), did not increase the activity.
- Uesusuki, Shinya,Watanabe, Bunta,Yamamoto, Shuji,Otsuki, Junko,Nakagawa, Yoshiaki,Miyagawa, Hisashi
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p. 1097 - 1105
(2007/10/03)
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- PROCESS FOR PRODUCTION OF OPTICALLY ACTIVE 2-HALOGENO- CARBOXYLIC ACIDS
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The invention provides processes for producing efficiently optically active 2-halogenocarboxylic acids useful in the preparation of drugs or the like and salts thereof with amines. Specifically, an optically active 2-halogenocarboxylic acid is produced by halogenating an optically active amino acid in water in the presence of a hydrophobic organic solvent and nitrous acid with the configuration retained and with the racemization inhibited through the removal of 2-hydroxy- bromocarboxylic acid formed as a by-product; the obtained optically active 2-halogenocarboxylic acid is transferred to an aqueous phase by converting it into a salt thereof with a base, followed by the removal of the organic phase; and the optically active 2-halogenocarboxylic acid is transferred again to an organic solvent phase, followed by the removal of the aqueous phase, whereby an optically active 2-halogenocarboxylic acid is obtained through the removal of a halogen component. Further, a high-quality salt of an optically active 2-halogenocarboxylic acid with an amine can be obtained by a crystallization method wherein the amine is added over the period of 1/2 hour or longer either continuously or in portions and/or wherein the crystallization solvent consists of a hydrophobic organic solvent and a hydrophilic organic solvent.
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- pH-Dependent Chemoselective Synthesis of α-Amino Acids. Reductive Amination of α-Keto Acids with Ammonia Catalyzed by Acid-Stable Iridium Hydride Complexes in Water
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An acid-stable hydride complex [Cp*IrIII(bpy)H]+ {1, Cp* = η5-C5Me5, bpy = 2,2′-bipyridine} serves as the active catalyst for the highly chemoselective synthesis of α-amino acids by reductive aminatio
- Ogo, Seiji,Uehara, Keiji,Abura, Tsutomu,Fukuzumi, Shunichi
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p. 3020 - 3021
(2007/10/03)
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- Synthetic methods for aplidine and new antitumoral derivatives, methods of making and using them
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The invention provides aplidine derivatives and synthetic methods.
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- Dynamic kinetic resolution via dual-function catalysis of modified cinchona alkaloids: Asymmetric synthesis of α-hydroxy carboxylic acids
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A highly enantioselective catalytic transformation of racemic α-hydroxy acids to optically active α-hydroxy acids is reported. A new procedure was developed for the condensation of racemic α-hydroxy acids with trichloromethyl chloroformate (diphosgene) at room temperature in the presence of activated charcoal to form 5-substituted-1,3-dioxolane-2,4-diones in 90-100% yield. An efficient dynamic kinetic resolution of 5-aryl dioxolanediones was realized via a modified cinchona alkaloid-catalyzed alcoholytic opening of the dioxolanedione ring, generating a variety of optically active α-hydroxy esters in 91-96% ee and 61-85% chemical yield. In this dynamic kinetic resolution, the modified cinchona alkaloid was found to serve dual catalytic roles, mediating both the rapid racemization of the 5-aryl dioxolanediones and the enantioselective alcoholytic ring opening of the 5-aryl dioxolanediones. Consequently, both enantiomers of the 5-aryl dioxolanediones were converted to highly enantiomerically enriched aromatic α-hydroxy esters in yields (61-85%), far exceeding the maximum of 50% for a normal kinetic resolution. This development not only represents an expansion of the scope of asymmetric acyl-transfer catalysis of synthetic catalysts but also provides a new approach for the development of efficient chemical dynamic kinetic resolutions promoted by a single catalyst. 5-Alkyl dioxolanediones were resolved by a conventional but highly enantioselective kinetic resolution to provide α-hydroxy acids and esters in high optical purity and good yields. Copyright
- Tang, Liang,Deng, Li
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p. 2870 - 2871
(2007/10/03)
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- Total synthesis of bafilomycin A1 relying on iterative 1,2-induction in acyclic precursors
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The macrolide bafilomycin A1 was synthesized starting from D-valine and D-mannitol as chiral progenitors of propionate units. Acyclic subunits corresponding to different parts of the molecule were constructed based on an iterative 1,2-asymmetric induction protocol as a distinctive feature of the synthesis. The assembly of two segments encompassing the entire carbon framework of the macrolide was achieved by using a Stille coupling. The resulting seco-ester was further manipulated to provide crystalline bafilomycin A1 via a conventional carbodiimide-mediated Keck-type macrolactonization.
- Hanessian,Ma,Wang
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p. 10200 - 10206
(2007/10/03)
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- New cyclic depsipeptide antibiotics, clavariopsins A and B, produced by an aquatic hyphomycetes, Clavariopsis aquatica: 2. Structure analysis
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The structures of new cyclic decadepsipeptides, clavariopsins A and B, were determined to be cyclo[-(R)-2-hydroxyisovaleryl-L-pipecolyl-L-MeVal- L-Val-L-MeAsp-L-Melle-L-Melle-Gly-L-MeVal-L-Tyr(OMe)-] and cyclo[-(R)-2- hydroxyisovaleryl-L-pipecoly-L-Val-L-Val-L-MeAsp-L-Melle-L-Melle-Gly-L- MeVal-L-Tyr(OMe)-], respectively, by spectroscopic analyses, especially using 2D NMR techniques. The absolute stereochemistry was elucidated by the advanced Marfey's method and chiral HPLC analysis.
- Suzuki,Ojika,Sakagai,Kaida,Fudou,Kameyama
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- An efficient α-hydroxylation of carbonyls using the HOF·CH3CN complex
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The complex HOF·CH3CN, made directly from fluorine and aqueous acetonitrile, was used for α-hydroxylation of various ketones, esters and acids via their trimethyl silyl enol ethers. The reaction is usually complete in a few minutes at room temperature or below and has high yields.
- Dayan, Sharon,Bareket, Yifat,Rozen, Shlomo
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p. 3657 - 3664
(2007/10/03)
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- Enantioselectivity of Pseudomonas cepacia lipase for the acetylation of 2-hydroxy carboxylic acid esters+
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Structurally different ethyl or methyl 2-hydroxy carboxylates were resolved by Pseudomonas cepacia lipase-catalysed acetylations with vinyl acetate in diethylether. One type of the alcoholic substrates (2-hydroxy-2-arylacetates and 2-hydroxy-3-arylpropinates) contained a HO-group at the stereocentre. These compounds were resolved with high enantioselectivity (ee 91 → 99) at ca. 50% conversion. The other alcoholic substrates ((threo-2-hydroxy-3-methylbutyrate and threo- or erythro-2-hydroxy-3-aryl-3-arylthio(or aryloxy)propionates) with two stereocentres generally resulted in enantiopure products and the reactions stopped at 50 % conversion.
- Sundholm, Oskari,Kanerva, Liisa T.
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p. 625 - 640
(2007/10/03)
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- Asymmetric reactions of α-ketoacid-derived hemiacetals: Stereoselective synthesis of α-hydroxy acids
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N-Acylation of prolinol with α-ketoacid chlorides results in concomitant hemiacetalization of the α-keto amide by the prolinol hydroxyl group. (R) or (S) α-hydroxy acids are obtained with good enantiomeric excess by stereodivergent reduction of these hemiacetals. Reaction with Grignard reagents at ambient temperature furnishes (R) α-alkyl mandelic acids with good stereoselectivity.
- Pansare, Sunil V.,Ravi, R. Gnana
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p. 14549 - 14564
(2007/10/03)
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- Enantioselective synthesis of α-hydroxy carboxylic acids: Direct conversion of α-oxocarboxylic acids to enantiomerically enriched α-hydroxy carboxylic acids via neighboring group control
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α-Oxocarboxylic acids can be reduced to the corresponding α-hydroxy carboxylic acids employing DIP-CI(TM) as a reducing agent. The α-carboxylic substituent exerts a remarkable neighboring group effect on the reduction. The reaction presumably proceeds in an intramolecular fashion through a 'rigid' bicyclic transition state assembly, which produces enantioselectivities approaching 99%.
- Wang, Zhe,La, Brittany,Fortunak, Joseph M.,Meng, Xian-Jun,Kabalka, George W.
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p. 5501 - 5504
(2007/10/03)
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- Synthesis of optically active α-hydroxy acids by kinetic resolution through lipase-catalyzed enantioselective acetylation
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The lipase-catalyzed acetylation of a broad spectrum of racemic 2-hydroxy acids 1 to their 2-acetoxy acids 2 was shown to proceed with high enantioselectivity. Thus, the microbial lipases, in particular from Candida antarctica and Burkholderia species, are convenient biocatalysts for the synthesis of optically active 2-hydroxy acids in excellent enantioselectivity (ee values up to 99%). The absolute configurations of the 2-hydroxy acids 1 were assigned by comparison of the gas-chromatographic data with that of literature-known reference compounds, or by means of the exciton-coupled circular dichroism method (ECCD) on their bichromophoric 2-naphthoate 9-anthrylmethyl derivatives 3. These results establish that (S)-2-hydroxy acids 1 were preferentially acetylated by microbial lipases.
- Adam, Waldemar,Lazarus, Michael,Schmerder, Alexandra,Humpf, Hans-Ulrich,Saha-M?ller, Chantu R.,Schreier, Peter
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p. 2013 - 2018
(2007/10/03)
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- Reaction of carboxylic acids with diethyl phosphorocyanidate; a novel synthesis of homologated α-hydroxycarboxylic acids from carboxylic acids
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Carboxylic acids react with 2 equivalents of diethyl phosphorocyanidate in the presence of triethylamine to give dicyanophosphates in good yields; these dicyanophosphates can be hydrolyzed easily to give homologated α- hydroxycarboxylic acids.
- Mizuno, Masanori,Shioiri, Takayuki
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p. 9209 - 9210
(2007/10/03)
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- Derivatives of cyclodepsipeptide PF 1022
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Novel PF 1022 derivatives--cyclodepsipeptides represented by the below-described formula (I)--and acid addition salts thereof, which have been synthesized according to the present invention, have anthelmintic activities against various parasitic worms which are parasitic on human bodies, domestic animals and pet animals. They are therefore useful as anthelmintics for the prevention or treatment of parasitic infections. STR1 wherein R1, R2, R3, R4, Q, X, Y and Z have been defined herein.
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- (R)- and (S)-3-Hydroxy-4,4-dimethyl-1-phenyl-2-pyrrolidinone as chiral auxiliaries for the asymmetric synthesis of α-hydroxy acids
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Rac-α-bromo acids, rac-4, have been converted into(R)- or(S)-α-hydroxy acids, (R)- or (S)-9 by DCC-induced esterification with the chiral auxiliaries (R)or (S)-1, followed by reaction with sodium p-methoxyphenoxide in the presence of tetra-n-hexylammonium iodide, conditions of dynamic kinetic resolution, to give quite diastereoselectively the (αR,3S)- or (αS,3R)-α-(p-methoxyphenoxy) esters, 7, which were then oxidized with eerie ammonium nitrate and hydrolyzed under controlled acid conditions.
- Camps, Pelayo,Perez, Francesc,Soldevilla, Nuria
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p. 1877 - 1894
(2007/10/03)
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- Esters of L-carnitine and acyl L-carnitine with hydoxy acids for producing pharmcaeutical compositions for treating dermatoses
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Dermatosis is treated by a method comprising topically applying an effective amount of an ester of L-carnitine or an acyl L-carnitine with a hydroxy carboxylic acid selected from the group consisting of α-hydroxybutyric acid, α-hydroxyisocaproic acid, α-hydroxyisovaleric acid, malic acid and tartronic acid, to a patient in need thereof.
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- A Novel Bicyclic Orthoester as a Chiral Auxiliary: Application to the Synthesis of α-Hydroxy Acids
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Chiral α-keto orthoesters derived from tartanic acid can be reduced diastereoselectively.Hydrolysis affords optically actice α-hydroxy acids and the recovered auxiliary.
- Dube, D.,Deschenes, D.,Tweddell, J.,Gagnon, H.,Carlini, R.
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p. 1827 - 1830
(2007/10/02)
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- Making optically active alpha-hydroxy acids or precursors
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Disclosed is a process for making an α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid which comprises (1) hydrocarboxylating an enol acylate, which has a chiral C atom that is essentially all L or all D, with CO and water or an organic hydroxyl compound, thereby producing a reaction mixture containing diastereomeric α-acyloxy acids or esters having two chiral centers and having essentially no enantiomeric pairs, (2) separating the diastereomers by conventional physical means and (3) hydrolyzing at least one of said separated diastereomers to make at least the α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid. Also disclosed is a process for making an α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid which comprises (1) hydrocarboxylating an enol acylate, the enol portion of which has a chiral C atom that is essentially all L or all D, with CO and water or an organic hydroxyl compound, thereby producing a reaction mixture containing diastereomeric α-acyloxy acids or esters having two chiral centers and having essentially no enantiomeric pairs, (2) hydrolyzing the product of (1) to make a diastereomeric mixture containing α-hydroxy acids, and (3) separating by conventional physical means from the product of (2) at least one α-hydroxy acid which is essentially all L or all D with respect to the chiral C atom bonded to the carboxy group of said acid.
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- A Novel Highly Diastereoselective Synthesis of Cyano Esters by Regioselective Ring Opening of Chiral Oxazolidinium Methiodides with Sodium Cyanide
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Sodium cyanide reacts with chiral oxazolidinium methiodides, prepared by quaternization of oxazolidines with methyl iodide, leading regio- and stereoselectively (d.e. 82-94percent) to cyano esters in moderate to good chemical yields (51-95percent).The open compounds are isolated as a pure diastereomer by a single recrystallization of their ammonium methiodides, and converted into enantiomerically pure α-hydroxy acids by heating with a concentrated solution of hydrochloric acid. - Key words: Chiral Oxazolidinium Iodides; alpha-Cyano ethers, Diastereoselective Ring Opening; alpha-Hydroxy Acids; Asymmetric Synthesis.
- Andres, Celia,Delgado, Manuel,Pedrosa, Rafael,Rodriquez, Raquel
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p. 8325 - 8328
(2007/10/02)
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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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- Polyfunctional (R)-2-Hydroxycarboxylic Acids by Reduction of 2-Oxo Acids with Hydrogen Gas or Formate and Resting Cells of Proteus vulgaris
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Various (R)-2-hydroxy acids such as (R)-2-hydroxy-3-enoic-, 3,5-dienoic-, 4-oxo-, (R,S)-3-hydroxy and some others were prepared on a scale up to 0.12 mol by biocatalytic reduction of the corresponding 2-oxo acids with P. vulgaris and hydrogen gas and/or formate as electron donors.With the exception of the 2-hydroxy-4-oxo acids it could be proved that the enantiomeric excess is >97 percent.For the 4-oxo derivatives this enantiomeric excess can be assumed.The yields of isolated products are high because they were isolated from rather small amounts of biocatalyst and low buffer concentrations.Product concentrations in the range of 0.1- 0.24 M were obtained.For 1 mmol of product formation in 15-20 h about 20-40 mg (dry weight) of P. vulgaris cells are necessary.
- Schummer, Anita,Yu, Hongtao,Simon, Helmut
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p. 9019 - 9034
(2007/10/02)
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- Process for preparing optically active alcohol
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A process for preparing an optically active alcohol is disclosed, which comprises asymmetrically hydrogenating a carbonyl compound in the presence of a ruthenium-optically active phosphine complex as a catalyst. The resulting alcohol has high optical purity.
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- Photocatalytic Asymmetric Reduction of 3-Methyl-2-oxobutanoic Acid with Chiral Rh(I) Complexes and Powdery Semiconductors
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Photocatalytic asymmetric reduction of 3-methyl-2-oxobutanoic acid giving 2-hydroxy-3-methylbutanoic acid has been carried out in up to 60percent ee in aqueous methanol with chiral BINAP-Rh(I) complexes and semiconductor photocatalysts, TiO2 or CdS.
- Wang, Hanhein,Sakata, Tadayoshi,Azuma, Masashi,Ohta, Tetsuo,Takaya, Hidemasa
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p. 1331 - 1334
(2007/10/02)
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- A Regio- and stereocontrolled total synthesis of (-)-indolactam-V
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(-)-Indolactam-V (IL-V) (1)-was prepared in 10 steps from L-tryptophan methyl ester in 17.1% overall yield. The key steps involve regiospecific thallation of the acylindole intermediate (4), followed by azide displacement and reduction to introduce the 13-amino group. Control of the C-11 stereocenter was achieved by SN2 displacement of the chiral inflate (10), derived from D-valine. The thallium mediated closure of dipeptide (17) did not provide an alternative route to IL-V.
- Kogan, Timothy P.,Somers, Todd C.,Venuti, Michael C.
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p. 6623 - 6632
(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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- Method of making a diastereomeric mixture containing two diastereomeric α-acyloxy acid esters
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In the process of hydrocarboxylating an enol acylate with CO and an organic hydroxyl compound to produce an α-acyloxy acid ester, the improvement comprising using as the organic hydroxyl compound reactant, an organic hydroxyl compound which has a chiral center that is essentially all L or D, thereby producing a reaction mixture having essentially no enantiomeric pairs and containing diastereomeric α-acyloxy acid esters having two chiral centers.
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