- Synthesis of coumarins by Pt-catalyzed hydroarylation of propiolic acids with phenols
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Synthesis of coumarins from phenols and propiolic acids was examined by using a Pt catalyst such as PtCl2/AgOTf, K2PtCl4/AgOTf, and K2PtCl4/AgOAc. Propiolic acid reacted even with less reactive phenols in trifluoroacetic acid to give coumarins and dihydrocoumarins. In the case of substituted propiolic acids, phenylpropiolic acid and 2-octynoic acid, the reactions proceeded selectively to afford coumarins in good to high yields.
- Oyamada, Juzo,Kitamura, Tsugio
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- One-pot synthesis of β-keto esters and preparation of 3-ketopalmitoyl-CoA
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β-Keto esters were synthesized from acyl chlorides and sodium ethyl acetoacetate in EtOH using a simple one-pot, one-step' method. The deacetylation of α-acetyl β-keto ester to β-keto ester was performed simply, by heating the reaction mixture at reflux for 12 hours, without the addition of additional reagents (e.g., NHl, NH MeOH, or NaOH). One of the β-keto esters prepared using this method was ethyl 3-oxohexadecanoate, a key intermediate in the synthesis of 3-ketopalmitoyl coenzyme A (3-oxohexadecanoyl coenzyme A), a potential substrate of the biologically important enzyme 17β-hydroxysteroid dehydrogenase type 12. Georg Thieme Verlag Stuttgart ? New York.
- Ko?ak, Urban,Kova?, Andreja,Gobec, Stanislav
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- Isolation and crystal structures of both enol and keto tautomer intermediates in a hydration of an alkyne-carboxylic acid ester catalyzed by iridium complexes in water
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Hydration of tetrolic acid ethyl ester as an alkyne-carboxylic acid ester catalyzed by an Ir-aqua complex [IrIIICp*(bpy)(OH 2)]2+ (1, Cp* = η5-C 5Me5, bpy = 2,2′-bipyridine) in water provides ethyl acetoacetate as a β-keto acid ester. We report the successful isolation of both an Ir-enol tautomer intermediate [IrIIICp*(bpy){CH 3C(OH)=CC(O)OC2H5}]+ (2) and an Ir-keto tautomer intermediate [IrIIICp*(bpy){CH 3C(O)-CHC(O)OC2H5}]+ (3) in the catalytic hydration by optimizing the conditions of the isolation, such as pH of the solution, reaction time, and selection of counteranions. The structures of the enol and keto complexes with characteristic Ir-(sp2carbon) bond and Ir-(sp3 carbon) bond, respectively, were unequivocally determined by X-ray analysis, IR, electrospray ionization mass spectrometry (ESI-MS), and NMR studies including 1H, 13C, distortionless enhancement by polarization transfer (DEPT) and correlation spectroscopy (COSY) experiments. It was confirmed that the hydration of tetrolic acid ethyl ester catalyzed by 2 or 3 as initial catalysts provides ethyl acetoacetate. Mechanism of the catalytic hydration of tetrolic acid ethyl ester as an alkyne-carboxylic acid ester is discussed based on isotopic labeling experiments with the Ir-enol and Ir-keto tautomers.
- Kanemitsu, Hironobu,Uehara, Keiji,Fukuzumi, Shunichi,Ogo, Seiji
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- Simple synthesis of enantiomers of 6-hydroxyalkan-4-olides by stereoselective hydrogenation of methyl 4,6-dioxoalkanoates
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A simple method for the synthesis of (S,S)- or (R,R)-6-hydroxyalkan-4-olides, components of the pheromonal secretion of the butterfly Idea leuconoe, in high ee by enantioselective hydrogenation of 4,6-diketo esters with a commercial available Ru-BINAP catalyst is described.
- Schulz, Stefan
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- Molybdenum(VI) dichloride dioxide catalyzed synthesis of β-keto esters by C-H insertion of ethyl diazoacetate into aldehydes
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Synthesis of β-keto esters by condensing various aldehydes with ethyl diazoacetate is achieved by using molybdenum(VI) dichloride dioxide. Aromatic, aliphatic, and heterocyclic aldehydes are successfully condensed with ethyl diazoacetate to obtain corresponding β-keto esters in high yields at room temperature.
- Jeyakumar, Kandasamy,Chand, Dillip Kumar
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- Efficient Synthesis of Functionalized β-Keto Esters and β-Diketones through Regioselective Hydration of Alkynyl Esters and Alkynyl Ketones by Use of a Cationic NHC–AuICatalyst
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Regioselective hydration of α-alkynyl esters and ketones by using a cationic NHC–AuIcatalyst results in β-keto esters and β-diketones, respectively. Controlled release of water in acetone by aldol self-condensation under the reaction conditions makes acetone as better solvent than 1,4-dioxane/water for the hydration of α-alkynyl esters having sensitive ester moieties.
- Tarigopula, Chandrahas,Thota, Ganesh Kumar,Balamurugan, Rengarajan
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- Synthesis of 4-alkyl- and 4-(ω-chloroalkyl)-3-hydroxy-5- alkylidenebutenolides based on cyclizations of 4-alkyl- and 4-(ω- chloroalkyl)-1,3-bis(trimethylsilyloxy)buta-1,3-dienes with oxalyl chloride
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4-Alkyl- and 4-(ω-chloroalkyl)-1,3-bis(trimethylsilyloxy)buta-1,3- dienes were prepared from ethyl acetoacetate in three steps. Their cyclization with oxalyl chloride allowed an efficient synthesis of 4-alkyl- and 4-(ω-chloroalkyl)-5-alkylidenebutenolides. Georg Thieme Verlag Stuttgart.
- Nguyen, Van Thi Hong,Bellur, Esen,Appel, Bettina,Langer, Peter
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- A novel convenient route to the naturally occurring 3-oxoacyl-L-homoserinelactones and related bacterial autoinducers
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The naturally occurring 3-oxohexanoyl-L-homoserinelactone (1a), a bacterial autoinducer has been prepared in 47% overall yield by condensing stable 3-oxohexanoic acid (2), prepared by hydrolysis from the corresponding ester (3), with L-homoserinelactone using hydroxybenzotriazole (HOBT) and dicyclohexylcarbodiimide (DCC) in non-aqueous media.
- Dekhane, Mouloud,Douglas, Kenneth T.,Gilbert, Peter
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- Non-metal Lewis acid-catalyzed cross-Claisen condensation for β-keto esters
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In this work, we disclose a new catalytic and highly chemoselective cross-Claisen condensation of esters. In the presence of TBSNTf2 as a non-metal Lewis acid, various esters can undergo cross-Claisen condensation to form β-keto esters which are important building blocks. Compared with the traditional Claisen condensation, this process, employing silyl ketene acetals (SKAs) as carbonic nucleophiles to achieve cross-Claisen condensation, requires mild conditions and has good tolerance of functional groups. This journal is
- Han, Zhengyu,Huang, Hai,Meng, Fuliang,Yang, Zhenkun,Zhang, Tianyu,Zhou, Dapeng
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supporting information
p. 9163 - 9166
(2021/11/16)
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- Synthetic Scope of Br?nsted Acid-Catalyzed Reactions of Carbonyl Compounds and Ethyl Diazoacetate
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The comprehensive study of the reactions of carbonyl compounds and ethyl diazoacetate in the presence of a Br?nsted acid catalyst is described. In result, a broad range of 3-oxo-esters were synthesized from a variety of ketones and aliphatic aldehydes by 1,2-aryl/alkyl/hydride shift. Aryl-methyl ketones produced only aryl-migrated products, whereas other ketones yielded a mixture of products. For diaryl ketones, the identity of two inseparable migrated products was confirmed by two-dimensional NMR spectroscopy.
- Rahaman, Mizzanoor,Ali, M. Shahnawaz,Jahan, Khorshada,Hinz, Damon,Belayet, Jawad Bin,Majinski, Ryan,Hossain, M. Mahmun
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p. 6138 - 6147
(2021/05/06)
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- Synthesis and Pharmacological Evaluation of Triazolopyrimidinone Derivatives as Noncompetitive, Intracellular Antagonists for CC Chemokine Receptors 2 and 5
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CC chemokine receptors 2 (CCR2) and 5 (CCR5) are involved in many inflammatory diseases; however, most CCR2 and CCR5 clinical candidates have been unsuccessful. (Pre)clinical evidence suggests that dual CCR2/CCR5 inhibition might be more effective in the treatment of such multifactorial diseases. In this regard, the highly conserved intracellular binding site in chemokine receptors provides a new avenue for the design of multitarget ligands. In this study, we synthesized and evaluated the biological activity of a series of triazolopyrimidinone derivatives in CCR2 and CCR5. Radioligand binding assays first showed that they bind to the intracellular site of CCR2, and in combination with functional assays on CCR5, we explored structure-affinity/activity relationships in both receptors. Although most compounds were CCR2-selective, 39 and 43 inhibited β-arrestin recruitment in CCR5 with high potency. Moreover, these compounds displayed an insurmountable mechanism of inhibition in both receptors, which holds promise for improved efficacy in inflammatory diseases.
- Ortiz Zacarías, Natalia V.,Van Veldhoven, Jacobus P. D.,Den Hollander, Lisa S.,Dogan, Burak,Openy, Joseph,Hsiao, Ya-Yun,Lenselink, Eelke B.,Heitman, Laura H.,Ijzerman, Adriaan P.
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p. 11035 - 11053
(2019/12/24)
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- Screening, synthesis, crystal structure, and molecular basis of 6-amino-4-phenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles as novel AKR1C3 inhibitors
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AKR1C3 is a promising therapeutic target for castration-resistant prostate cancer. Herein, an evaluation of in-house library discovered substituted pyranopyrazole as a novel scaffold for AKR1C3 inhibitors. Preliminary SAR exploration identified its derivative 19d as the most promising compound with an IC50 of 0.160 μM among the 23 synthesized molecules. Crystal structure studies revealed that the binding mode of the pyranopyrazole scaffold is different from the current inhibitors. Hydroxyl, methoxy and nitro group at the C4-phenyl substituent together anchor the inhibitor to the oxyanion site, while the core of the scaffold dramatically enlarges but partially occupies the SP pockets with abundant hydrogen bond interactions. Strikingly, the inhibitor undergoes a conformational change to fit AKR1C3 and its homologous protein AKR1C1. Our results suggested that conformational changes of the receptor and the inhibitor should both be considered during the rational design of selective AKR1C3 inhibitors. Detailed binding features obtained from molecular dynamics simulations helped to finally elucidate the molecular basis of 6-amino-4-phenyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitriles as AKR1C3 inhibitors, which would facilitate the future rational inhibitor design and structural optimization.
- Zheng, Xuehua,Jiang, Zan,Li, Xiaolin,Zhang, Chen,Li, Zhe,Wu, Yinuo,Wang, Xinhua,Zhang, Chao,Luo, Hai-bin,Xu, Jun,Wu, Deyan
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p. 5934 - 5943
(2018/11/23)
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- Pyrazole alcohol compound, pharmaceutical composition thereof and application thereof to drugs
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The invention discloses a 1-(3,5,6-trimethyl pyrazine-2-yl)-5-pyrazole alcohol compound, a tautomer thereof, a pharmaceutical composition thereof and application thereof to drugs. The 1-(3,5,6-trimethyl pyrazine-2-yl)-5-pyrazole alcohol compound has double effects of resisting platelet aggregation and protecting nerve cells, and comprises a compound as shown in the formula (I), a tautomer (Ia) thereof, or a stereoisomer, a geometrical isomer, a hydrate or a solvate thereof, or a pharmaceutically acceptable salt or prodrug as shown in the description. The 1-(3,5,6-trimethyl pyrazine-2-yl)-5-pyrazole alcohol compound and the pharmaceutical composition thereof provided by the invention can be used for preparing drugs for prevention and/or treatment and/or auxiliary treatment of cerebral apoplexy, cardiovascular and cerebrovascular diseases, senile dementia and complications thereof caused by thrombosis and excessive free radicals.
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Paragraph 0128; 0130
(2018/10/19)
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- Expanding Blaise-Type Reactions towards Indium-Mediated Transformations of α-Bromo-β-keto Esters with Nitriles
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The aim of this work is the identification of mild reaction conditions for the Blaise-type transformation of brominated β-keto esters with nitriles to generate enamino-substituted keto esters. The best results were obtained when a combination of indium metal (0.7 equiv.) with indium trichloride (1.6 equiv.) were applied at 60 °C for 20 to 72 hours, and these conditions could be applied to a broad range of nitriles and a significant number of different β-keto esters. The transformation of aliphatic nitriles proved to be difficult and gave only moderate yields. However, aromatic nitriles gave good yields in many cases. The applicability range of β-keto esters is acceptable while some electron-deficient aryl-substituents on the keto ester were challenging substrates. Nevertheless, we were able to expand the scope of the Blaise-type reaction towards brominated β-keto esters significantly.
- Li, Luomo,Babaoglu, Emre,Harms, Klaus,Hilt, Gerhard
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supporting information
p. 4543 - 4547
(2017/08/30)
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- A Formal Synthesis of (-)-Perhydrohistrionicotoxin Using a Cross Metathesis-Hydrogenation Approach
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The development of an efficient, high yielding six-step convergent synthesis of the semisynthetic alkaloid (-)-perhydrohistrionicotoxin is described. The key transformations include the cross metathesis of a Br?nsted-acid masked primary homoallylic amine with a vinyl cyclohexenone and a regioselective palladium catalyzed hydrogenation. This sequence generated the advanced Winterfeldt spirocyclic precursor in 47% overall yield, with a longest linear sequence of five steps.
- Spiccia, Nicolas D.,Burnley, James,Subasinghe, Kamani,Perry, Christopher,Lefort, Laurent,Jackson, W. Roy,Robinson, Andrea J.
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p. 8725 - 8732
(2017/08/23)
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- Synthesis of the 1,3,4-Oxadiazole Core through Thermolysis of Geminal Diazides
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The thermolysis of geminal diazides derived from acylacetate compounds is an efficient tool for the rapid construction of the 1,3,4-oxadiazole core. While a broad range of ethyl esters undergoes smooth transformation to the desired heterocycles that contain the ester moiety in moderate to high yields, the analogous tert-butyl esters give rise to the oxadiazoles with acyl groups, presumably through a pathway of decarboxylation followed by a new acyl transfer.
- Erhardt, Hellmuth,Mohr, Fabian,Kirsch, Stefan F.
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supporting information
p. 5629 - 5632
(2016/12/14)
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- Total synthesis and structural validation of cyclodepsipeptides solonamide A and B
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Microorganisms are an attractive source of new natural products with antimicrobial properties, and the marine environment constitutes a prolific resource of bioactive microorganisms. During a global research expedition (Galathea III), two depsipeptides, solonamide A and solonamide B, were isolated from the marine bacterium Photobacterium halotolerance and were found to inhibit virulence gene expression in the serious human pathogen, Staphylococcus aureus. They act by interfering with the agr quorum sensing system and show resemblance to the endogenous S. aureus quorum sensing peptide, autoinducing peptide I (AIP-I). To enable more comprehensive studies, we embarked on the chemical synthesis of solonamides A and B. The key synthetic steps were formation of the (R)-β-hydroxy-fatty-acids by stereo-selective aldol reactions and a cyclative macrolactamization, which proceeded under highly dilute conditions. Thus, the first total syntheses of the solonamides corroborated the originally assigned structures, and by changing the stereochemistry of the auxiliary in the aldol steps we gained access to the natural products as well as their β3-epimers.
- Kitir, Betül,Baldry, Mara,Ingmer, Hanne,Olsen, Christian A.
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p. 7721 - 7732
(2014/12/10)
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- AMIDE COMPOUND AND BACTERIAL DISEASE CONTROL AGENT FOR AGRICULTURAL AND HORTICULTURAL USE
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The present invention provides an amide compound having antibacterial activity, and a bacterial infection control agent for agricultural and horticultural use that contains the amide compound. The novel amide compound of the present invention is represented by General Formula (1): wherein R is a -CH(R1)(R2) or a -CO(R2) group, R1 is a hydrogen atom or a hydroxyl group, and R2 is a C1-12 alkyl group.
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Page/Page column 9
(2010/09/05)
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- Affinity of 3-acyl substituted 4-quinolones at the benzodiazepine site of GABAA receptors
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The finding that alkyl 1,4-dihydro-4-oxoquinoline-3-carboxylate and N-alkyl-1,4-dihydro-4-oxoquinoline-3-carboxamide derivatives may be high-affinity ligands at the benzodiazepine binding site of the GABAA receptor, prompted a study of 3-acyl-1,4-dihydro-4-oxoquinoline (3-acyl-4-quinolones). In general, the affinity of the 3-acyl derivatives was found to be comparable with the 3-carboxylate and the 3-carboxamide derivatives, and certain substituents (e.g., benzyl) in position 6 were again shown to be important. As it is believed that the benzodiazepine binding site is situated between an α- and a γ-subunit in the GABAA receptor, selected compounds were tested on the α1β2γ2s, α2β2γ2s and α3β2γ2s GABAA receptor subtypes. The 3-acyl-4-quinolones display various degrees of selectivity for α1- versus α2- and α3-containing receptors, and high-affinity ligands essentially selective for α1 over α3 were developed.
- Lager, Erik,Nilsson, Jakob,stergaard Nielsen, Elsebet,Nielsen, Mogens,Liljefors, Tommy,Sterner, Olov
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p. 6936 - 6948
(2008/12/21)
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- Synthesis of novel &β-lactone inhibitors of fatty acid synthase
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Fatty acid synthase (FAS) is necessary for growth and survival of tumor cells and is a promising drug target for oncology. Here, we report on the syntheses and activity of novel inhibitors of the thioesterase domain of FAS. Using the structure of orlistat as a starting point, which contains a β-lactone as the central pharmacophore, 28 novel congeners were synthesized and examined. Structural features such as the length of the α- and β-alkyl chains, their chemical composition, and amino ester substitutions were altered and the resulting compounds explored for inhibitory activity toward the thioesterase domain of FAS. Nineteen congeners show improved potency for FAS in biochemical assays relative to orlistat. Three of that subset, including the natural product valilactone, also display an increased potency in inducing tumor cell death and improved solubility compared to orlistat. These findings support the idea that an orlistat congener can be optimized for use in a preclinical drug design and for clinical drug development.
- Richardson, Robyn D.,Knowles, Lynn M.,Cieplak, Piotr,Smith, Jeffrey W.,Ma, Gil,Oyola, Yatsandra,Zancanella, Manuel,Romo, Daniel
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scheme or table
p. 5285 - 5296
(2010/04/02)
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- Preparation of β-keto esters and β-diketones by C-acylation/deacetylation of acetoacetic esters and acetonyl ketones with 1-acylbenzotriazoles
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Acyl-, aroyl-, and heteroaroyl-acetic esters 6a-f and 8a-1 are prepared by reactions of 1-acylbenzotriazoles 1a-k with acetoacetic esters 5 or 7a,b in the presence of sodium hydride followed by regioselective deacetylation. Similar C-acylation/deacetylati
- Katritzky, Alan R.,Wang, Zuoquan,Wang, Mingyi,Wilkerson, Chavon R.,Hall, C. Dennis,Akhmedov, Novruz G.
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p. 6617 - 6622
(2007/10/03)
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- Nitroalkanes and ethyl glyoxalate as common precursors for the preparation of both β-keto esters and α,β-unsaturated esters
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β-Nitro acrylic esters, obtained by the reaction of nitroalkanes and ethyl glyoxalate, are the key building blocks for the immediate synthesis of both the title compounds. In fact, their treatment with titanium trichloride produce the direct conversion to the β-keto esters, while their reaction with sodium boron hydride gives the one-pot synthesis of α,β- unsaturated esters through formal substitution of the vinylic nitro group with an hydrogen.
- Ballini, Roberto,Fiorini, Dennis,Palmieri, Alessandro
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p. 7027 - 7029
(2007/10/03)
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- Method for preparing chiral diphosphines
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The invention concerns a method for preparing a compound of formula (1) wherein: A represents naphthyl or phenyl optionally substituted; and Ar1, Ar2independently represent a saturated or aromatic carbocyclic group, optionally substituted.
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- Absolute configuration and synthesis of β- and δ-lactones present in the pheromone system of the giant white butterfly Idea leuconoe
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Males of the giant white butterfly Idea leuconoe release a complex mixture of compounds during courtship. Besides alkaloids, aromatics, terpenoids and hydrocarbons, several lactones have been identified in the pheromone bouquet. Two simple stereoselective methods to create the lactones in good enantiomeric excesses have been developed. The generation of the stereocenters of the β-lactones la and lb is based on a controlled C-C coupling by a Horner-Wadsworth-Emmons approach, followed by asymmetric dihydroxylation, whereas the synthesis of the δ-lactone 3b uses an enantioselective hydrogenation of a dioxoalkanoate precursor. The absolute configurations of the natural lactones 1a, 1b and 3b were determined by gas chromatography on a chiral stationary phase. Both 1a and 1b are of (S,S) configuration, suggesting their biosynthetic origin from (-)-viridifloric acid (7a) or (-)norviridifloric acid (7b), respectively. In contrast, natural 3b is a mixture of all enantiomers, in which the (5S,7S) enantiomer dominates. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Stritzke, Katja,Schulz, Stefan,Nishida, Ritsuo
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p. 3884 - 3892
(2007/10/03)
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- Enantioselective synthesis of the key intermediate of the acyl-CoA: Cholesterol acyltransferase (ACAT) inhibitor (R-106578) using 2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl (BINAP)-Ru(OAc)2 as a catalyst
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Acidic segment of an acyl-CoA: cholesterol acyltransferase (ACAT) inhibitor, R-106578 was synthesized by enantioselective hydrogenation of the Z-olefine (9-(Z)) using (R)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP)-Ru(OAc)2 as a catalys
- Murakami,Kobayashi,Hirai
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p. 1567 - 1569
(2007/10/03)
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- Asymmetric hydrogenation method of a ketonic compound and derivative
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The present invention relates to a process for the asymmetric hydrogenation of a ketonic compound and derivative. The invention relates to the use of optically active metal complexes as catalysts for the asymmetric hydrogenation of a ketonic compound and derivative. The process for the asymmetric hydrogenation of a ketonic compound and derivative is characterized in that the asymmetric hydrogenation of said compound is carried out in the presence of an effective amount of a metal complex comprising as ligand an optically active diphosphine corresponding to one of the following formulae: STR1
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- Formal synthesis of (-)-syringolide 1 starting from D-xylose based on a biomimetic strategy
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An expeditious and practical synthertic process for a nonproteinaceous elicitor, (-)-syringolide 1, has been developed in a short number of steps utilizing the putative biosynthetic pathway by featuring the elaboration of the protected D-xylose as a starting material.
- Yoda, Hidemi,Kawauchi, Miho,Takabe, Kunihiko,Hosoya, Ken
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p. 1895 - 1898
(2007/10/03)
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- An efficient synthesis of novel N-acetyl-3-alkanoyl and 3-dienoyl tetramic acids
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A general synthesis of N-acetyl-3-alkanoyl- and 3-dienoyl-tetramic acids is presented. The condensation of N-(N-acetylglycyloxy)succinimide with β-keto esters bearing alkanoyl or dienoyl groups furnishes the new 3-substituted N-acetyltetramic acids 6-9 and 16 in good yields. The key intermediates 4 and 5 have been isolated and subsequently cyclized to the corresponding tetramic acids. Spectral data for and the physical characteristics of all compounds are reported.
- Petroliagi, Margarita,Igglessi-Markopoulou, Olga
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p. 3543 - 3548
(2007/10/03)
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- SUBSTITUTED QUINOLINES AS ANGIOTENSIN II ANTAGONISTS
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Substituted quinolines of the formula (I), are angiotensin II antagonists, STR1 and useful in the treatment of hypertension, ocular hypertension and certain CNS disorders.
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- The conversion of olefins to β-keto esters: Ozonolysis of olefins followed by in situ reduction with tin(II) chloride in the presence of ethyl diazoacetate
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Trisubstituted olefins are converted to β-keto esters by treatment with ozone followed by the addition of tin(H) chloride and ethyl diazoacetate. Monosubstituted olefins are first treated with ozone in the presence of methanol to generate methoxy hydroperoxides. The hydroperoxides are subsequently reduced with tin(II) chloride in the presence of ethyl diazoacetate to produce β-keto esters.
- Holmquist, Christopher R.,Roskamp, Eric J.
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p. 4991 - 4994
(2007/10/02)
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- Synthesis of optically active forms of the δ-lactone of 3,5-dihydroxydecanoic acid
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The δ-lactone of 3,5-dihydroxydecanoic acid was synthesized from methyl-3-oxooctanoate by utilizing its baker's yeast reduction.
- Sato, Tsuguo
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p. 2732 - 2733
(2007/10/02)
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- Synthesis of Mammea Coumarins. Part 1. The Coumarins of the Mammea A, B, and C Series
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The naturally-occuring Mammea coumarins of the 4-phenyl-(mammea A), propyl-(mammea B), and 4-pentyl-(mammea C) series have been prepared by Pechmann condensation of an acylphloroglucinol (3-methylbutyryl-, 2-methylbutyryl-, butyryl-, or 2-methylpropionyl-) with the appropriate β-ketoester to give a mixture of 6- and 8-acyl-5,7-dihydroxycoumarins that could be separated.C-Alkylation with 3-methylbut-2-enyl bromide, or 3,7-dimethylocta-2,6-dienyl chloride, in aqueous potassium hydroxide completed the synthesis of the Mammea coumarins having unmodified prenyl or geranyl substituents; oxidative modification of the prenyl group led to the mammea cyclo E and cyclo F coumarins.Some mammea cyclo D (chromeno) coumarins were synthesized by reaction of acylcoumarins with 1,1-dimethoxy-3-methylbutan-3-ol.
- Crombie, Leslie,Jones, Raymond C. F.,Palmer, Christopher J.
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p. 317 - 332
(2007/10/02)
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- Synthesis and Liquid Crystalline Phases of Pyridazine Derivatives I
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Seven pyridazine compounds were synthesized.The compounds have a general structure R-X-Y-PZ-R', where PZ is 3,6 disubstituted pyridazine ring, X and Y are either trans cyclohexyl or phenyl rings, R and R' are n-alkyl groups.The structure assignments were confirmed by carbon 13 nmr.Their liqiuid crystalline properties were evaluated.All of them have mesophases with a broad temperature range.
- Liang, Jason C.,Cross, Julie O.
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p. 123 - 130
(2007/10/02)
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- Metabolites of the Higher Fungi. Part 22. 2-Butyl-3-methylsuccinic Acid and 2-Hexylidene-3-methylsuccinic Acid from Xylariaceous Fungi
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2-Butyl-3-methylsuccinic acid has been isolated from the culture medium of Hypoxylon illitum. 2-Hexylidene-3-methylsuccinic acid is the major metabolite produced by Poronia piliformis, H. deustum, and four Xylaria species.Methods for the synthesis of the diacids are examined.
- Anderson, John R.,Edwards, Raymond L.,Whalley, Anthony J.S.
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p. 1481 - 1486
(2007/10/02)
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- Synthesis of Sulphur-containing Carbaprostacyclin Analogues
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The synthesis of PGI2 analogues, containing a sulphur atom at C(11) and a methylene group in place of oxygen atom at position 9 is reported.The synthetic approach employed as starting material tetrahydro-cis-cyclopentathiophen-5-one ethylene ketal, 5, a convenient preparation of which is also described.The introduction of the α side chain was achieved through a conventional Wittig reaction, while the ω chain was delivered by an aldolization reaction of the anion derived from sulphoxide 6 with 3,3-ethylenedioxyoctanal, follwed by suitable treatments.The stereochemical outcome of this reaction, which secured the correct stereochemistry of the chain, is briefly discussed.
- Baraldi, Pier Giovanni,Barco, Achille,Benetti, Simonetta,Gandolfi, Carmelo A.,Pollini, Gian Piero,et al.
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p. 177 - 184
(2007/10/02)
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- Versatile Route to Substituted Ketones through Charge-Directed Conjugate Addition Reactions
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Charge-directed conjugate addition reactions have been applied to the preparation of highly substituted ketones.Acylphosphoranes resulting from conjugate addition-alkylation reactions are reduced by Al-Hg to β-keto esters, which, upon alkylation and hydrolysis, give ketones in high yields.An application of this methodology to the synthesis of 9, the defense substance of L. longipes, is described.
- Cooke, Manning P.
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p. 4963 - 4968
(2007/10/02)
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- 1,4-Dithiinoxides
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1,4-Dithiinoxides which may be substituted with various radicals, compositions containing said products and methods useful in the treatment of ulcers are disclosed. The products are prepared by oxidation of the correspondingly substituted dithiin.
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