- Catalytic asymmetric [3+2] cycloaddition of isomünchnones with methyleneindolinones
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An efficient enantioselective [3+2] cycloaddition of isomünchnones with methyleneindolinones that are generated by anin situintramolecular addition of the carbonyl group to rhodium carbenes is realized with a chiralN,N′-dioxide/Zn(ii) complex as a Lewis acid. A series of chiral oxa-bridged 3-spiropiperidines are obtained in high yields with excellent dr and excellent ee values.
- Feng, Xiaoming,Hu, Xinyue,Lin, Lili,Wang, Kaixuan,Xu, Chaoran,Zhou, Yuqiao
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supporting information
p. 8917 - 8920
(2021/09/10)
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- Selective Construction of C?C and C=C Bonds by Manganese Catalyzed Coupling of Alcohols with Phosphorus Ylides
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Herein, we report the manganese catalyzed coupling of alcohols with phosphorus ylides. The selectivity in the coupling of primary alcohols with phosphorus ylides to form carbon-carbon single (C?C) and carbon-carbon double (C=C) bonds can be controlled by the ligands. In the conversion of more challenging secondary alcohols with phosphorus ylides the selectivity towards the formation of C?C vs. C=C bonds can be controlled by the reaction conditions, namely the amount of base. The scope and limitations of the coupling reactions were thoroughly evaluated by the conversion of 21 alcohols and 15 ylides. Notably, compared to existing methods, which are based on precious metal complexes as catalysts, the present catalytic system is based on earth abundant manganese catalysts. The reaction can also be performed in a sequential one-pot reaction generating the phosphorus ylide in situ followed manganese catalyzed C?C and C=C bond formation. Mechanistic studies suggest that the C?C bond was generated via a borrowing hydrogen pathway and the C=C bond formation followed an acceptorless dehydrogenative coupling pathway. (Figure presented.).
- Liu, Xin,Werner, Thomas
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p. 1096 - 1104
(2020/12/31)
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- DMAP Mediated Efficient Construction of Functionalized Chromenes through One-Pot Reaction of para-Quinone Methides with Allenoates
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A novel DMAP-mediated Rauhut-Currier/oxa-Michael addition cascade reaction of hydroxylphenyl-substituted para-quinone methide with allenoate was reported for the first time. A series of functionalized chromenes were successfully obtained with moderate to
- Song, Zefeng,Jia, Yuping,Zhang, Daizhou,Wang, De
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supporting information
p. 1942 - 1948
(2021/04/05)
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- Enantioselective Rauhut–Currier Reaction with β-Substituted Acrylamides Catalyzed by N-Heterocyclic Carbenes
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β-Substituted acrylamides have low electrophilicity and are yet to be exploited in the enantioselective Rauhut–Currier reaction. By exploiting electron-withdrawing protection of the amide and moderate nucleophilicity N-heterocyclic carbenes, such substrates have been converted to enantioenriched quinolones. The reaction proceeds with complete diastereoselectivity, good yield, and modest enantioselectivity. Derivatizations are reported, as are computational studies, supporting decreased amide bond character with electron-withdrawing protection of the nitrogen.
- Pitchumani, Venkatachalam,Breugst, Martin,Lupton, David W.
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supporting information
p. 9413 - 9418
(2021/12/09)
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- Side-Chain Modification of Peptides Using a Phosphoranylidene Amino Acid
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The flexible variation of peptidomimetics is of great interest for the identification of optimized protein ligands. Here we present a general concept for introducing side-chain modifications into peptides using triarylphosphonium amino acids. Building blo
- Accorsi, Matteo,Ahsanullah,Masri, Enaam,Rademann, J?rg
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supporting information
(2020/04/15)
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- Asymmetric Catalytic Diverse Ring Opening/Cycloadditions of Cyclobutenones with (E)-Alkenyloxindoles and (E)-Dioxopyrrolidines
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Highly enantioselective ring-opening/cycloaddition reactions of cyclobutenones were achieved by employing chiral N,N′-dioxide/metal complexes as the catalysts. The Diels-Alder type cycloaddition with (E)-alkenyloxindoles yielded spirocyclohexaneoxindoles with excellent results. Meanwhile, a hetero-Diels-Alder process occurred with (E)-dioxopyrrolidines to afford spiropyrrolidinone-dihydropyranone derivatives.
- Luo, Yao,Zhang, Hang,Wang, Siyuan,Zhou, Yuqiao,Dong, Shunxi,Feng, Xiaoming
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supporting information
p. 2645 - 2650
(2020/04/02)
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- Phosphine-catalyzed dearomative [3+2] annulation of 3-nitroindoles and allenoates
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The efficient phosphine-catalyzed dearomative [3+2] annulation of 3-nitroindoles with allenoates has been successfully developed, providing a facile access to cyclopenta[b]indolines with good to excellent yields and high diastereoselectivities. This strategy features mild reaction conditions, high functional group tolerance, and scalability. Additionally, the 2-nitrobenzofuran and 2-nitrobenzothiophene were good dearomative [3+2] annulation partners.
- Liu, Kui,Wang, Gang,Cheng, Shao-Jie,Jiang, Wen-Feng,He, Cheng,Ye, Zhi-Shi
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supporting information
p. 1885 - 1890
(2019/06/21)
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- A Ba/Pd Catalytic System Enables Dehydrative Cross-Coupling and Excellent E-Selective Wittig Reactions
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A Ba/Pd cooperative catalysis system was developed to enable the dehydrative cross-coupling of allylic alcohols with P-ylides to occur directly and promote a subsequent Wittig reaction in one pot. A variety of multisubstituted 1,4-dienes were isolated in good to excellent yields with broad P-ylides (stabilized by both ester and ketone carbonyl groups) and aldehyde (aliphatic and aromatic) substrates with excellent E selectivity.
- Xie, Peizhong,Fu, Weishan,Cai, Xinying,Sun, Zuolian,Wu, Ying,Li, Shuangshuang,Gao, Cuiqing,Yang, Xiaobo,Loh, Teck-Peng
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supporting information
p. 7055 - 7059
(2019/09/12)
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- A Tunable Route to Prepare α,β-Unsaturated Esters and α,β-Unsaturated-γ-Keto Esters through Copper-Catalyzed Coupling of Alkenyl Boronic Acids with Phosphorus Ylides
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A tunable strategy to prepare α,β-unsaturated esters and α,β-unsaturated-γ-keto esters in good to excellent yields was developed through copper-catalyzed oxidative coupling of phosphorus ylides with alkenyl boronic acids under mild conditions. The reaction without water afforded α,β-unsaturated esters, ketones, and amides while α,β-unsaturated-γ-keto esters, 1,4-α,β-unsaturated diketones and α,β-unsaturated-γ-keto amides were obtained when using 5.0 equiv. of water. H2O18 labeling experiments showed that water played an important role in the formation of α,β-unsaturated-γ-keto esters. A plausible formation mechanism for α,β-unsaturated esters and α,β-unsaturated-γ-keto esters was proposed based on mechanistic studies. Phosphonium salts could also be used directly as coupling partners instead of phosphorus ylides. The reaction exhibited a broad substrate scope, good functional group tolerance, good regioselectivity, and diverse coupling products. (Figure presented.).
- Bi, Hong-Yan,Liu, Feng-Ping,Liang, Cui,Su, Gui-Fa,Mo, Dong-Liang
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supporting information
p. 1510 - 1516
(2018/03/05)
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- Methyl caffeate as an α-glucosidase inhibitor from solanum torvum fruits and the activity of related compounds
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In screening experiments for rat intestinal α-glucosidase (sucrase and maltase) inhibitors in 325 plants cultivated in Japan's southern island, of Tanegashima, marked inhibition against both sucrase and maltase was found in the extract of the fruit of Solanum torvum. Enzyme-assay guided fractionation of the extract led to the isolation of methyl caffeate (1) as a rat intestinal sucrase and maltase inhibitor. We examined 13 caffeoyl derivatives for sucrase- and maltase-inhibitory activities. The results showed that methyl caffeate (1) had a most favorable structure for both sucrase and maltase inhibition, except for a higher activity of methyl 3,4,5-trihydroxycinnamate (14) against sucrase. Its moderate inhibitory action against α-glucosidase provides a prospect for antidiabetic usage of S. torvum fruit.
- Takahashi, Keisuke,Yoshioka, Yasuyuki,Kato, Eisuke,Katsuki, Shigeki,Iida, Osamu,Hosokawa, Keizo,Kawabata, Jun
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experimental part
p. 741 - 745
(2011/07/08)
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- A facile, one-pot synthesis of lacidipine using in situ generation of wittig intermediates
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An improved, one-pot process for the preparation of lacidipine (1) via an efficient in situ generation of Wittig intermediates is reported. Generation of ylide (4) by dehydrobromination of phosphonium salt (3) followed by in situ condensation of 4 with o-phthalaldehyde (5) to yield corresponding olefin (6) and its subsequent reaction with crotonate derivative (7) in the same pot furnished the drug substance 1 with an overall yield of about 51% over the reported yield of about 24% starting from the corresponding ylide. The present work overcomes the challenges associated with prior art processes such as chromatographic purifications, handling of unstable intermediates, and formation of byproducts as potential impurities. The interesting insights on the safety aspects of the process, drawn through calorimetric studies, rendered the successful implementation of the process at manufacturing facility.
- Prasada Raju,Ravindra, Vedantham,Mathad, Vijayavitthal T.,Dubey,Reddy, Padi Pratap
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experimental part
p. 710 - 715
(2010/04/22)
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- Thermal decomposition of triphenylphosphonium alkyl ester salts
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In thermolyses of molten triphenylphosphonium alkyl ester bromides and chlorides, alkyl = methyl, ethyl, isopropyl, at 130 and 225°C, initial attack of the halide ion on the methyl group gives the methyl halide and ylid 1, Ph3P = CH2, which can be methylated, or is protonated by the phosphonium salt with transylidation giving Ph3P+-CH3X-, X = Br, Cl. The initial reactions of the ethyl or isopropyl esters are with the halide ion, X-, as a base giving ylid, 1, which can be protonated by HX or by transylidation. The t-butyl ester generates Ph3P+-CH3X-but no products of transylidation. The first-formed ylid1, can be trapped by reactive alkyl and acyl halides, and the transient ylidic esters decompose thermally to triphenyl phosphine oxide, Ph3P = O, react further with unreacted phosphonium ester, or are trapped by added aldehyde in a Wittig reaction. The final product compositions are affected by a decrease in pressure, due to escape of volatile intermediates, and by replacement of the X- halide ion by the less nucleophilic and basic tosylate ion. Reactions under reflux, in solution in chloroform, or in suspension in benzene, are similar to those of the molten salts, but yields are generally lower at the lower temperatures. Copyright Taylor & Francis Group, LLC.
- Castaneda, Fernando,Aliaga, Christian,Acuna, Cristina,Silva, Paul,Bunton, Clifford A.
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experimental part
p. 1188 - 1208
(2009/04/16)
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- Esters as acylating reagent in a Friedel-Crafts reaction: Indium tribromide catalyzed acylation of arenes using dimethylchlorosilane
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(Chemical Equation Presented) The Friedel-Crafts acylation of arenes with esters by dimethylchlorosilane and 10 mol % of indium tribromide has been achieved. The key intermediate RCOOSi(Cl)Me2 is generated from alkoxy esters with the evolution of the corresponding alkanes. The scope of the alkoxy ester moiety was wide: tert-butyl, benzyl, allyl, and isopropyl esters were successful. In addition, we demonstrated the direct synthesis of the indanone intermediate 11 of salviasperanol from ester 10.
- Nishimoto, Yoshihiro,Babu, Srinivasarao Arulananda,Yasuda, Makoto,Baba, Akio
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supporting information; experimental part
p. 9465 - 9468
(2009/04/06)
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- Antibiotic-Bound Poly(Caprolactone) Polymer
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This invention is the design and synthesis of a caprolactone monomer which bears a pendant protected carboxyl group. This monomer has been copolymerized with caprolactone in varying ratios. After polymerization, the protecting group can be removed and an antibiotic can be attached as a new pendant group. The bioactivity of the antibiotic-bound poly(caprolactone) polymer is described.
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Page/Page column 4
(2008/06/13)
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- PROCESS FOR PREPARING LACIDIPINE
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A process for preparing lacidipine, comprising reacting a t-butoxy carbonyl methyl aryl phosphonium halide with o-phthalaldehyde, and further reacting a product comprising (E)-3-(2-formylphenyl)-2-propenoic acid, 1,1-dimethyl ethyl ester, without isolation, with ethyl-3-amino crotonate.
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Page/Page column 5
(2010/11/25)
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- Rapid and efficient access to meso-2,5-cis-disubstituted pyrrolidines by double aza-Michael reactions of chiral primary amines
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The double aza-Michael reaction of enantiopure primary amines on bis α,β-unsaturated diesters has been studied under various activating conditions. High pressure allowed a rapid and efficient access to meso-2,5-disubstituted pyrrolidines.
- Cabral dos Santos, Leila,Bahlaouan, Zineb,El Kassimi, Khadija,Troufflard, Claire,Hendra, Frederic,Delarue-Cochin, Sandrine,Zahouily, Mohamed,Cave, Christian,Joseph, Delphine
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experimental part
p. 751 - 768
(2009/09/25)
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- Mechanism of toxicity of esters of caffeic and dihydrocaffeic acids
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Ten esters each of caffeic acid and dihydrocaffeic acid have recently been synthesized. Cytotoxicity evaluations of these esters versus L1210 leukemia and MCF-7 breast cancer cells in culture have led to the delineation of substantially different QSAR for each series. The L1210 QSAR for dihydrocaffeic acid esters resembles the QSAR obtained for simple phenols and estrogenic phenols. However, the QSAR pertaining to the caffeic acid esters differs considerably from its sister QSAR. This difference may be attributed to the presence of the olefinic linkage in the side chain. The octyl ester of caffeic acid is nearly ten times as toxic to the leukemia cells than the widely studied phenethyl ester, CAPE.
- Etzenhouser, Beth,Hansch, Corwin,Kapur, Sanjay,Selassie
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p. 199 - 209
(2007/10/03)
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- Novel pesticides, preparation and use
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The specification describes and claims methods of controlling acarine pests by application of a compound of Formula (I), methods of controlling arthropod pests by application of a compound of Formula (IA), compounds of Formula (IA) per se, pesticidal compositions comprising a compound of Formula (IA), and processes for preparing a compound of Formula (IA).
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- Chemistry of Cumulenes, 6. Syntheses and Reactions of 1-H-Allene-1,3-dicarboxylic Acid Monoesters
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The title compounds 5a-e have been prepared.The carboxylation of allene monoesters 4 was successful with the phenyl derivative 4a only.The resulting extremely unstable halfester 5a as its benzylammonium salt was spontaneously transformed into the enamine ester 7.The alkyl-substituted allenes 5b-e are accessible via Wittig reaction of alkylmalonic monoester chlorides 11 with (alkoxycarbonyl)methylene ylides 12, which comprise the 2,2,2-trichloroethyl or the tert-butyl residues as selectively cleavable carboxylic protecting groups.Cleavage of the CCl3CH2 group with Zn succeeded for the tert-butylallenes 13a/b only.In the case of the methylallene 13c the cleavage was accompanied by hydrogenation of the allene.The mechanism of this reaction is discussed.Cleavage of the tert-butyl ester group in 13d and e was readily achieved with ether/sulfuric acid.
- Nader, Franz W.,Brecht, Angelika,Kreisz, Siegfried
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p. 1196 - 1207
(2007/10/02)
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