- Organocatalyzed [2+2] Cycloaddition Reactions between Quinone Imine Ketals and Allenoates
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A new cycloaddition reaction of quinone imine ketals (QIKs), which could be utilized to the construction of functionalized azaspirocyclics under mild conditions, is described. This transformation involved a [2+2] cycloaddition reaction between QIKs and allenoates catalyzed by DABCO, and then treatment with 1 N HCl in one-pot. The strategy could provide a practical route to access azetidine-fused spirohexadienones in good to excellent yields and with high E -selectivity.
- Liu, Teng,He, Chixian,Wang, Fan,Shen, Xiang,Li, Yongqin,Lang, Man,Li, Guijun,Huang, Chao,Cheng, Feixiang
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p. 518 - 526
(2020/10/12)
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- 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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p. 8917 - 8920
(2021/09/10)
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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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- Substituted dienes prepared from betulinic acid – Synthesis, cytotoxicity, mechanism of action, and pharmacological parameters
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A set of new substituted dienes were synthesized from betulinic acid by its oxidation to 30-oxobetulinic acid followed by the Wittig reaction. Cytotoxicity of all compounds was tested in vitro in eight cancer cell lines and two noncancer fibroblasts. Almost all dienes were more cytotoxic than betulinic acid. Compounds 4.22, 4.30, 4.33, 4.39 had IC50 below 5 μmol/L; 4.22 and 4.39 were selected for studies of the mechanism of action. Cell cycle analysis revealed an increase in the number of apoptotic cells at 5 × IC50 concentration, where activation of irreversible changes leading to cell death can be expected. Both 4.22 and 4.39 led to the accumulation of cells in the G0/G1 phase with partial inhibition of DNA/RNA synthesis at 1 × IC50 and almost complete inhibition at 5 × IC50. Interestingly, compound 4.39 at 5 × IC50 caused the accumulation of cells in the S phase. Higher concentrations of tested drugs probably inhibit more off-targets than lower concentrations. Mechanisms disrupting cellular metabolism can induce the accumulation of cells in the S phase. Both compounds 4.22 and 4.39 trigger selective apoptosis in cancer cells via intrinsic pathway, which we have demonstrated by changes in the expression of the crucial apoptosis-related protein. Pharmacological parameters of derivative 4.22 were superior to 4.39, therefore 4.22 was the finally selected candidate for the development of anticancer drug.
- Frydrych, Ivo,Urban, Milan,?arek, Jan,Benická, Sandra,D?ubák, Petr,Gurská, Soňa,Hajdúch, Marián,Kotulová, Jana,Li?ková, Barbora,Olejníková, Denisa,Pokorny, Jan
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- TREATMENT OF DISORDERS ASSOCIATED WITH OXIDATIVE STRESS AND COMPOUNDS FOR SAME
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The present invention relates to the treatment of disorders associated with oxidative stress including neuropathic pain and small synthetically derived compounds for treating such disorders.
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-
Page/Page column 51-52
(2021/09/17)
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- Catalytic Synthesis of 1 H-2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers
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The metallo-radical activation of ortho-allylcarbonyl-aryl N-arylsulfonylhydrazones with the paramagnetic cobalt(II) porphyrin catalyst [CoII(TPP)] (TPP = tetraphenylporphyrin) provides an efficient and powerful method for the synthesis of novel 8-membered heterocyclic enol ethers. The synthetic protocol is versatile and practical and enables the synthesis of a wide range of unique 1H-2-benzoxocins in high yields. The catalytic cyclization reactions proceed with excellent chemoselectivities, have a high functional group tolerance, and provide several opportunities for the synthesis of new bioactive compounds. The reactions are shown to proceed via cobalt(III)-carbene radical intermediates, which are involved in intramolecular hydrogen transfer (HAT) from the allylic position to the carbene radical, followed by a near-barrierless radical rebound step in the coordination sphere of cobalt. The proposed mechanism is supported by experimental observations, density functional theory (DFT) calculations, and spin trapping experiments.
- De Bruin, Bas,De Zwart, Felix J.,Li, Zirui,Mathew, Simon,Wolzak, Lukas A.,Zhou, Minghui
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supporting information
p. 20501 - 20512
(2021/12/03)
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- Enantioselective Allenoate-Claisen Rearrangement Using Chiral Phosphate Catalysts
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Herein we report the first highly enantioselective allenoate-Claisen rearrangement using doubly axially chiral phosphate sodium salts as catalysts. This synthetic method provides access to β-amino acid derivatives with vicinal stereocenters in up to 95percent ee. We also investigated the mechanism of enantioinduction by transition state (TS) computations with DFT as well as statistical modeling of the relationship between selectivity and the molecular features of both the catalyst and substrate. The mutual interactions of charge-separated regions in both the zwitterionic intermediate generated by reaction of an amine to the allenoate and the Na+-salt of the chiral phosphate leads to an orientation of the TS in the catalytic pocket that maximizes favorable noncovalent interactions. Crucial arene-arene interactions at the periphery of the catalyst lead to a differentiation of the TS diastereomers. These interactions were interrogated using DFT calculations and validated through statistical modeling of parameters describing noncovalent interactions.
- Ellwart, Mario,Gensch, Tobias,Han, Seo-Jung,Lin, Hsin-Hui,Miró, Javier,Sigman, Matthew S.,Toste, F. Dean
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supporting information
p. 6390 - 6399
(2020/04/27)
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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
-
supporting information
p. 1885 - 1890
(2019/06/21)
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- Heavier Carbonyl Olefination: The Sila-Wittig Reaction
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The Wittig reaction is one of the most versatile tools in the repertoire of organic chemists. Thus, a broad variety of carbonyl compounds can be converted to tailor-made alkenes with phosphorus ylides under mild conditions. However, no comparable reaction has been reported for silanones, the silicon congeners of ketones. Here, we demonstrate for the first time the successful application of the Wittig olefination to iminosilylsilanone 1. The selective formation of a series of silenes (R2Sia? CR2) via the sila-Wittig reaction revealed an unprecedented approach to otherwise elusive compounds. In addition, the highly reactive and zwitterionic nature of 1 was also susceptible to nucleophilic attacks and cycloaddition reactions by and with the phosphorus ylides. Our results therefore make another important contribution to discovering the differences and similarities between carbon and silicon.
- Reiter, Dominik,Frisch, Philipp,Szilvási, Tibor,Inoue, Shigeyoshi
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supporting information
p. 16991 - 16996
(2019/10/16)
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- Intermolecular Dehydrative Coupling and Intramolecular Cyclization of Ruthenium Vinylidene Complexes Formed from Aromatic Propynes Containing Carbonyl Functionalities
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A remarkable intermolecular dehydrative coupling reaction with the formation of a C?C bond was found for the vinylidene complex 2 a, yielding the dinuclear bisvinylidene complex 4 a. Complex 2 a containing 1-hydroxyindan moiety was first formed from the reaction of o-propynyl benzaldehyde 1 a with [Ru]–Cl ([Ru]=Cp(PPh3)2Ru) by a cyclization process. For analogous aldehyde 1 b containing an additional 1,3-dioxolane group on the aryl ring, similar intermolecular coupling yields the dinuclear bisvinylidene complex 4 b. However, the fluoro group on the aryl ring in aldehyde 1 c inhibits the coupling reaction, giving only the vinylidene complex 2 c. For the reactions of [Ru]–Cl in MeOH with compounds 1 f, 1 g and 1 h, each with a ketone functionality, cyclization gives vinylidene complexes 2 f, 2 g and 2 h, respectively. However, no similar intermolecular coupling was observed, instead, the intramolecular dehydration yields 8 f, 8 g and 8 h, respectively. In CDCl3, catalytic cyclization is observed for the o-propynylphenyl ketone 1 h with [Ru]–Cl at 50 °C giving the isochromene products 14 h. Furthermore, treatment of the o-propynylaryl α,β-unsaturated ketones 1 k–m and 1 n with [Ru]–Cl in MeOH affords the corresponding vinylidene complexes 10 k–m and 11 n each with 1-benzosuberone moiety in the presence of NH4PF6. These intramolecular cyclization products were formed by the addition of Cβ onto the terminal carbon of the alkene moiety. All these reaction products were characterized by spectroscopic methods. In addition, structures of complexes 4 a, and 10 l were confirmed by single crystal X-ray diffraction analysis.
- Chia, Pi-Yeh,Kuo, Cheng-Chen,Huang, Shou-Ling,Liu, Yi-Hong,Liu, Ling-Kang,Lin, Ying-Chih
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supporting information
p. 3885 - 3894
(2018/11/10)
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- Electrochemical Dimerization of Phenylpropenoids and the Surprising Antioxidant Activity of the Resultant Quinone Methide Dimers
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A simple method for the dimerization of phenylpropenoid derivatives is reported. It leverages electrochemical oxidation of p-unsaturated phenols to access the dimeric materials in a biomimetic fashion. The mild nature of the transformation provides excellent functional group tolerance, resulting in a unified approach for the synthesis of a range of natural products and related analogues with excellent regiocontrol. The operational simplicity of the method allows for greater efficiency in the synthesis of complex natural products. Interestingly, the quinone methide dimer intermediates are potent radical-trapping antioxidants; more so than the phenols from which they are derived—or transformed to—despite the fact that they do not possess a labile H-atom for transfer to the peroxyl radicals that propagate autoxidation.
- Romero, Kevin J.,Galliher, Matthew S.,Raycroft, Mark A. R.,Chauvin, Jean-Philippe R.,Bosque, Irene,Pratt, Derek A.,Stephenson, Corey R. J.
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supporting information
p. 17125 - 17129
(2018/12/04)
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- Wittig Ylide Mediated Decomposition of N -Sulfonylhydrazones to Sulfinates
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N-Sulfonylhydrazones generate sulfinates selectively when treated with a stabilized Wittig ylide in a polar aprotic solvent at elevated temperature. The transition metal and base free decomposition method is applicable to N-sulfonylhydrazones generated from a number of aromatic and heteroaromatic aldehydes and ketones. In the case of N-tosylhydrazones derived from O-allyl and O-propargyl salicylaldehydes, selective formation of sulfinate occurs over intramolecular [3 + 2]-cycloaddition reaction.
- Choudhary, Deepika,Khatri, Vineeta,Basak, Ashok K.
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supporting information
p. 1703 - 1706
(2018/04/14)
-
- Nickel-catalyzed, ligand-free, diastereoselective synthesis of 3-methyleneindan-1-ols
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Nickel-catalyzed, highly diastereoselective annulations between activated allenes and 2-acetylarylboronic acid or 2-formylarylboronic acids are reported. No ligand for nickel is required, and the reactions proceed efficiently at room temperature to give a broad range of substituted 3-methyleneindan-1-ols. Preliminary results of an enantioselective variant are also described.
- Panchal, Heena,Clarke, Christopher,Bell, Charles,Karad, Somnath Narayan,Lewis, William,Lam, Hon Wai
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supporting information
p. 12389 - 12392
(2018/11/20)
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- Biocatalytic access to nonracemic γ-oxo esters: Via stereoselective reduction using ene-reductases
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The asymmetric bioreduction of α,β-unsaturated γ-keto esters using ene-reductases from the Old Yellow Enzyme family proceeds with excellent stereoselectivity and high conversion levels, covering a broad range of acyclic and cyclic derivatives. Various strategies were employed to provide access to both enantiomers, which are versatile precursors of bioactive molecules. The regioselectivity of hydride addition on di-activated alkenes was elucidated by isotopic labeling experiments and showed strong preference for the keto moiety as activating/binding group as opposed to the ester. Finally, chemoenzymatic synthesis of (R)-2-(2-oxocyclohexyl)acetic acid was achieved in high ee on a preparative scale combining enzymatic reduction followed by ester hydrogenolysis.
- Turrini, Nikolaus G.,Cioc, Rǎzvan C.,Van Der Niet, Daan J. H.,Ruijter, Eelco,Orru, Romano V. A.,Hall, Mélanie,Faber, Kurt
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supporting information
p. 511 - 518
(2017/08/14)
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- Phosphine-Catalyzed Domino β/γ-Additions of Benzofuranones with Allenoates: A Method for Unsymmetrical 3,3-Disubstituted Benzofuranones
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A phosphine-catalyzed domino process of benzofuranones with allenoates has been developed which furnishes highly functionalized unsymmetrical 3,3-disubstituted benzofuranones in synthetically useful yields. The mechanism for the transformation is a tandem β-umpolung/γ-umpolung process.
- Huang, Zhusheng,Yang, Xiuqin,Yang, Fulai,Lu, Tao,Zhou, Qingfa
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supporting information
p. 3524 - 3527
(2017/07/17)
-
- Stereoselective Synthesis of the C1-C9 and C11-C25 Fragments of Amphidinolides C, C2, C3, and F
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An efficient synthesis of the C1-C9 and the C11-C25 fragments of amphidinolides C, C2, C3, and F from a common intermediate is reported. The construction of the C1-C9 fragment involves an intramolecular hetero-Michael cyclization to form the 3,5-disubstituted trans-tetrahydrofuran moiety. The approach to prepare the C11-C25 fragment utilizes a highly stereoselective aerobic cobalt-catalyzed alkenol cyclization and a chelated Mukaiyama aldol reaction to form the C13-C14 bond and to concomitantly install the C13 hydroxyl group.
- Akwaboah, Daniel C.,Wu, Dimao,Forsyth, Craig J.
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supporting information
p. 1180 - 1183
(2017/03/14)
-
- Photoinduced Intermolecular [4+2] Cycloaddition Reaction for Construction of Benzobicyclo[2.2.2]octane Skeletons
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A novel and efficient method for the synthesis of highly substituted benzobicyclo[2.2.2]octane skeletons has been explored. Under UV-light irradiation, o-divinylbenzenes underwent a pericyclic reaction to form the cyclic o-quinodimethane intermediates which were subsequently reacted with olefins through [4+2] addition to construct the benzobicyclo[2.2.2]octane skeletons in mild conditions. Gram scale reactions demonstrated the synthetic potential application of this protocol.
- Liu, Qiang,Wang, Junlei,Li, Dazhi,Yang, Chao,Xia, Wujiong
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p. 1389 - 1402
(2017/02/10)
-
- Mechanochemical enzymatic resolution of N-benzylated-β3-amino esters
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The use of mechanochemistry to carry out enantioselective reactions has been explored in the last ten years with excellent results. Several chiral organocatalysts and even enzymes have proved to be resistant to milling conditions, which allows for rather efficient enantioselective transformations under ball-milling conditions. The present article reports the first example of a liquid-assisted grinding (LAG) mechanochemical enzymatic resolution of racemic β3-amino esters employing Candida antarctica lipase B (CALB) to afford highly valuable enantioenriched N-benzylated-β3-amino acids in good yields. Furthermore the present protocol is readily scalable.
- Pérez-Venegas, Mario,Reyes-Rangel, Gloria,Neri, Adrián,Escalante, Jaime,Juaristi, Eusebio
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supporting information
p. 1728 - 1734
(2017/09/27)
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- Iron(II) N-heterocyclic carbene complexes in catalytic one-pot Wittig reactions: Mechanistic insights
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An iron(II) N-heterocyclic carbene (NHC) complex is applied as catalyst for aldehyde olefination with ethyl diazoacetate (EDA) in the presence of triphenylphosphine. The reaction leads to high olefin yields with very good E-selectivities. The key step of the reaction is the catalytic in situ generation of a phosphorus ylide. Mechanistic studies reveal two possible pathways for the formation of the Wittig reagent with respect to the carbene source being the metal carbene (NHC)FeIV[dbnd]CH(CO2Et), and phosphazine, Ph3P[dbnd]N[sbnd]N[dbnd]CH(CO2Et). Based on the experimental observations a new mechanism for the transformation of phosphazine is proposed.
- Karaca, ?zden,Anneser, Markus R.,Kück, Jens W.,Lindhorst, Anja C.,Cokoja, Mirza,Kühn, Fritz E.
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p. 213 - 220
(2016/10/25)
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- BTK inhibitor and uses thereof
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The present invention provides a BTK inhibitor compound (having s structure represented by a formula (I)) and uses of the BTK inhibitor compound in medicines. According to the present invention, the compound and the pharmaceutical composition can be used for treatment of diffuse large B-cell lymphoma, follicular lymphoma or chronic lymphocytic leukemia. The formula (I) is defined in the specification.
- -
-
Paragraph 0199-0200
(2017/01/09)
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- Intramolecular 10,10a-[2+2] photocycloaddition reactions of phenanthrenes with linked styrene
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Intramolecular photocycloaddition reactions of styrene linked 9-cyanophenanthrenes led to formation of C-9 C-10 [2+2] cycloadducts which underwent cycloreversion under the prolonged irradiation conditions to regenerate the starting substrates. Unusual 8-membered ring products were irreversibly formed in these processes. Product distributions were governed by substituent controlled, donor-acceptor interactions that direct generation of two intramolecular singlet exciplexes, which serve as intermediates in the pathways to formation of 9,10- and 10,10a-[2+2] adducts.
- Maeda, Hajime,Nakashima, Ryota,Sugimoto, Akira,Mizuno, Kazuhiko
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p. 232 - 237
(2016/07/21)
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- Spirastrellolide E: Synthesis of an advanced C(1)-C(24) southern hemisphere
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The synthesis of a C(1)-C(24) advanced southern hemisphere fragment towards the total synthesis of spirastrellolide E has been achieved. Highlights of the route include a highly convergent Type I Anion Relay Chemistry (ARC) tactic for fragment assembly, in conjunction with a directed, regioselective gold-catalyzed alkyne functionalization to generate the central unsaturated [6,6]-spiroketal.
- Sokolsky, Alexander,Wang, Xiaozhao,Smith, Amos B.
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supporting information
p. 3160 - 3164
(2015/03/04)
-
- Asymmetric aldol reaction of allenoates: Regulation for the selective formation of isomeric allenyl or alkynyl aldol adduct
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A highly stereoselective synthesis of 3-butynyl-threo-aldol adducts is achieved from the reaction of allyl allenoate with a chiral bromoborane in the presence of iPr2NEt, followed by addition of BF3·OEt2 as an additive to
- Bang, Jiyun,Kim, Hyuna,Kim, Jihyun,Yu, Chan-Mo
-
supporting information
p. 1573 - 1576
(2015/03/30)
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- Titania-promoted carboxylic acid alkylations of alkenes and cascade addition-cyclizations
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Photochemical reactions employing TiO2 and carboxylic acids under dry anaerobic conditions led to several types of C-C bond-forming processes with electron-deficient alkenes. The efficiency of alkylation varied appreciably with substituents in the carboxylic acids. The reactions of aryloxyacetic acids with maleimides resulted in a cascade process in which a pyrrolochromene derivative accompanied the alkylated succinimide. The selectivity for one or other of these products could be tuned to some extent by employing the photoredox catalyst under different conditions. Aryloxyacetic acids adapted for intramolecular ring closures by inclusion of 2-alkenyl, 2-aryl, or 2-oximinyl functionality reacted rather poorly. Profiles of reactant consumption and product formation for these systems were obtained by an in situ NMR monitoring technique. An array of different catalyst forms were tested for efficiency and ease of use. The proposed mechanism, involving hole capture at the TiO2 surface by the carboxylates followed by CO2 loss, was supported by EPR spectroscopic evidence of the intermediates. Deuterium labeling indicated that the titania likely donates protons from surface hydroxyl groups as well as supplying electrons and holes, thus acting as both a catalyst and a reaction partner.
- Manley, David W.,McBurney, Roy T.,Miller, Phillip,Walton, John C.,Mills, Andrew,O'Rourke, Christopher
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p. 1386 - 1398
(2014/03/21)
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- Synthesis of labdane diterpenes galanal A and B from (+)-sclareolide
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The first chemical synthesis of galanal A and B was achieved by a concise and highly efficient pathway starting from commercially available (+)-sclareolide and features a Wittig reaction and a titanocene-mediated radical cyclization as the key steps.
- Kumar, Chebolu Naga Sesha Sai Pavan,Chein, Rong-Jie
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supporting information
p. 2990 - 2992
(2014/06/23)
-
- Selective synthesis and comparative activity of olefinic isomers of 1,2-benzothiazine-1,1-dioxide carboxylates as aldose reductase inhibitors
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α,β- and β,γ-unsaturated carboxylate isomers of 1,2-benzothiazine-1,1-dioxide were selectively synthesized via the Wittig olefination reaction under various temperature conditions. At 40 °C, α,β-unsaturated esters with high Z-stereoselectivity (83-87%) we
- Parveen, Shagufta,Hussain, Saghir,Zhu, Shaojuan,Qin, Xiangyu,Hao, Xin,Zhang, Shuzhen,Lu, Jianglu,Zhu, Changjin
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p. 21134 - 21140
(2014/06/09)
-
- Synthesis of 1,4-enamino ketones by [3,3]-rearrangements of dialkenylhydroxylamines
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The synthesis of 1,4-enamino ketones has been achieved through the [3,3]-rearrangement of dialkenylhydroxylamines generated from the addition of N-alkenylnitrones to electron-deficient allenes. The mild conditions required for this reaction, and the simultaneous installation of a fluorenyl imine N-protecting group as a consequence of the rearrangement, avoid spontaneous cyclization of the 1,4-enamino ketones to form the corresponding pyrroles and allow for the isolation and controlled divergent functionalization of these reactive intermediates. The optimization, scope, and tolerance of the new method are discussed with demonstrations of the utility of the products for the synthesis of pyrroles, 1,4-diones, and furans.
- Pecak, Wiktoria H.,Son, Jongwoo,Burnstine, Amy J.,Anderson, Laura L.
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supporting information
p. 3440 - 3443
(2014/07/21)
-
- Grubbs cross-metathesis pathway for a scalable synthesis of γ-keto-α,β-unsaturated esters
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A direct and scalable route to γ-keto-α,β-unsaturated esters, useful intermediates in medicinal chemistry and natural products synthesis, is reported. The key step involves the use of Grubbs' second-generation olefin metathesis catalyst for cross-metathes
- Nair, Reji N.,Bannister, Thomas D.
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p. 1467 - 1472
(2014/03/21)
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- Copper-catalyzed asymmetric synthesis and comparative aldose reductase inhibition activity of (+)/(-)-1,2-benzothiazine-1,1-dioxide acetic acid derivatives
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A copper catalyst system for the asymmetric 1,4-hydrosilylation of the α,β-unsaturated carboxylate class was developed by which synthesis of (+)- and (-)-enantiomers of 1,2-benzothiazine-1,1-dioxide acetates has been achieved with a good yield and an excellent level of enantioselectivity. A comparative structure-activity relationship study yielded the following order of aldose reductase inhibition activity: (-)-enantiomers > racemic > (+)-enantiomers. Further, a molecular docking study suggested that the (-)-enantiomer had significant binding affinity and thus increased inhibition activity.
- Parveen, Shagufta,Hussain, Saghir,Qin, Xiangyu,Hao, Xin,Zhu, Shaojuan,Rui, Miao,Zhang, Shuzhen,Fu, Fengyan,Ma, Bing,Yu, Qun,Zhu, Changjin
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p. 4963 - 4972
(2014/06/23)
-
- Catalytic enantioselective carboannulation with allylsilanes
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The first catalytic asymmetric carboannulation with allylsilanes is presented. The enantioselective [3+2] annulation is catalyzed using a scandium(III)/indapybox complex with tetrakis-[3,5-bis(trifluoromethyl)phenyl]- borate (BArF) to enhance catalytic activity and control stereoselectivity. Functionalized cyclopentanes containing a quaternary carbon center are derived from alkylidene oxindole, coumarin, and malonate substrates with high stereoselectivity. The enantioselective 1,4-conjugate addition and enantioselective lactone formation (by trapping of the β-silyl carbocation) is also described. It's a trap: The catalytic asymmetric carboannulation of alkylidene oxindole, coumarin, and malonate substrates with allylsilanes in the presence of a ScIII/BArF/indapybox catalyst affords functionalized cyclopentanes containing a quaternary carbon center with high stereoselectivity. Enantioselective allylation and asymmetric lactone formation by trapping of the β-silyl carbocation are also presented.
- Ball-Jones, Nicolas R.,Badillo, Joseph J.,Tran, Ngon T.,Franz, Annaliese K.
-
supporting information
p. 9462 - 9465
(2015/02/05)
-
- Catalytic asymmetric cross-dehydrogenative coupling: Activation of C-H bonds by a cooperative bimetallic catalyst system
-
A cooperative bimetallic catalyst system was applied in the catalytic asymmetric cross-dehydrogenative coupling of β-ketoesters and xanthene. Various optically active xanthene derivatives bearing a quaternary stereogenic carbon center were obtained in moderate to good yields (up to 90%) with excellent enantioselectivities (up to 99% ee). Meanwhile, a transition-state model was proposed to explain the origin of the asymmetric induction.
- Cao, Weidi,Liu, Xiaohua,Peng, Ruixue,He, Peng,Lin, Lili,Feng, Xiaoming
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supporting information
p. 3470 - 3472
(2013/05/23)
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- Annelated P-containing heterocycles from aryl- and hetaryl-substituted phosphonium iodonium ylides with a methoxycarbonyl-group
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Hetaryl-substituted phosphonium-iodonium ylides with a methoxycarbonyl group as acceptor proved to be highly reactive toward various alkynes in comparison with triphenyl-substituted analogue. We were able to isolate annelated P-containing heterocycles - λ
- Matveeva, Elena D.,Podrugina, Tatyana A.,Taranova, Marina A.,Melikhova, Ekaterina Yu.,Gleiter, Rolf,Zefirov, Nikolay S.
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p. 7395 - 7402
(2013/08/23)
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- An approach to the carbon backbone of bielschowskysin, part 1: Photocyclization strategy
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Several macrocyclization reaction attempts of highly advanced precursors toward a total synthesis of marine diterpene bielschowskysin are disclosed. Biomimetic [2+2]-photocyclization reactions were applied to construct the cyclobutane core in these intermediates, which could be accessed along scalable high-yielding reaction sequences from cheap enantiopure starting-materials. Asymmetric syntheses of various highly functionalized intermediates toward the total synthesis of bielschowskysin (1) are described. In particular a biomimetic [2+2]-photocycloaddition reaction strategy, forming the cyclobutane core, was followed by various macrocyclization reactions attempts. Copyright
- Himmelbauer, Martin,Farcet, Jean-Baptiste,Gagnepain, Julien,Mulzer, Johann
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p. 8214 - 8244
(2014/01/06)
-
- Cicindeloine from Stenus cicindeloides-isolation, structure elucidation, and total synthesis
-
The new piperideine alkaloid cicindeloine (3) was isolated from the pygidial glands of the beetles Stenus cicindeloides and Stenus solutus. The structure and absolute configuration of 3 were elucidated by NMR spectroscopy and asymmetric synthesis, respect
- Mueller, Tobias,Goehl, Matthias,Lusebrink, Inka,Dettner, Konrad,Seifert, Karlheinz
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experimental part
p. 2323 - 2330
(2012/05/31)
-
- METHOD FOR OBTAINING CINATRINS C3 AND C1
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The present invention relates to a process for obtaining cinatrins C1 and C3 and derivatives thereof which comprises the hydroxylation of a compound of formula (III). The invention also relates to the intermediates of said synthesis
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-
Page/Page column 15-16
(2011/04/14)
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- 1,2-Benzothiazine 1,1-dioxide carboxylate derivatives as novel potent inhibitors of aldose reductase
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Due to the importance of aldose reductase (ALR2) as a potential drug target in the treatment of diabetic complications, there are increasing interests in design and synthesis of ALR2 inhibitors. Here, we prepared 1,2-benzothiazine 1,1-dioxide acetic acid derivatives and investigated their inhibition activity. Most of these derivatives were found to be active with IC50 values ranging from 0.11 μM to 10.42 μM, and compound 8d, 2-[2-(4-bromo-2- fluorobenzyl)-1,1-dioxido-2H-1,2-benzothiazin-4(3H)-ylidene]acetic acid, showed the most potent inhibition activity. Further, SAR and docking studies suggest that in comparison with the α,β-unsaturated derivatives, the saturated carboxylic acid derivatives had a greater binding affinity with the enzyme and thus an enhanced inhibition activity. Therefore, development of more powerful ARIs based on benzothiazine 1,1-dioxide by stereo-controlled synthesis could be expected.
- Chen, Xin,Zhang, Shuzhen,Yang, Yanchun,Hussain, Saghir,He, Minlan,Gui, Dequan,Ma, Bing,Jing, Chaojun,Qiao, Zhixin,Zhu, Changjin,Yu, Qun
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experimental part
p. 7262 - 7269
(2012/01/03)
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- Stereoselective olefination of N-sulfonyl imines with stabilized phosphonium ylides for the synthesis of electron-deficient alkenes
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An unprecedented protocol has been developed for thestereoselective synthesis of structurally diverse electron-deficient alkenes in moderate to excellent yields from readily accessible N-sulfonyl imines and stabilized phosphonium ylides. Significantly, the olefination reaction of N-sulfonylimines with nitrile-stabilized phosphonium ylides affords an array of α,β-unsaturated nitriles with high Z selectivity, and the reactions with ester-, amide-, and ketone-stabilized phosphonium ylides afford α,β-unsaturated esters, amides, and ketones with high E selectivity, respectively. Spectroscopic analysis of the reaction mixtures and trapping of the intermediates allow plausible mechanisms to be proposed. Initialimine/ylide addition leads to the formation of betaines that cyclize to form 1,2-azaphosphetanes that subsequently eliminate iminophosphoranes to yield alkenes. For the synthesis of electron-deficient 1,2-disubstituted alkenes, the presence of an electron-withdrawing group in the betaine allows rapid interconversion between its two diastereomers through proton transfer. The Z/E selectivity for alkene synthesis is determined by the different rates at which the two betaine diastereomers form the corresponding 1,2-azaphosphetane diastereomers. In contrast, the Z/E selectivity for the synthesis of electron-deficient trisubstituted alkenes originates from the diastereoselective addition of stabilized phosphonium ylides to N-sulfonyl imines.
- Fang, Fan,Li, Yuan,Tian, Shi-Kai
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supporting information; experimental part
p. 1084 - 1091
(2011/04/15)
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- Asymmetrie hydrogenation of α,ss-unsaturated esterphosphonates
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The rhodium-catalyzed asymmetric hydrogenation of readily available α,ss-unsaturated esterphosphonates affords the corresponding α-chiral phosphonates in excellent yield and ee. The resulting products are useful multifunctional building blocks applied in
- Huang, Yange,Berthiol, Florian,Stegink, Bart,Pollard, Michael M.,Minnaard, Adriaan J.
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experimental part
p. 1423 - 1430
(2009/12/24)
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- Phosphonium-iodonim ylides in nucleophilic substitution reactions
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Properties of mixed phosphonium-iodonium ylides were investigated, and the compounds were shown to be capable to behave as O-nucleophiles in nucleophilic substitution reactions.
- Matveeva,Podrugina,Grishin,Pavlova,Zefirov
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p. 201 - 206
(2007/10/03)
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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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- Fluorine segregation in crystalline materials: Structural control and solid-state [2+2] cycloaddition in CF3-substituted tetrathiafulvalene derivatives
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The well-known influence of long perfluorinated chains on the structures and stability of amphiphilic molecules in liquid crystalline mesophases or mesoscopic micellar arrangements is evaluated here in the realm of crystalline materials based on rigid aro
- Jeannin, Olivier,Fourmigue, Marc
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p. 2994 - 3005
(2008/09/16)
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- Cytotoxic agents and methods of use
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Disclosed are compounds that inhibit proteasomic activity in cells. Also disclosed are pharmaceutical compositions comprising such compounds as well as methods to treat conditions, particularly cell proliferative conditions, such as cancer and inflammator
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Page/Page column 19
(2010/02/14)
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- Synthesis and spectroscopic characterization of 1-13C- and 4-13C-plastoquinone-9
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This paper presents the synthesis of 1-13C- and 4-13C-plastoquinone-9 and their characterization with NMR spectroscopy and mass spectrometry. The synthetic scheme has been further adapted to introduce 13C-labeled plastoquinones on all individual and on each combination of positions in the quinone ring. Also a two-step scheme is disclosed to prepare unlabeled plastoquinone-9. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Boers, Rutger B.,Randulfe, Yolanda Pazos,Van Der Haas, Hendrikus N. S.,Van Rossum-Baan, Marleen,Lugtenburg, Johan
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p. 2094 - 2108
(2007/10/03)
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- Specific isotope enrichment of methyl methacrylate
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A synthetic scheme has been developed to prepare methyl methacrylate specifically 13C-labelled at all different positions and in any combination of positions, from simple, commercially available starting materials. According to this scheme methyl (1-13C) and methyl (2-13C)methacrylate (1a and 1b) have been prepared with high label incorporation (99%).
- Werkhoven, Thekla M.,Van Nispen, Reinier,Lugtenburg, Johan
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p. 2909 - 2914
(2007/10/03)
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- Tandem Conjugate addition of Silylcuprate and Benzenesulfenyl Chloride to Unsaturated Esters: Stereoselective Preparation of anti-3-Dimethylphenylsilyl-2-phenylthio Aldehydes
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Conjugate addition of dimethylphenylsilylcuprate is successful even to a 2,3-disubstituted acrylate ester and when followed by α-sulfenylation of the trapped silyl enol ether intermediate, reduction and re-oxidation gives, for example, (2SR,3RS)-(anti)-2,
- Villa, Maria-Jesus,Warren, Stuart
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p. 1569 - 1572
(2007/10/02)
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- Stepwise mechanisms in the ene reaction of α,β-unsaturated esters with N-phenyl-l,2,4-triazoline-3,5-dione and Singlet oxygen. Intermolecular primary and secondary hydrogen isotope effects
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Intermolecular primary and secondary isotope effects on the ene reaction of N-phenyl-l,2,4-triazoline-3,5-dione (PTAD) and singlet oxygen (1O2) with deuterium-substituted (E)-2-methylbuten-2-oic (tiglic) acid methyl esters have been determined. In the case of 1O2, the primary isotope effect is 1.30-1.49 and the α and β secondary isotope effects are near unity, consistent with a stepwise reaction path via a perepoxide intermediate, where the allylic hydrogen-abstraction step is rate determining. On the other hand, the existence of both primary (1.44) and inverse α and β secondary isotope effects (0.91 and 0.77, respectively) in the PTAD reaction is consistent with either a concerted or a stepwise mechanism. Experiments in which both intermolecular primary and secondary isotope effects were measured at the same time suggest that, like singlet oxygen, PTAD reacts in a stepwise manner with the formation of the aziridinium imide interme diate (AI) in the rate-determining-step.
- Elemes, Yiannis,Foote, Christopher S.
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p. 6044 - 6050
(2007/10/02)
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- Preparation and Characterisation of Some New Bisphosphonium Ylides and Their Palladium(II) and Mercury(II) Complexes
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Transylidation of alkylenetriphenylphosphoranes with bisthioesters of dicarboxylic acids affords new bisphosphonium ylides of the type (n=0, 2).These ylides behave as chelating ligands and form 1:1 adducts with Pd(II) and Hg(II) chlorides in which the metal appears to be coordinated through the ylidic carbon atom.
- Sanehi, Ram,Bansal, R. K.,Mehrotra, R. C.
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p. 398 - 402
(2007/10/02)
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- Pesticides
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New insecticides are of formula: STR1 wherein R1 represents hydrogen or a methyl group; R2 represents hydrogen or a halogeno or lower alkyl group; R3 represents hydrogen or a halogeno or carbo(lower alkoxy) group which contains at least 2 carbon atoms in the lower alkoxy residue when R2 represents methyl; with the proviso that (a) R2 and R3 each represent hydrogen only when R1 represents methyl, (b) when R1 and R3 each represent hydrogen and R2 represents alkyl, that alkyl group contains at least 2 carbon atoms and (c) when R3 represents halogeno, R2 represents hydrogen or halogeno; and R represents a group which forms insecticidal esters with chrysanthemic acid e.g. 5-benzyl-3-furylmethyl, 3-phenoxybenzyl, α-cyano-3-phenoxybenzyl. The esters are prepared by forming the ester linkage conventionally or by a Wittig reaction using a 3-formyl- or 3-acetyl-2,2-dimethyl cyclopropane carboxylic acid esterified with the desired residue or by an alkyl group which is subsequently converted to the desired residue.
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