- Substituent Effect Induces Emission Modulation of Stilbene Photoswitches by Spatial Tuning of the N/B Electronic Constraints
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We present a family of stilbene derivatives (1-4) ortho-functionalized with an electron donor and acceptor. Their emission was tuned by donor substitutions, dictating charge transfer dependent on the N···B spatial separation. The steric reduction of subst
- Chen, Pangkuan,Ji, Guangqian,Wang, Nan,Yin, Xiaodong
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Read Online
- CYCLOBUTYL AMIDE MONOACYLGLYCEROL LIPASE MODULATORS
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Compounds of Formula (I), and pharmaceutically acceptable salts, isotopes, N-oxides, solvates, and stereoisomers thereof, pharmaceutical compositions containing them, methods of making them, and methods of using them including methods for treating disease states, disorders, and conditions associated with MGL modulation, such as those associated with pain, psychiatric disorders, neurological disorders (including, but not limited to depression, major depressive disorder, treatment resistant depression, anxious depression, autism spectrum disorders, Asperger syndrome, and bipolar disorder), cancers and eye conditions: wherein R1, , R3, and L are as defined herein.
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Paragraph 0277; 0326; 0327; 0338; 0339
(2022/03/31)
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- Functionalized Cyclopropanes as Versatile Intermediates for the Diversity-Oriented Synthesis of γ-Lactones, γ-Lactams and δ-Lactams
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A two-step procedure for the preparation of cyclopropanecarboxaldehyde-1,1-diester from a γ,δ-epoxyester and its synthetic versatility are described herein. The epoxide ring-opening/cyclopropanation process occurs in the presence of Mg(ClO 4) 2under heating, resulting in cyclopropanemethanol-1,1-diester in 65% yield. A mild TEMPO-mediated oxidation of this substrate readily generated the corresponding aldehyde in 75% yield, which was applied in the one-pot synthesis of four cyclopropylidene-γ-lactams and three δ-lactams. In addition, vinylcyclopropanes were obtained through the Wittig reaction of the aldehyde with phosphonium salts and used as precursors for tetrahydrofurans.
- Maximiano, Adrielle P.,Ramos, Giovana S.,Marques, Marcelo V.,Sá, Marcus M.
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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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- Catalytic Asymmetric Synthesis of Atropisomeric Quinolines through the Friedl?nder Reaction
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A phosphoric acid catalyzed atroposelective Friedl?nder reaction was developed in which acetylacetone and a variety of 2′-substituted 2-Aminobenzophenones were successfully employed to give optically active biaryl quinolines in good yields and with high enantioselectivities.
- Hu, Xingena,Jiang, Jun,Lan, Yunjun,Li, Juan,Li, Xinhua,Liu, Hongxin,Wan, Junlin,Xiao, Hong-Ping
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supporting information
p. 2198 - 2202
(2019/11/25)
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- Radical Alkyne peri-Annulation Reactions for the Synthesis of Functionalized Phenalenes, Benzanthrenes, and Olympicene
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Radical cyclization reactions at a peri position were used for the synthesis of polyaromatic compounds. Depending on the choice of reaction conditions and substrate, this flexible approach led to Bu3Sn-substituted phenalene, benzanthrene, and olympicene derivatives. Subsequent reactions with electrophiles provided synthetic access to previously inaccessible functionalized polyaromatic compounds.
- Tsvetkov, Nikolay P.,Gonzalez-Rodriguez, Edgar,Hughes, Audrey,dos Passos Gomes, Gabriel,White, Frankie D.,Kuriakose, Febin,Alabugin, Igor V.
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supporting information
p. 3651 - 3655
(2018/03/06)
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- Amine-based compound and organic light-emitting diode including the same
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An amine-based compound is represented by Formula 1: An organic light-emitting diode includes a first electrode, a second electrode, and an organic layer between the first electrode and the second electrode. The organic layer includes an emission layer an
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Page/Page column 91; 93
(2017/07/08)
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- Synthesis and Evaluation of Sterically Demanding Ruthenium Dithiolate Catalysts for Stereoretentive Olefin Metathesis
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Dithiolate ligands have recently been used in ruthenium-catalyzed olefin metathesis and have provided access to a kinetically E selective pathway through stereoretentive olefin metathesis. The typical dithiolate used is relatively simple with low steric demands imparted on the catalyst. We have developed a synthetic route that allows access to sterically demanding dithiolate ligands. The catalysts generated provided a pathway to study the intricate structure-activity relationships in olefin metathesis. It was found that DFT calculations can predict the ligand arrangement around the ruthenium center with remarkable accuracy. These dithiolate catalysts proved resistant to ligand isomerization and were stable even under forcing conditions. Additionally, catalyst initiation and olefin metathesis studies delivered a better understanding to the interplay between dithiolate ligand structure and catalyst activity and selectivity.
- Montgomery, T. Patrick,Grandner, Jessica M.,Houk,Grubbs, Robert H.
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p. 3940 - 3953
(2017/10/31)
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- ALKENES AS ALKYNE EQUIVALENTS IN RADICAL CASCADES TERMINATED BY FRAGMENTATIONS
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Disclosed are methods for rerouting radical cascade cyclizations by using alkenes as alkyne equivalents. The reaction sequence is initiated by a novel 1,2 stannyl shift which achieves chemo- and regioselectivity in the process. The radical “hopping” leads to the formation of the radical center necessary for the sequence of selective cyclizations and fragmentations to follow. In the last step of the cascade, the elimination of a rationally designed radical leaving group via β-C—C bond scission aromatizes the product without the need for external oxidant. The Bu3Sn moiety, which is installed during the reaction sequence, allows further functionalization of the product via facile reactions with electrophiles as well as Stille and Suzuki cross-coupling reactions. This selective radical transformation opens a new approach for the controlled transformation of enynes into extended polycyclic structures of tunable dimensions.
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Paragraph 0212; 0213
(2016/12/22)
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- Compound and organic light emitting device comprising same
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Disclosed are a compound represented by chemical formula 1 and an organic light-emitting device comprising the same. The explanation with respect to a substituent in chemical formula 1 refers to the detailed description. The organic light-emitting device
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Paragraph 0387-0394
(2016/10/07)
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- Novel composite phosphonium salt as well as preparation method and antibacterial application thereof
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The invention belongs to the technical field of fine chemical synthesis and particularly relates to a novel composite phosphonium salt as well as a preparation method and an antibacterial application thereof. The novel composite phosphonium salt adopts a
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Paragraph 0026-0027
(2017/01/26)
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- Benzoquinoline derivative and organoelectroluminescent device employing the same
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The present invention relates to a benzoquinoline derivative, a manufacturing method thereof, and an organic electroluminescent device applying the same. The organic electroluminescent device applying a benzoquinoline derivative of the present invention h
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Paragraph 0111
(2016/11/07)
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- Alkenes as alkyne equivalents in radical cascades terminated by fragmentations: Overcoming stereoelectronic restrictions on ring expansions for the preparation of expanded polyaromatics
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Chemoselective interaction of aromatic enynes with Bu3Sn radicals can be harnessed for selective cascade transformations, yielding either Sn-substituted naphthalenes or Sn-indenes. Depending on the substitution at the alkene terminus, the initial regioselective 5-exo-trig cyclizations can be intercepted at the 5-exo stage via either hydrogen atom abstraction or C-S bond scission or allowed to proceed further to the formal 6-endo products via homoallylic ring expansion. Aromatization of the latter occurs via β-C-C bond scission, which is facilitated by 2c,3e through-bond interactions, a new stereoelectronic effect in radical chemistry. The combination of formal 6-endo-trig cyclization with stereoelectronically optimized fragmentation allows the use of alkenes as synthetic equivalents of alkynes and opens a convenient route to α-Sn-substituted naphthalenes, a unique launching platform for the preparation of extended polyaromatics.
- Mohamed, Rana K.,Mondal, Sayantan,Gold, Brian,Evoniuk, Christopher J.,Banerjee, Tanmay,Hanson, Kenneth,Alabugin, Igor V.
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supporting information
p. 6335 - 6349
(2015/06/02)
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- Coupling cyclizations with fragmentations for the preparation of heteroaromatics: Quinolines from o-alkenyl arylisocyanides and boronic acids
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Stereoelectronic restrictions on homoallylic ring expansion in alkyne cascades can be overcome by using alkenes as synthetic equivalents of alkynes in reaction cascades that are terminated by C-C bond fragmentation. Implementation of this approach using Mn(iii)-mediated reaction of o-alkenyl isocyanides and boronic acids leads to efficient synthesis of substituted quinolines.
- Evoniuk, Christopher J.,Ly, Michelle,Alabugin, Igor V.
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supporting information
p. 12831 - 12834
(2015/08/06)
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- Enantioselective palladium-catalyzed dearomative cyclization for the efficient synthesis of terpenes and steroids
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A novel enantioselective palladium-catalyzed dearomative cyclization has been developed for the efficient construction of a series of chiral phenanthrenone derivatives bearing an all-carbon quaternary center. The effectiveness of this method in the synthe
- Du, Kang,Guo, Pan,Chen, Yuan,Cao, Zhen,Tang, Wenjun,Wang, Zheng
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supporting information
p. 3033 - 3037
(2015/04/14)
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- Diastereoselective Oxidative CN/CO and CN/CN Bond Formation Tandems Initiated by Visible Light: Synthesis of Fused N-Arylindolines
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The synthesis of fused N-arylindolines using visible light photoredox catalysis has been developed. We previously described that photogenerated amine radical cations generate substituted indoles through an intermediate benzylic carbocation. Herein, we expand the application of this chemistry by trapping the benzylic carbocation with tethered heteronucleophiles. The reactivity of the photogenerated benzylic carbocation is explored and applied to a range of substrates with various electronic characters and ring constraints. The method described provides C-2 and C-3 fused indolines bearing a tetrasubstituted carbon stereocenter with greater than 99:1 diastereoselectivity in moderate to good yields.
- Morris, Scott A.,Nguyen, Theresa H.,Zheng, Nan
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supporting information
p. 2311 - 2316
(2015/07/27)
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- Synthesis of 2-phenylnaphthalenes from styryl-2-methoxybenzenes
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A new simple and efficient method for the synthesis of 2-phenylnaphthalenes from electron-rich 1-styryl-2-methoxybenzenes has been described. The reaction proceeds via TFA catalyzed C-C bond cleavage followed by intermolecular [4+2]-Diels-Alder cycloaddition of an in situ formed styrenyl trifluoroacetate intermediate. The quantum chemical calculations identified the transition state for the cycloaddition reaction and helped in tracing the reaction mechanism. The method has been efficiently utilized for synthesis of the phenanthrene skeleton and a naphthalene-based potent and selective ER-β agonist. This journal is
- Mudududdla, Ramesh,Sharma, Rohit,Abbat, Sheenu,Bharatam, Prasad V.,Vishwakarma, Ram A.,Bharate, Sandip B.
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supporting information
p. 12076 - 12079
(2015/02/19)
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- Concise copper-catalyzed synthesis of tricyclic biaryl ether-linked aza-heterocyclic ring systems
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A new method for the synthesis of tricyclic biaryl ether-linked ring systems incorporating seven-, eight-, and nine-membered ring amines is presented. In the presence of catalytic quantities of copper(I), readily accessible acyclic precursors undergo an intramolecular carbon-oxygen bond-forming reaction facilitated by a templating chelating nitrogen atom. The methodology displays a broad substrate scope, is practical, and generates rare and biologically interesting tricyclic heteroaromatic products that are difficult to access by other means.
- Mestichelli, Paola,Scott, Matthew J.,Galloway, Warren R. J. D.,Selwyn, Jamie,Parker, Jeremy S.,Spring, David R.
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p. 5448 - 5451
(2013/11/19)
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- Double palladium-catalyzed synthesis of azepines
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The synthesis of new 5H-pyridobenzazepine and 5H-dipyridoazepine compounds using as key step a palladium-catalyzed amination-cyclization reaction is reported. By choosing an appropriate combination of ligands and reactants under standardized reaction conditions, N- and S-tricyclic products can be prepared in one step from the appropriate stilbenes. Georg Thieme Verlag Stuttgart · New York.
- Bo?inovi?, Nina,Opsenica, Igor,?olaja, Bogdan A.
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supporting information
p. 49 - 52
(2013/02/23)
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- Transition-metal-free method for the synthesis of benzo[b]thiophenes from o -halovinylbenzenes and K2S via direct SNAr-type reaction, cyclization, and dehydrogenation process
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A new, highly efficient procedure for the synthesis of benzothiophenes from easily available o-halovinylbenzenes and potassium sulfide has been developed. The reaction tolerated a wide range of functionalities, and various 2-substituted benzo[b]thiophenes
- Zhang, Xiaoyun,Zeng, Weilan,Yang, Yuan,Huang, Hui,Liang, Yun
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supporting information
p. 1687 - 1692
(2013/09/02)
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- Z-selective copper-catalyzed asymmetric allylic alkylation with grignard reagents
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Allylic gem-dichlorides undergo regio- and enanantioselective (er up to 99:1) copper-catalyzed allylic alkylation with Grignard reagents affording chiral Z-vinyl chlorides. This highly versatile class of synthons can be subjected to Suzuki cross coupling affording optically active Z-alkenes and 1,3-cis,trans dienes.
- Giannerini, Massimo,Fananas-Mastral, Martin,Feringa, Ben L.
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supporting information; experimental part
p. 4108 - 4111
(2012/04/10)
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- Palladium-catalyzed double N-arylation to synthesize multisubstituted dibenzoazepine derivatives
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Palladium-catalyzed double N-arylation of primary amines with (Z)-1,2-bis(2-bromophenyl)ethenes was investigated. A variety of dibenzoazepine derivatives were synthesized in good to excellent yields.
- Zhang, Xiaoyun,Yang, Yuan,Liang, Yun
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supporting information
p. 6406 - 6408,3
(2012/12/12)
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- Unequivocal experimental evidence for a unified lithium salt-free wittig reaction mechanism for all phosphonium ylide types: Reactions with β-heteroatom-substituted aldehydes are consistently selective for cis-oxaphosphetane-derived products
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The true course of the lithium salt-free Wittig reaction has long been a contentious issue in organic chemistry. Herein we report an experimental effect that is common to the Wittig reactions of all of the three major phosphonium ylide classes (non-stabilized, semi-stabilized, and stabilized): there is consistently increased selectivity for cis-oxaphosphetane and its derived products (Z-alkene and erythro-β-hydroxyphosphonium salt) in reactions involving aldehydes bearing heteroatom substituents in the β-position. The effect operates with both benzaldehydes and aliphatic aldehydes and is shown not to operate in the absence of the heteroatom substituent on the aldehyde. The discovery of an effect that is common to reactions of all ylide types strongly argues for the operation of a common mechanism in all Li salt-free Wittig reactions. In addition, the results are shown to be most easily explained by the [2+2] cycloaddition mechanism proposed by Vedejs and co-workers as supplemented by Aggarwal, Harvey, and co-workers, thus providing strong confirmatory evidence in support of that mechanism. Notably, a cooperative effect of ortho-substituents in the case of semi-stabilized ylides is confirmed and is accommodated by the cycloaddition mechanism. The effect is also shown to operate in reactions of triphenylphosphine-derived ylides and has previously been observed for reactions under aqueous conditions, thus for the first time providing evidence that kinetic control is in operation in both of these cases.
- Byrne, Peter A.,Gilheany, Declan G.
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supporting information; experimental part
p. 9225 - 9239
(2012/07/14)
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- Synthesis of dibenz[a,h]anthracenes by Pd-catalyzed intramolecular double-cyclization of (Z,Z)-p-styrylstilbenes
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Dibenz[a,h]anthracene (1a) and its dimethoxy derivatives 1b and 1c were synthesized by the Pd-catalyzed intramolecular double-cyclization of the corresponding (Z,Z)-p-styrylstilbene derivatives 25, which were readily prepared by the Wittig reaction. The optical properties of the dibenz[a,h]anthracenes 1a1c are also presented.
- Umeda, Rui,Miyake, Satoshi,Nishiyama, Yutaka
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supporting information; experimental part
p. 215 - 217
(2012/05/20)
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- Palladium(0)-catalyzed arylative dearomatization of phenols
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The palladium-catalyzed arylative dearomatization of phenols to yield spirocyclohexadienone products in good to excellent yields has been developed. Preliminary results demonstrate that the formation of the spirocyclic all-carbon quaternary center can be accomplished with high levels of enantiocontrol (up to 91% ee).
- Rousseaux, Sophie,Garcia-Fortanet, Jorge,Del Aguila Sanchez, Miguel Angel,Buchwald, Stephen L.
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supporting information; experimental part
p. 9282 - 9285
(2011/08/04)
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- Synthesis of functionalizable boron-containing π-electron materials that incorporate formally aromatic fused borepin rings
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(Figure Presented) Not a natty B-OH: Borepin-based extended π-electron molecules contain bulky substituents that shield the vacant boron p orbitals and allow synthetic manipulation and purification under ambient conditions. These borepin-containing compounds (see picture; Mes* = 1,3,5-tris(tert-butyl) phenyl; B orange, C gray) display reversible cathodic electrochemistry and can be viewed as n-type analogues to bent acene hydrocarbons.
- Caruso Jr., Anthony,Siegler, Maxime A.,Tovar, John D.
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scheme or table
p. 4213 - 4217
(2010/08/07)
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- On the functionalization of [2.2](1,4)phenanthrenoparacyclophane
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Two routes for preparing functionalized [2.2](1,4) phenanthrenoparacyclophanes are described: either the parent system 2 is subjected to electrophilic substitution (bromination, Friedel-Crafts acylation, Rieche formylation: preparation of 5, 6, 7, 11 and 12) or the desired substituents are incorporated in the early stages of the synthesis by the preparation of the corresponding functionalized styryl paracyclophanes and their photocyclization to the respective phenanthrenocyclophanes. By these specific routes various bronudes (22a,b), ethers (28a-c) and phenols (29a,b) were synthesized. The latter derivatives, on oxidation, furnish para-(31) and ortho-quinonophanes (30, 32, 33), useful substrates for the preparation of cyclophanes containing phenazine subunits (36). The stilbene → phenanthrene photocyclization can also be employed for the preparation of benzothiophenophanes, e.g. 43 and 44, from the respective precursors. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
- Hopf, Henning,Hucker, Joachim,Ernst, Ludger
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p. 1891 - 1904
(2008/02/06)
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- Synthesis and chemistry of enantiomerically pure 10,11-dihydrodibenzo[b,f] thiepines
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Several chiral thiepines were efficiently constructed using sulfur diimidazole in combination with a variety of bislithiated carbon fragments. The sulfur atom in these thiepines is found to be unusually unreactive compared to diphenylsulfide. The Royal Society of Chemistry 2006.
- Wyatt, Paul,Hudson, Andrew,Charmant, Jonathan,Orpen, A. Guy,Phetmung, Hirihattaya
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p. 2218 - 2232
(2008/02/04)
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- The endocyclic restriction test: Oxygen transfer from N-sulfonyl oxaziridines to alkenes
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(formula presented) The transition state for the transfer of oxygen from N-sulfonyl oxaziridines to alkenes has been investigated experimentally using the endocyclic restriction test. Molecules containing oxaziridines and alkenes were prepared and the abi
- Anderson, David R.,Woods, Keith W.,Beak, Peter
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p. 1415 - 1417
(2008/02/09)
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- Phenacenes: A family of graphite ribbons. 2. Syntheses of some [7]phenacenes and an [11]phenacene by stilbene-like photocyclizations
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It is proposed that members of the family of polycyclic aromatic compounds with an extended phenanthrene-like structural motif be designated as [n]phenacenes, where n is the number of fused benzene rings. [n]Phenacene molecules are related to layers of gr
- Mallory, Frank B.,Butler, Kelly E.,Evans, Amanda C.,Brondyke, Emilie J.,Mallory, Clelia W.,Yang, Changqing,Ellenstein, Aviva
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p. 2119 - 2124
(2007/10/03)
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- Ortho-substituted benzofused macrocyclic lactams as zinc metalloprotease inhibitors
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The design and preparation of ortho-substituted benzofused macrocyclic lactams are described. The benzofused macrocyclic lactams were designed as neutral endopeptidase 24.11 (NEP) inhibitors. Docking studies were carried out in a model of thermolysin (TLN) using the MACROMODEL and QXP modeling programs to select suitable ring sizes. These studies predicted that the 11- , 12-, and 13-membered ring macrocyclic lactams would be active in both enzymes TLN and NEP. Good predictability of experimental results, within this series, of binding to thermolysin and to a lesser extent to NEP was observed. A visual comparison, docked at the active site of TLN, is presented for thiorphan, a 10-membered ring macrocycle and an 11-membered ring benzofused macrocyclic lactam. Potent inhibition of both NEP and thermolysin was obtained. The 11-membered ring macrocycle 25a is the most potent inhibitor from this series of compounds (TLN IC50 = 68 nM; NEP IC50 = 0.9 nM). The effects of prodrug 44b administered at 10 mg/kg po on plasma atrial natriuretic peptide (ANP) levels in conscious rats was greater than 200% over a 4 h period.
- Ksander, Gary M.,De Jesus, Reynalda,Yuan, Andrew,Ghai,Trapani,McMartin, Colin,Bohacek, Regine
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p. 495 - 505
(2007/10/03)
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- Phosphane ligands with two binding sites of differing hardness for enantioselective Grignard cross coupling
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A series of new, chiral phosphanes is presented, individual members of which were designed to serve as ligands in transition-metal mediated asymmetric Grignard cross coupling reactions. These ligands are characterized by a side chain containing one or two oxygen atoms with the capacity to act as binding sites for the incoming Grignard reagent. A number of structural parameters for the compounds was varied to learn about the reaction mechanism. Most of the ligands were tested in two cross coupling reactions, the formation of 3-phenylbut-1-ene and of 2,2′-dimethyl-1,1′-binaphthyl, respectively. Although both systems gave modest enantiomeric excesses it was not possible to make a comparison of their respective abilities.
- Terfort, Andreas,Brunner, Henri
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p. 1467 - 1479
(2007/10/03)
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- Phenacenes: A family of graphite ribbons. 1. Syntheses of some [7]phenacenes by stilbene-like photocyclizations
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The largest previously reported phenacene, the name we propose for the family of polycyclic aromatic compounds having fused benzene rings in an extended phenanthrene-like structural motif, contains only six rings ([6]phenacene). We have employed stilbene-like photocyclizations to synthesize the unsubstituted [7]phenacene, an extremely insoluble compound, as well as 2,13-di-n-pentyl[7]phenacene and 2,13-di-tert-butyl[7]phenacene, two alkyl-substituted derivatives with greatly improved solubilities.
- Mallory, Frank B.,Butler, Kelly E.,Evans, Amanda C.,Mallory, Clelia W.
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p. 7173 - 7176
(2007/10/03)
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- Heterodiene cycloadditoins of C2 symmetric 4,5-disubstituted ketene acetals: the nett asymmetric conjugate addition of recyclable acetic ester enolate equivalents to an activated enone
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Heterodiene cycloadditions of 3-formylchromone 2 to a series of ketene acetals 1 derived from C2 symmetric 1,2-diarylethane-1,2-diols are diastereoselective.From (S,S)-1,2-di(o-tolyl)ethane-1,2-diol 6c the major cycloadduct 3c was isolated by crystallization and transformed by acid-catalysed methanolysis into (S)-methyl 4-oxo-3,4-dihydro-2H-1-benzopyran-2-ylacetate 5, together with the original 1,2-diol 6c which could be recycled.The structures of two cyclic carbonates 22a and 22c were determined by X-ray diffraction and used as models in seeking a mechanistic rationale for the stereoselective cycloadditions of the analogous ketene acetals 1a and 1c.
- Wallace, Timothy W.,Wardell, Ian,Li, Ke-Dong,Leeming, Peter,Redhouse, Alan D.,Challand, S. Richard
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p. 2293 - 2308
(2007/10/02)
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- Interaction of tetrahydrostilbazoles with monoamine oxidase A and B
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1-Methyl-1,2,3,6-tetrahydrostilbazole (MTHS) and its analogs are oxidized by monoamine oxidase (MAO) A at slow rates comparable to that for the structurally similar neurotoxin, 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine, but the rates of oxidation by MAO B vary over a wide range depending on the structure of the analog. MAO A oxidation of all of the analogs yielded nonhyperbolic kinetic patterns, with little difference between the cis and trans isomers. In contrast MAO B showed hyperbolic kinetics and distinct stereoselectivity for the cis isomers. The corresponding pyridinium forms of trans-MTHS and its analogs were more potent inhibitors of MAO A (K(i) values between 0.3 and 5 μM) than of MAO B, for which the K(i) values varied greatly. The data suggest that the stringency of the MAO A active site for the geometry of the substrate molecule is less strict than that of MAO B. With MAO B, any substitution on the phenyl ring can lead to dramatic changes in the substrate properties which may be explained by the different orientation of substrate at the active site of the enzyme. Molecular geometry but not the effects of the substituents was shown to be an important factor in determining the effectiveness of substrate oxidation by MAO B.
- Sablin,Krueger,Singer,Bachurin,Khare,Efange,Tkachenko
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p. 151 - 157
(2007/10/02)
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- MAGNETIC COUPLING BETWEEN TWO PHENOXYL RADICALS ATTACHED TO THE PHENYL RINGS OF CIS- AND TRANS-STILBENES
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Magnetic coupling between two sterically protected phenoxyl radicals through the cis- and trans-stilbene chromophores was studied by means of their EPR fine structures.While the zero-field splitting parameters D, which are governed by the magnitude of dip
- Mitsumori, Teruyuki,Koga, Noboru,Iwamura, Hiizu
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- Vinyl Azides in Heterocyclic Synthesis. Part 10. Synthesis of the Isoindolobenzazepine Alkaloid Lennoxamine
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A total synthesis of the isoindolobenzazepine alkaloid lennoxamine (1), by a route involving vinyl azide chemistry, is described.Model studies on the azidocinnamates (12) and (13) revealed a striking difference between the (E)- and (Z)-isomers; whereas the (Z)-isomer (12) gave largely the 1-benzylisoquinoline (15) on decomposition, the (E)-isomer (13) gave the 2-aryl-3-benzazepine (14) as the major product.Consequently, in the lennoxamine synthesis, the azidocinnamate (26) bearing the (E)-alkenyl side chain, prepared from 6-bromopiperonal via the (E)-stilbene aldehyde (25) (Scheme 4), was decomposed to give the key 2-aryl-3-benzazepin e (27).Reduction of the double bonds in (27) was accompanied by cyclisation to the tetrahydroisoindolobenzazepine (30), which was converted into lennoxamine (1) by reduction of the ester group to an aldehyde, and decarbonylation.
- Moody, Christopher J.,Warrellow, Graham J.
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p. 2929 - 2936
(2007/10/02)
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- Photochemistry of chloro-2-vinylstilbenes
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Short irradiation at 300 nm of α-chloro- and β-chloro-2-vinylstilbene (20 and 21) leads to a mixture of 2-vinyltolane (35) and 2-vinylstilbene (1) accompanied by the cis- and trans-isomers of the starting compounds.Evidence is found for the occurrence of an ionic intermediate during the photolysis of 20 in methanol.At 360 nm, an additional, small amount of 1-chloro-endo- and 1-chloro-exo-6-phenylbenzobicyclohex-2-ene (39) is formed formed from 20.The elimination of hydrogen chloride also occurs during the irradiation of 2-(2-chlorovinyl)stilbene (23) and leads to 2-ethynylstilbene (41).The acetylenic compounds are photocyclized into 2-phenylnaphthalene (38).However, 2-(1-chlorovinyl)stilbene (22) reacts without loss of chlorine to give 1-chloro-exo-5-phenylbenzobicyclo-hex-2-ene (40).This exceptional reaction mode is due to a much higher rate of photocyclization resulting from less distortion in the stilbene moiety and a preference for a conformation better suited to the reaction of the 2-(1-chlorovinyl)stilbene molecule.It is shown that both isomers of 22 can photocyclize into 40.
- Brouw, P. M. op den,Laarhoven, W. H.
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