- Cyclopentanone ring expansion leading to functionalized δ-lactams: Short synthesis of simple sedum alkaloids
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Equation Presented Monosubstituted epoxides react with (cyclopentenyloxy) trimethylsilane to afford, after subsequent oxidative fragmentation, a pair of diastereomeric 8-membered iodolactones. When these lactones are separately treated with sodium azide,
- Maio, William A.,Sinishtaj, Sandra,Posner, Gary H.
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- AZEPANE DERIVATIVES AND METHODS OF TREATING HEPATITIS B INFECTIONS
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Provided herein are compounds useful for the treatment of HBV infection in a subject in need thereof, pharmaceutical compositions thereof, and methods of inhibiting, suppressing, or preventing HBV infection in the subject.
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Paragraph 0708; 0709; 0710
(2015/07/22)
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- AZEPANE DERIVATIVES AND METHODS OF TREATING HEPATITIS B INFECTIONS
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Provided herein are compounds useful for the treatment of HBV infection in a subject in need thereof, pharmaceutical compositions thereof, and methods of inhibiting, suppressing, or preventing HBV infection in the subject.
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Paragraph 0704
(2015/09/22)
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- Viability of 4,5-dihydro-1,2,3,4-oxatriazoles reinvestigated
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The first procedures to prepare 4-bromo-4-methylpentanal and 4-azido-4-methylpentanal are reported. The latter compound and also the parent 4-azidobutanal do not lead to 4,5-dihydro-1,2,3,4-oxatriazoles by intramolecular 1,3-dipolar cycloaddition, although it was claimed to be so in the literature. The NMR spectroscopic data of such heterocycles reported previously do not agree with those of similar substances and are incompatible with 13C NMR spectroscopic chemical shifts calculated by quantum chemical methods in the presented work. These calculations show furthermore that the intramolecular cycloaddition of 4-azidobutanals to give the title compounds is strongly endothermic and thus most probably not possible.
- Firdous, Samia,Banert, Klaus,Auer, Alexander A.
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experimental part
p. 5539 - 5543
(2011/06/21)
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- A concise approach towards the synthesis of WS75624 a and WS75624 B via the cross-metathesis of vinyl-functionalized thiazoles
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Synthetic approach towards precursors of WS75624 A and WS75624 B, two potent endothelin converting enzyme (ECE) inhibitors and potential antihypertensive agents, is reported featuring a key cross-metathesis between a vinyl-functionalized thiazole and a terminal olefin. As the two natural products only differ by the nature of their hydroxyalkyl side-chain, our convergent strategy enable the synthesis of key intermediates of both molecules in a limited amount of steps.
- Dash, Jyotirmayee,Melillo, Bruno,Arseniyadis, Stellios,Cossy, Janine
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experimental part
p. 2246 - 2249
(2011/05/05)
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- Pd(0)-catalyzed oxy- and aminoalkynylation of olefins for the synthesis of tetrahydrofurans and pyrrolidines
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The first Pd(0)-catalyzed intramolecular oxy- and aminoalkynylation of nonactivated olefins is reported. The reaction gives access to important tetrahydrofuran and pyrrolidine heterocycles with high diastereoselectivity. The unique synthetic potential of acetylenes is further exploited to access key building blocks for the synthesis of bioactive natural products.
- Nicolai, Stefano,Waser, Jerome
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supporting information; experimental part
p. 6324 - 6327
(2012/01/13)
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- Organocatalysis in a synthetic receptor with an inwardly directed carboxylic acid
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A cavitand functionalized with a Kemp-s triacid derivative was used to catalyze the epoxide ring-opening cyclizations of 1,5-epoxyalcohols. A deep, cylindrical cavity containing electron-rich aromatic walls and an inwardly directed carboxylic acid displayed the necessary characteristics to bind different 1,5-epoxyalcohols and initiate their cyclization reactions. The reactions inside this synthetic receptor occurred in a catalytic and regioselective manner. These results highlight that the arrangement of functionality and unique solvation provided by the structured interiors of natural enzymes can be incorporated into synthetic systems having useful physical and chemical properties. Copyright
- Shenoy, Siddhartha R.,Pinacho Crisostomo, Fernando R.,Iwasawa, Tetsuo,Rebek Jr., Julius
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p. 5658 - 5659
(2008/12/21)
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- NOVEL COMPOUNDS AS CANNABINOID RECEPTOR LIGANDS AND USES THEREOF
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The present invention relates to compounds of formula (I), or pharmaceutical salts, prodrugs, salts of prodrugs, or combinations thereof, wherein R1, R2, R3, and L1 are defined in the specfication, compositions comprising such compounds, and methods of treating conditions and disorders using such compounds and compositions. The present invention also relates to compounds of formula (II), or pharmaceutical salts, prodrugs, salts of prodrugs, or combinations thereof, wherein R1a, R2a and (Rx)n are as defined in the specification, compositions comprising such compounds, and methods of treating conditions and disorders using such compounds and compositions.
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Page/Page column 68
(2008/06/13)
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- Direct lactonization of alkenols via osmium tetroxide-mediated oxidative cleavage
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(Matrix presented) A highly efficient, mild, and simple protocol is presented for the tandem OsO4-mediated oxidative cleavage/oxidative lactonization of alkenols to lactones. The protocol couples the OsO 4-catalyzed oxidative cleavage of olefins with Oxone as the co-oxidant with the direct oxidation of aldehydes in alcoholic solvents to their corresponding esters.
- Schomaker, Jennifer M.,Travis, Benjamin R.,Borhan, Babak
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p. 3089 - 3092
(2007/10/03)
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- d0 Metal olefin complexes. Synthesis, structures, and dynamic properties of (C5R5)2Zr(OCMe2CH2CH2CH=CH2)+ complexes: Models for the elusive (C5R5)2Zr(R)(Olefin)+ intermediates in metallocene-based olefin polymerization catalysis
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To model the Zr-olefin interaction in the as-yet unobserved (C5R5)2Zr(R)(olefin)+ intermediates in (C5R5)2Zr(R)+-catalyzed olefin polymerization, the coordination of the tethered vinyl group in (C5R5)2Zr(OCMe2(CH2)(n)CH=CH2)+ species has been investigated. The reaction of (C5H5)2Zr(OCMe2CH2CH2CH= CH2)(Me) with B(C6F5)3 or [Ph3C][B(C6F5)4] yields the chelated olefin complex (C5H5)2Zr(OCMe2CH2CH2CH= CH2)+ as the MeB(C6F5)3- (12a) or B(C6F5)4- (12b) salts. In contrast, the reaction of (C5H5)2Zr(OCMe2CH2CH= CH2)(Me) with B(C6F5)3 in CD2Cl2 yields the MeB(C6F5)3- adduct (C5H5)2Zr(+)(OCMe2CH2CH=CH2)(μMe)B(-)(C6F5)3. The reaction of (C5H5)2Zr(OCMe2CH2CH2CH2CH=CH2)(Me) with B(C6F5)3 yields a 1.2/1 mixture (at -90 °C) of the chelated olefin complex (C5H5)2Zr(OCMe2CH2CH2CH2CH=CH2)+ and the MeB(C6F5)3- adduct (C5H5)2Zr(+)(OCMe2CH2CH2CH=CH2)(μ-Me)B(-)(C6F5)3'. The reaction of rac-(EBI)-Zr(OCMe2CH2CH2CH=CH2)(Me) (EBI = ethylene-1,2-bis(1-indenyl)) with B(C6F5)3 or [Ph3C] [B(C6F5)4] yields the chelated olefin complex rac-(EBI)Zr(OCMe2CH2CH2CH=CH2)+ as the MeB(C6F5)3- (20a) or B(C6F5)4-(20b) salts, each as a 1/1 mixture of diastereomers which differ in the relative configuration of the rac-(EBI)-Zr unit and the internal carbon of the coordinated olefin. X-ray diffraction analyses of 12a and the S,S,R/R,R,S isomer of 20a, and NMR data for 12a,b and 20a,b establish that the Zr-olefin bonding in these species is unsymmetrical and consists of a weak Zr-C(term) interaction and minimal Zr-C(int) interaction (12a, Zr-C(term) = 2.68(2), Zr-C(int) = 2.89(2) A; 20a, Zr-C(term) = 2.634(5), Zr-C(int) = 2.819(4) A). X-ray (d(C=C)), IR (v(C=C)), and NMR (1H, 13C) data show that the Zr-olefin interaction does not significantly perturb the structure of the coordinated olefin but does polarize the C=C bond such that positive charge buildup occurs at C(int). Similar unsymmetrical bonding and polarization effects may contribute to the high insertion reactivity of (C5R5)2Zr(R)(α-olefin)+ species. Dynamic NMR studies show that 12a,b and 20a,b undergo olefin face exchange in solution on the NMR time scale. The free energy barrier for face exchange of 20a (ΔG(+)(FE) = 15.4(4) kcal/mol at 43 °C) is significantly greater than that for 12a (ΔG(+)(FE) = 10.7(5) kcal/mol at -55 °C). Possible origins of this difference are discussed. The face exchange of 20a is dissociative, with minimal involvement of anion, solvent, or σ-complex intermediates.
- Carpentier, Jean-Francois,Wu, Zhe,Lee, Chul Woo,Stroemberg, Staffan,Christopher, Joseph N.,Jordan, Richard F.
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p. 7750 - 7767
(2007/10/03)
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- Intramolecular radical-chain hydrosilylation catalysed by thiols: Cyclisation of alkenyloxysilanes
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Alkenyloxy(diphenyl)silanes that contain a terminal double bond undergo radical-chain cyclisation at 60-65°C, in the presence of di-tert-butyl hyponitrite as initiator and a thiol as a catalyst. The thiol acts as a polarity-reversal catalyst and promotes the overall abstraction of hydrogen from the Si-H group in the alkenyloxysilane by the cyclic carbon-centred radical, formed by intramolecular addition of the corresponding silyl radical to the C=CH2 group. Allyloxysilanes give five-membered-ring products via 5-endo-trig cyclisation of the intermediate allyloxysilyl radical. Homoallyloxysilanes give mixtures of five- and six-membered heterocycles, but the intermediate silyl radicals undergo predominantly 6-endo cyclisation, in contrast to the corresponding carbon-centred radicals which cyclise preferentially in the 5-exo mode. An analogous pentenyloxysilane gives only the seven-membered-ring product via a 7-endo radical cyclisation. Steric effects play an important part in influencing the final-product stereochemistry when this is determined in the hydrogen-atom transfer reaction between the cyclic adduct radical and the thiol catalyst. Complementary EPR spectroscopic studies of the short-lived intermediate cyclic adduct radicals have been carried out in the absence of thiol and the structures and conformations of these species have been determined. It is emphasised that, for thiol catalysis of the overall cyclisation of alkenyloxysilanes to be successful, it is necessary for the addition of the chain-carrying thiyl radical to the C=CH2 group to be reversible under the reaction conditions.
- Cai, Yudong,Roberts, Brian P.
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p. 467 - 475
(2007/10/03)
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- Synthesis of medium-sized lactones by the copper(I)chloride/2,2′-bipyridine-catalyzed cyclization of di- and trichloroacetates
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Medium-sized lactones (eight- to eleven-membered rings) are efficiently formed by Cu(bpy)Cl catalyzed cyclization of various alkenyl di- and trichloroacetates at temperatures between 80 and 190°C in 1,2-dichloroethane or benzene as solvents. The mechanism of the alkene addition reaction is best understood as a chlorine atom transfer process through radical type intermediates. Exclusive endo-cyclization is observed in all cases. Ten and eleven-membered lactones are only accessible by the 'rigid chain' approach, in which an alkyne or alkene function is incorporated in the chain connecting the reaction centres, thus reducing the flexibility of the molecule.
- Pirrung, Frank O. H.,Hiemstra, Henk,Speckamp, W. Nico,Kaptein, Bernard,Schoemaker, Hans E.
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p. 12415 - 12442
(2007/10/02)
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- Oxymetallation. Part 24. Preparation of cyclic peroxides by cycloperoxymercuriation of unsaturated hydroperoxides
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Seventeen unsaturated hydroperoxides have been converted by treatment with mercury(II) acetate and/or mercury(II) nitrate into nineteen new mercuriated cyclic peroxides and by subsequent demercuriation with alkaline sodium borohydride, six new mercury-free peroxides have been isolated. The results greatly extend the range of such reactions and provide information about the stereoselectivities and relative ease of several different modes of cycloperoxymercuriation. It is suggested that the reactions with mercury(II) acetate are kinetically controlled whereas those with mercury(II) nitrate show a component of thermodynamic control of product distribution.
- Bloodworth,Curtis,Spencer,Tallant
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p. 2729 - 2750
(2007/10/02)
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- Sandalwood odorants
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The present invention relates to novel substituted cyclohexanol compounds possessing a sandalwood aroma which are useful as fragrance materials. The invention also provides methods for synthesis thereof through a novel aldehyde intermediate. The compounds of the invention have the formula: STR1 wherein A is STR2 and wherein R1 is methyl or ethyl, R2 -R7 are independently hydrogen or methyl with the proviso that a maximum of two of the substituents R2 -R7 are methyl, and R8 is hydrogen, lower alkyl (C1 to C5) or acyl. The invention also provides fragrance compositions which utilize the compounds of the invention to impart a sandalwood aroma to perfume compositions, colognes and perfumed articles.
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- An Electron Spin Resonance Study of the Regioselectivity of the Cyclization of Protonated and Unprotonated Pent-4-en-1-oxyl and Pent-4-en-1-peroxyl Radicals
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The regioselectivity of the ring closure of protonated and unprotonated pent-4-en-1-oxyl radicals has been determined by monitoring by e.s.r. spectroscopy the radicals which are formed when the corresponding pent-4-enyl peroxides (2; R = H or Me) are photolysed in solution.Under neutral conditions, the spectra of the corresponding tetrahydrofuran-2-ylmethyl radicals (6) are observed, confirming the preferential 5-exo-mode of cyclization.When trifluoroacetic acid is present, the different spectra of the protonated tetrahydrofuran-2-ylmethyl radicals (8) are observed, and it is argued that this reflects the similar regioselectivity of the intramolecular addition of the protonated alkoxyl radicals.The identity of the radicals (6) and (8) was confirmed by generating them independently by abstracting bromine atoms from the corresponding bromides (9).Similar experiments with the hydroperoxides (1) failed to show the spectra of the dioxan-3-ylmethyl radicals (17), perhaps because they rapidly undergo γ-scission to the oxygen-centred radicals (18).However, (17) could be trapped with oxygen to afford, after Ph3P reduction, 1,2-dioxanes (4).No evidence could be found for the protonation of alkylperoxyl radicals by trifluoroacetic acid.
- Bloodworth, A. J.,Davies, Alwyn G.,Hay-Motherwell, Robyn S.
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p. 575 - 582
(2007/10/02)
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- A HIGHLY EFFICIENT SYNTHESIS OF γ- AND δ-LACTONES BY OXIDATIVE CYCLIZATION
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Treatment of tertiary γ- and δ-hydroxyolefins with pentavalent chromium reagent, (BipyH2)CrOCl5, give good yields of γ- and δ-lactones by oxidative cyclization, with loss of one carbon.Pyridinium chlorochromate (PCC) also effect this transformation to γ-lactones in reasonable yields.
- Chakraborty, T. K.,Chandrasekaran, S.
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p. 551 - 554
(2007/10/02)
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- Occurrence of Electron Transfer in the Reduction of Organic Halides by LiAlH4 and AlH3
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A variety of methods have been utilized to detect the occurrence of a single electron transfer pathway in the reduction of alkyl halides by LiAlH4 and AlH3, i.e., (1) product studies of reduction of cyclizable alkyl halides containing the 5-hexenyl group, (2) trapping of intermediate radicals by dicyclohexylphosphine and other trapping agents, (3) direct EPR observation of the trityl radical in the reduction of trityl bromide, and (4) stereochemical studies of the reduction of secondary halides by lithium aluminum deuteride.The extent of electron transfer was found to be a function of the solvent, the substrate, the leaving group, and the hydride reagent.For alkyl iodides, and to a lesser extent bromides, electron transfer was found to be the major reaction pathway; however, no evidence for electron transfer was found for the corresponding chlorides or tosylates.Reduction of (+)-2-octyl iodide by LiAlD4 was found to be much less stereospecific than the corresponding reduction of bromide, chloride, or tosylate, indicating intermediate radical formation in the reduction of the secondary iodide.
- Ashby, E. C.,DePriest, R. N.,Goel, A. B.,Wenderoth, Bernd,Pham, Tung N.
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p. 3545 - 3556
(2007/10/02)
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