- INTRAMOLECULAR CYCLOADDITION AND SEQUENTIAL RING EXPANSION
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Free radical expansion of fused-cyclobutanones gives bicyclic ketones expanded by three and four carbons, with the carbonyl group β to the ring junction.Four-carbon ring expansion shows stereoselectivity favoring the trans-fused product 6-trans.The radical precursor cyclobutanones are readily prepared by intramolecular cycloaddition of ketenes or keteniminium salts to olefins.
- Zhang, Wei,Collins, Michael R.,Mahmood, Khalid,Dowd, Paul
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- A short synthesis of (±)-alloyohimbane via a thioisomunchnone based intramolecular dipolar-cycloaddition reaction
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Thioisomunchnone dipoles were generated by the reaction of bromoalkenoyl chlorides with thioamides. The intramolecular dipolar-cycloaddition reaction was used for a short synthesis of the yohimbanoid alkaloid (±)- alloyohimbane.
- Heidelbaugh, Todd M.,Liu, Bing,Padwa, Albert
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- Hypervalent λ(n)-iodane-mediated fragmentation of tertiary cyclopropanol systems
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The oxidation of tertiary cyclopropyl silyl ethers with hypervalent λ(n)-iodanes caused fragmentation which produced alkenoic acids or esters.
- Kirihara, Masayuki,Yokoyama, Satoshi,Kakuda, Hiroko,Momose, Takefumi
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- Enzymatic Oxidative Tandem Decarboxylation of Dioic Acids to Terminal Dienes
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The biocatalytic oxidative tandem decarboxylation of C7–C18dicarboxylic acids to terminal C5–C16dienes was catalyzed by the P450 monooxygenase OleT with conversions up to 29 % for 1,11-dodecadiene (0.49 g L–1). The sequential nature of the cascade was proven by the fact that decarboxylation of intermediate C6–C11ω-alkenoic acids and heptanedioic acid exclusively gave nonconjugated 1,4-pentadiene; scale-up allowed the isolation of 1,15-hexadecadiene and 1,11-dodecadiene; the system represents a short and green route to terminal dienes from renewable dicarboxylic acids.
- Dennig, Alexander,Kurakin, Sara,Kuhn, Miriam,Dordic, Andela,Hall, Mélanie,Faber, Kurt
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- Experimental determination of the activation parameters and stereoselectivities of the intramolecular Diels-Alder reactions of 1,3,8-nonatriene, 1,3,9-decatriene, and 1,3,10-undecatriene and transition state modeling with the Monte Carlo-Jumping between Wells/molecular dynamics method
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Experimental activation parameters for the intramolecular Diels-Alder reactions of 1,3,8-nonatriene, 1,3,9-decatriene, and 1,3,10-undecatriene have been measured, and the Monte Carlo-Jumping between Wells/Stochastic Dynamics [MC(JBW)/SD] method, which gives relative free energies of activation, was tested as a means to predict stereoselectivities. The predictions are compared to experimental results, and to predictions from quantum and molecular mechanics methods.
- Diedrich, Matthias K.,Kl?rner, Frank-Gerrit,Beno, Brett R.,Houk,Senderowitz, Hanoch,Still, W. Clark
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- A Highly Catalytic and Selective Conversion of Carboxylic Acids to 1-Alkenes of One Less Carbon Atom
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An equimolar mixture of a carboxylic acid and acetic anhydride produces a reagent combination that undergoes a highly efficient decarbonylation/dehydration at 250 deg C using either Pd- or Rh-based catalyst systems, affording excellent yields of the corresponding 1-alkenes of one less carbon atom.
- Miller, Joseph A.,Nelson, Jeffrey A.,Byrne, Michael P.
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- New alkaloidal metabolites from cultures of entomopathogenic fungus Cordyceps takaomontana NBRC 101754
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Two new alkaloidal metabolites, cordytakaoamides A (1) and B (2), as well as, 2-[(2-hydroxyethyl) amino] benzoic acid (3) and 2E-decenamide (4), and three known compounds (5–7) were isolated from ethyl acetate and n-butanol soluble portions of the entomopathogenic fungus, Cordyceps takaomontana NBRC 101754. Compounds 3 and 4 were isolated here for first time from natural resources. The chemical structures were established depending upon spectroscopic techniques such as 1D, 2D NMR, and HRMS. The absolute configuration of 1 and 2 was elucidated via the total synthesis of 1 as well as the experimental circular dichroism. Compound 3 was confirmed by a signal crystal X-ray analysis.
- Hama, Maichi,Elshamy, Abdelsamed I.,Yoneyama, Tatsuro,Kasai, Yusuke,Yamamoto, Hirohumi,Tanigawa, Kana,Oshiro, Ayari,Noji, Masaaki,Ban, Sayaka,Imagawa, Hiroshi,Umeyama, Akemi
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- Synthesis of unsaturated dibasic acid esters from five-, six-, and seven-membered cycloalkanones
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A new route to diesters of symmetrical octene-, decene-, and dodecenedioic acids was proposed. The ratio of the cis/trans-isomers was 1:4. The synthesis involved oxidative splitting of five-, six-, and seven-membered cycloalkanones with hydrogen peroxide into the corresponding ω-alkenoic acids followed by esterification and metathesis over Re2O7/B 2O3-Al2O3-SnMe4.
- Starostin,Furman,Ignatenko,Barkova,Nikishin
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- Ni-Catalyzed β-Alkylation of Cyclopropanol-Derived Homoenolates
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Metal homoenolates are valuable synthetic intermediates which provide access to β-functionalized ketones. In this report, we disclose a Ni-catalyzed β-alkylation reaction of cyclopropanol-derived homoenolates using redox-active N-hydroxyphthalimide (NHPI) esters as the alkylating reagents. The reaction is compatible with 1°, 2°, and 3° NHPI esters. Mechanistic studies imply radical activation of the NHPI ester and 2e β-carbon elimination occurring on the cyclopropanol.
- Mills, L. Reginald,Zhou, Cuihan,Fung, Emily,Rousseaux, Sophie A. L.
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supporting information
p. 8805 - 8809
(2019/11/03)
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- Ni-Catalyzed Carboxylation of Unactivated Alkyl Chlorides with CO2
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A catalytic carboxylation of unactivated primary, secondary, and tertiary alkyl chlorides with CO2 at atmospheric pressure is described. This protocol represents the first intermolecular cross-electrophile coupling of unactivated alkyl chlorides, thus leading to new knowledge in the cross-coupling arena.
- B?rjesson, Marino,Moragas, Toni,Martin, Ruben
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supporting information
p. 7504 - 7507
(2016/07/06)
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- Low catalyst loading in ring-closing metathesis reactions
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An efficient procedure is described for ring-closing metathesis reactions. A conversion of 95 % for diethyl diallylmalonate in dilute solution could be achieved within a few minutes, reaching TOF=4173min-1, with very low loading of commercially available Ru catalysts that contained unsaturated NHC ligands. In general, only 50 to 250ppm of the catalyst is required to achieve near-quantitative conversion into a broad variety of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-tert-butoxycarbonyl (N-Boc)- and N-para-toluenesulfonyl (N-Ts)-protected cyclic amines and 9-16-membered lactones. The synthesis of macrocyclic proline-based lactams required slightly higher catalyst loadings. Along with monocyclic products, oligomeric byproducts, mostly cyclodimers, were isolated and characterized. Getting some closure: An efficient procedure is described for ring-closing metathesis reactions in which only 50 to 250ppm of catalyst is required to effect almost-quantitative conversion into a broad range of 5-16-membered heterocyclic compounds. The practicality of this procedure was illustrated in the synthesis of 5-8-membered N-protected cyclic amines, 9-16-membered lactones, and 11-16-membered proline-based lactams. Copyright
- Kadyrov, Renat
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p. 1002 - 1012
(2013/02/23)
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- MACROCYCLIC COMPOUNDS AND RELATED COMPOSITONS AND METHODS OF USE
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Compounds and compositions, which can be use for example, for treating cancer, are described herein.
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Page/Page column 58
(2013/03/26)
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- Reductive carboxylation of alkyl halides with CO2by use of photoinduced SmI2/Sm reduction system
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Upon visible-light irradiation, reductive carboxylation of alkyl halides takes place by using a Sml2/Sm mixed system under atmospheric CO 2 to afford the corresponding carboxylic acids in good to excellent yields.
- Nomoto, Akihiro,Kojo, Yusuke,Shiino, Go,Tomisaka, Yuri,Mitani, Ikuko,Tatsumi, Masahiko,Ogawa, Akiya
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scheme or table
p. 6580 - 6583
(2011/02/24)
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- Combination of RCM and the Pauson-Khand reaction: One-step synthesis of tricyclic structures
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The combination of ring-closing metathesis (RCM) followed by an intramolecular Pauson-Khand reaction gives direct entry to tricyclic compounds. The RCM was carried out on a hexacarbonylcobalt-complexed alkyne, this complex acting as a protecting group against enyne metathesis. The procedure was studied for dienynes containing heteroatoms and allows the building of [6,5,5] and [7,5,5] tricyclic systems. The feasibility of the process depends strongly on the nature of the substrate. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Rosillo, Marta,Arnaiz, Eduardo,Abdi, Delbrin,Blanco-Urgoiti, Jaime,Dominguez, Gema,Perez-Castells, Javier
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experimental part
p. 3917 - 3927
(2009/04/07)
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- A one-pot bicycloannulation method for the synthesis of tetrahydroisoquinoline systems
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A highly effective method for the synthesis of the core indolo[2,3- α]quinolizidine skeleton found in yohimbine is described. The reaction of N- monosubstituted thioamides with bromoalkenoyl chlorides furnishes thioisomunchnones as transient 1,3-dipoles that undergo ready intramolecular cycloaddition across the tethered π-bond to give thio-bicycloannulated products in a one-pot operation. The stereochemical outcome of the intramolecular reaction is the consequence of an endo cycloaddition of the neighboring π-bond across the transient thioisomunchnone dipole. A major limitation of the method is that when a hydrogen is present in the α- position of the thioamide the initially formed thio-N-acyliminium ion undergoes proton loss to produce a S,N-ketene acetal at a faster rate than dipole formation. Treatment of tetrahydro-β-carboline-1-thione with 2- bromooct-7-enoyl chloride followed by reductive removal of sulfur from the cycloadduct resulted in the formation of (±)-alloyohimbanone. Attempts to cycloadd the thioisomunchnone dipole across several nucleophilic π-bonds failed, and instead, products derived from cyclization of the π-bond onto the initially formed thio-N-acyliminium ion were formed. The resulting N,S- ketals were further converted into several tetrahydroisoquinoline alkaloids in good yield.
- Padwa, Albert,Beall, L. Scott,Heidelbaugh, Todd M.,Liu, Bing,Sheehan, Scott M.
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p. 2684 - 2695
(2007/10/03)
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- Quinoline analogs of mevalonolactone and derivatives thereof
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Quinoline analogs of mevalonolactone of the following formula are useful as anti-cholesterol synthesis agents: STR1 where the substituents are as defined in the specification.
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- Thermodynamic and nuclear magnetic resonance study of the reactions of α- and β-cyclodextrin with acids, aliphatic amines, and cyclic alcohols
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Titration calorimetry was used to determine equilibrium constants and standard molar enthalpy, Gibbs energy, and entropy changes for the reactions of a series of acids, amines, and cyclic alcohols with α- and β-cyclodextrin. The results have been examined in terms of structural features in the ligands such as the number of alkyl groups, the charge number, the presence of a double bond, branching, and the presence of methyl and methoxy groups. The values of thermodynamic quantities, in particular the standard molar Gibbs energy, correlate well with the structural features in the ligands. These structural correlations can be used for the estimation of thermodynamic quantities for related reactions. Enthalpy-entropy compensation is evident when the individual classes of substances studied herein are considered, but does not hold when these various classes of ligands are considered collectively. The NMR results indicate that the mode of accommodation of the acids and amines in the α-cyclodextrin cavity is very similar, but that the 1-methyl groups in 1-methylhexylamine and in 1-methylheptylamine and the N-methyl group in N-methylhexylamine lie outside the α-cyclodextrin cavity. This latter finding is consistent with the calorimetric results. Many of the thermodynamic and NMR results can be qualitatively understood in terms of van der Waals forces and hydrophobic effects.
- Rekharsky, Mikhail V.,Mayhew, Martin P.,Goldberg, Robert N.,Ross, Philip D.,Yamashoji, Yuko,Inoue, Yoshihisa
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- Unusual products from dirhodium tetraacetylate-catalyzed decomposition of diazoacetylcycloalkanes
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Rh2(OAc)4-assisted decompositions of diazoacetylcycloalkanes are shown to yield cycloalkylacetic acids (Wolff rearrangement), unexpected cycloalkylcarboxylic acids and bicyclic ketones (intramolecular C-H bond insertion). Rh2(OCOF3)4-promoted reactions, on the other hand, have furnished bicyclic ketones and ketene dimers.
- Ceccherelli, Paolo,Curini, Massimo,Marcotullio, Maria Carla,Pisani, Emanuela,Rosati, Ornelio,Wenkert, Ernest
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p. 8501 - 8506
(2007/10/03)
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- Molecular oxygen oxidative carbon-carbon bond cleavage of α-ketols catalysed by Bi(III) carboxylates
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Bi(III)-mandelate catalyses the oxidative carbon-carbon bond cleavage, by molecular oxygen, of a series of α-ketols into the corresponding carboxylic acids. The reaction is accelerated in the presence of DMSO.
- Le Boisselier, Veronique,Coin, Christine,Postel, Michele,Dunach, Elisabet
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p. 4991 - 4996
(2007/10/02)
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- Process for the preparation of a R-alpha cyclopentenones and R-alpha and R-omega cyclopentanoids
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A process for the preparation of Rα-cyclopentenoids and then Rα, Rω-cyclopentanoids is described. The process involves the reaction of a compound of the formula STR1 where X is halo, particularly Br or I and P is a protecting group with an alkylborane to produce the Rα-cyclopentenone. The Rα-cyclopentenone is reacted with a Rω cuprate to produce the Rα, Rω-cyclopentenoid. The process is used for the preparation of prostaglandins which are known pharmaceutically active compounds.
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- Studies on the Intramolecular Cycloaddition Reaction of Mesoionics Derived from the Rhodium(II)-Catalyzed Cyclization of Diazoimides
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A series of alkenyl-substituted imides were prepared by treating the appropriate amide with 2,2,6-trimethyl-4H-1,3-dioxen-4-one in xylene at 140 deg C to give the N-acetoacylated imides.Exposure of these imides to standard diazo transfer conditions gave the desired diazoimides.The carbenoid intermediate derived by treatment of the diazoimide with rhodium(II) acetate undergoes ready cyclization onto the neighboring amide carbonyl oxygen atom to generate an isomuenchnone intermediate.Subsequent 1,3-dipolar cycloaddition across the pendant olefin affords the cycloadduct in high yield.The stereochemical assignment of several of the cycloadducts was deduced by X-ray crystallography.The stereochemical outcome of the reaction is the consequence of an endo cycloaddition of the neighboring ?-bond across the transient isomuenchnone dipole.Molecular mechanics calculations were used to model energy differences between the endo and exo diastereomers.The calculations reveal that the endo diastereomers are significantly (8-12 kcal/mol) lower in energy than the corresponding exo isomers thereby providing a rationale for the preferred endo cycloaddition.Ring opening of the cycloadducts occured readily producing a transient N-acyliminium ion which either lost a proton to give an enamide or was reduced by Et3SiH to afford a bicyclic piperidine ring.
- Padwa, Albert,Hertzog, Donald L.,Nadler, William R.,Osterhout, Martin H.,Price, Alan T.
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p. 1418 - 1427
(2007/10/02)
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- Bi(III)-mandelate/DMSO : A New Oxidizing System for the Catalyzed C-C Cleavage of Epoxides
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Bi(III)-mandelate was found to be an effective catalyst for the oxidative C-C bond cleavage of epoxides and their transformation into carboxylic acids in anhydrous DMSO medium.
- Zevaco, Thomas,Dunach, Elisabet,Postel, Michele
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p. 2601 - 2604
(2007/10/02)
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- Process for making olefins
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Carboxylic acids are converted in high yields to olefins or high purity α-olefins by contacting a mixture of carboxylic acid and a carboxylic acid anhydride in the presence of a Group VIII metal or copper-containing catalyst at a temperature of from about 100° C. to about 300° C.
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- OXIDATIVE DEBENZYLATION OF 4-METHOXY-α-METHYLBENZYL ESTERS
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4-Methoxy-α-methylbenzyl alcohol was introduced as a new protecting group for carboxylic acids. 4-Methoxy-α-methyl benzyl esters obtained from the coupling of 4-methoxy-α-methylbenzyl alcohol and corresponding acids, were hydrolyzed in good yield by 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ).This process is compatible with several functional groups which are vulnerable to the reductive debenzylation reaction.
- Yoo, Sung-Eun,Kim, Hye Ryung,Yi, Kyu Yang
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p. 5913 - 5916
(2007/10/02)
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- STANNYL ESTER CYCLIZATIONS
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Alpha halo stannyl esters react with alkenes to afford lactones.The reaction is catalyzed by AIBN.The reaction proceeds best with electron rich alkenes.The mechanistic aspects of this novel reaction are discussed.This reaction can also be conducted intramolecularly to produce bicyclic lactones.An approach to the lignan system is presented.
- Kraus, George A.,Landgrebe, Kevin
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p. 4039 - 4046
(2007/10/02)
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- Urazole analogs of prostaglandins
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Compounds of formula (I) STR1 wherein: n is 1 to 5 Y is --CH2 --CH2 or --CH=CH--; R1 is hydrogen or CO2 R1 represents an ester group in which the R1 moiety contains from 1-12 carbon atoms; R2 is hydrogen, C1-4 alkyl, or phenyl; R3 is hydroxy or protected hydroxy; R4 is hydrogen, C1-9 alkyl, C3-8 cycloalkyl, C3-8 cycloalkyl-C1-6 alkyl, phenyl, phenyl --C1-6 alkyl, naphthyl, naphthyl C1-6 alkyl, any of which phenyl moieties or naphthyl moieties may be substituted by one or more halogen, trifluoromethyl, C1-6 alkyl, hydroxy, C1-6 alkoxy, phenyl C1-6 alkoxy or nitro groups; R5 is hydrogen, C1-6 alkyl, C5-8 cycloalkyl, phenyl, phenyl-C1-6 alkyl or phenyl C3-6 cycloalkyl, any of which phenyl moieties may be substituted by one or more halogen, trifluoromethyl, C1-6 alkyl, C1-6 alkoxy or nitro groups; or R2 and R4 taken with the carbon atom to which they are joined represent a C5-8 cycloalkyl group; and salts thereof are useful for their prostaglandin-like activity.
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