- Application of a metathesis reaction in the synthesis of sterically congested medium-sized rings. A direct ring closing versus a double bond migration-ring closing process
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An efficient double bond migration-ring closing metathesis reaction leading to cycloheptene derivatives is observed when specific sterically congested 1,9-dienes are treated with the Grubbs' imidazolidene ruthenium catalyst. The simultaneous use of the Grubbs' catalyst and RuClH(CO)(PPh3) 3 facilitates the tandem bond migration-metathesis process. RuClH(CO)(PPh3)3 alone is capable of triggering an unactivated double bond migration that may have preparative applications.
- Michalak, Michal,Wicha, Jerzy
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Read Online
- Total synthesis of (+)-petromyroxol via tandem α-aminoxylation-allylation and asymmetric dihydroxylation-SN2 cyclization approach
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The total synthesis of (+)-petromyroxol, a tetrahydrofuran (THF)-diol fatty acid, isolated from sea lamprey larvae (Petromyzon marinus) is reported. The present synthesis employs a tandem α-aminoxylationallylation, cross metathesis and tandem asymmetric d
- Nookaraju,Kumar, Pradeep
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Read Online
- On the Mechanism of the Ethyl Elimination from the Molecular Ion of 6-Methoxy-1-Hexene
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It is shown by 13C and D labelling that the ethyl radical elimination from the molecular ion of 6-methoxy-1-hexene is a very complex process involving at least two different channels.The major channel (80percent) is induced by an initial 1,5-hydrogen shift in the molecular ion from C(5) to C(1) leading via a series of steps to methoxycyclohexane, which then undergoes a ring contraction to 2-methyl-1-methoxycyclopentane, being the key intermediate for the ethyl loss.The same key intermediate is formed in the other, minor channel (20percent) by ring closure directly following an initial 1,6-hydrogen shift in the molecular ion of 6-methoxy-1-hexene from C(6) to C(1).Collision-induced dissociation experiments on the + ion from 6-methoxy-1-hexene have further established that it has the unique structure of oxygen methyl cationized 2-methylpropen-2-al.This ion is also generated by ethyl loss from the molecular ion of 2-methyl-1-methoxycyclopentane itself, as shown by collision-induced dissociation experiments, thus confirming the key role of the intermediate mentioned.
- Molenaar-Langeveld, Tineke A.,Fokkens, Roel H.,Nibbering, Nico M. M.
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Read Online
- Electrochemical Proton Reduction over Nickel Foam for Z-Stereoselective Semihydrogenation/deuteration of Functionalized Alkynes
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Selective reduction strategies based on abundant-metal catalysts are very important in the production of chemicals. In this paper, a method for the electrochemical semihydrogenation and semideuteration of alkynes to form Z-alkenes was developed, using a simple nickel foam as catalyst and H3O+ or D3O+ as sources of hydrogen or deuterium. Good yields and excellent stereoselectivities (Z/E up to 20 : 1) were obtained under very mild reaction conditions. The reaction proceeded with terminal and nonterminal alkynes, and also with alkynes containing easily reducible functional groups, such as carbonyl groups, as well as aryl chlorides, bromides, and even iodides. The nickel-foam electrocatalyst could be recycled up to 14 times without any change in its catalytic properties.
- Valiente, Alejandro,Martínez-Pardo, Pablo,Kaur, Gurpreet,Johansson, Magnus J.,Martín-Matute, Belén
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- Accelerated Semihydrogenation of Alkynes over a Copper/Palladium/Titanium (IV) Oxide Photocatalyst Free from Poison and H2 Gas
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Selective hydrogenation of alkynes to alkenes (semihydrogenation) without the use of a poison and H2 is challenging because alkenes are easily hydrogenated to alkanes. In this study, a titanium (IV) oxide photocatalyst having Pd core-Cu shell nanoparticles (Pd@Cu/TiO2) was prepared by using the two-step photodeposition method, and Pd@Cu/TiO2 samples having various Cu contents were characterized by electron transmission microscopy, X-ray photoelectron spectroscopy and UV-vis spectroscopy. Thus-prepared Pd@Cu/TiO2 samples were used for photocatalytic hydrogenation of 4-octyne in alcohol and the catalytic properties were compared with those of Pd/TiO2 and Cu/TiO2. 4-Octyne was fully hydrogenated to octane over Pd/TiO2 at a high rate and 4-octyne was semihydrogenated to cis-4-octene over Cu/TiO2 at a low rate. Rapid semihydrogenation of 4-octyne was achieved over Pd(0.2 mol%)@Cu(1.0 mol%)/TiO2, indicating that the Pd core greatly activated the Cu shell that acted as reaction sites. A slight increase in the reaction temperature greatly increased the rate with a suppressed rate of H2 evolution as the side reaction. Changes in the reaction rates of the main and side reactions are discussed on the basis of results of kinetic studies. Reusability and expandability of Pd@Cu/TiO2 in semihydrogenation are also discussed.
- Imai, Shota,Nakanishi, Kousuke,Tanaka, Atsuhiro,Kominami, Hiroshi
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p. 1609 - 1616
(2020/02/15)
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- Synthesis of a C1-C12 Fragment of Gulmirecin B
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The synthesis of a C1-C14 fragment of the macrolide antibiotic gulmirecin B through formation of the C7-C8 bond by addition of a vinyllithium intermediate to a C1-C7 aldehyde was investigated. This crucial coupling was successful with a vinyllithium reagent corresponding to a C8-C12 fragment. The C8-C12 vinyl bromide was prepared from l -malic acid. The C1-C7 aldehyde building block was synthesized from hex-5-enoic acid by using an Evans alkylation, a cross-metathesis, and an asymmetric dihydroxylation as key steps.
- Maier, Martin E.,Rengarasu, Rathikrishnan
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supporting information
p. 1346 - 1350
(2019/06/20)
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- Highly active bidentate N-heterocyclic carbene/ruthenium complexes performing dehydrogenative coupling of alcohols and hydroxides in open air
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Eight bidentate NHC/Ru complexes, namely [Ru]-1-[Ru]-8, were designed and prepared. In particular, [Ru]-2 displayed extraordinary performance even in open air for the dehydrogenative coupling of alcohols and hydroxides. Notably, an unprecedentedly low catalyst loading of 250 ppm and the highest TON of 32 800 and TOF of 3200 until now were obtained.
- Wang, Zhi-Qin,Tang, Xiao-Sheng,Yang, Zhao-Qi,Yu, Bao-Yi,Wang, Hua-Jing,Sang, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
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supporting information
p. 8591 - 8594
(2019/07/25)
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- Method for preparing 5-hexenic acid
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The invention discloses a method for preparing 5-hexenic acid. A catalyst adopted by the method comprises iron hexafluorophosphate, a rare-earth-containing titanium-silicon molecular sieve and perfluorosulfonic acid and is used for catalyzing cyclohexanone and peroxide to be subjected to oxidization reaction to prepare the 5-hexenic acid; the method has the characteristics that the selectivity ishigh, a product is easy to separate, post-treatment is simple and the like; the utilized catalyst also can be recycled and repeatedly utilized.
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Paragraph 0038; 0044; 0045; 0052
(2018/12/13)
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- Additive-modulated switchable reaction pathway in the addition of alkynes with organosilanes catalyzed by supported Pd nanoparticles: Hydrosilylation: versus semihydrogenation
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We herein report supported Pd nanoparticles on N,O-doped hierarchical porous carbon as a single operation catalyst-enabled additive-modulated reaction pathway for alkynes addition with organosilanes between hydrosilyation and semihydrogenation. In the case of alkynes hydrosilylation, a simple iodide ion as an additive has a promotion effect on the activity and regio- and stereoselectivity, where iodide can coordinate with Pd NPs via strong δ donation to increase the electron density of the Pd atom, resulting in an increased ability for the oxidative addition of hydrosilane as the rate-determining step to make the reaction proceed efficiently to afford vinylsilanes in high yields with excellent regio- and stereoselectivity. For the catalytic transfer semihydrogenation of alkynes, water was introduced to mix with organosilane to form a silanol together with the generation of hydrogen atoms on the Pd NPs surface or the liberation of H2 gas as a reducing agent, whereby the quantitative reduction of alkynes was achieved with exclusive selectivity to alkenes. In both cases, the catalyst could be recycled several times without a significant loss in activity or selectivity. A broad range of alkyl and aryl alkynes with various functional groups are compatible with the reaction conditions. The role the additive exerted in each reaction was extensively investigated through control experiments as well as the kinetic isotopic effect along with spectroscopic characterization. In addition, the respective mechanism operating in both reactions was proposed.
- Duan, Yanan,Ji, Guijie,Zhang, Shaochun,Chen, Xiufang,Yang, Yong
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p. 1039 - 1050
(2018/03/05)
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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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supporting information
p. 3473 - 3477
(2016/07/29)
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- Fluorine in fragrances: Exploring the difluoromethylene (CF2) group as a conformational constraint in macrocyclic musk lactones
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The CF2 group is incorporated into specific positions within the lactone ring of the natural musk lactone, (12R)-(+)-12-methyl-13-tridecanolide, a constituent of Angelica root oil, Angelica archangelica L. The approach is taken as it was antici
- Corr, Michael J.,Cormanich, Rodrigo A.,Von Hahmann, Cortney N.,Bühl, Michael,Cordes, David B.,Slawin, Alexandra M. Z.,O'Hagan, David
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supporting information
p. 211 - 219
(2015/12/30)
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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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- Baeyer-villiger oxidation and oxidative cascade reactions with aqueous hydrogen peroxide catalyzed by lipophilic Li[B(C6F5) 4] and Ca[B(C6F5)4]2
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Efficient and selective: Two lipophilic catalysts were used for Baeyer-Villiger (BV) oxidations to give lactones in high yields (see scheme). Cascade reactions involving this BV oxidation were used to selectively obtain either unsaturated carboxylic acids or hydroxylactones in high yields from β-silyl cyclohexanones. Copyright
- Uyanik, Muhammet,Nakashima, Daisuke,Ishihara, Kazuaki
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p. 9093 - 9096
(2012/11/07)
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- Applications of a high performance platinum nanocatalyst for the oxidation of alcohols in water
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Nanoparticles of platinum (NP-Pt), have been synthesized by supporting high nuclearity anionic carbonyl cluster (Chini cluster) on a water soluble anion exchanger, and the performance of this material, 1, as an oxidation catalyst for alcohols in water has been studied. The E-factor for the synthesis of NP-Pt by this method has been calculated and compared with that of other NP-Pt recently reported in the literature. With 1 as a catalyst, oxidations of a variety of primary and secondary alcohols by dioxygen are achieved and high turnover numbers and selectivities are obtained. The performances of 1 in the oxidation of benzyl alcohol and 1-phenylethanol are compared with those of three other platinum catalysts. These are platinum nanoparticles 2 prepared by the hydrogen reduction of [PtCl6]2- supported on the same water soluble polymer, 5% Pt on carbon, and 5% Pt on alumina, designated as 3 and 4, respectively. 1 has been found to be considerably more active than 2-4 and also other reported water soluble platinum nanocatalysts. After many turnovers (～1000 and ～165 for benzyl alcohol and 1-phenyl ethanol, respectively) partial deactivation (～ 40%) is observed, but the deactivated catalyst can be fully regenerated by treatment with dihydrogen. The TEM data of fresh, deactivated and regenerated 1 show a correlation between the particle size and activity. A mechanism consistent with this and other experimental observations including XPS data is proposed.
- Maity, Prasenjit,Gopinath, Chinnakonda S.,Bhaduri, Sumit,Lahiri, Goutam Kumar
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experimental part
p. 554 - 561
(2010/04/23)
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- Total synthesis of amphidinolactone A and its absolute configuration
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Asymmetric synthesis of amphidinolactone A, a cytotoxic macrolide from the cultured dinoflagellate Amphidinium sp., has been accomplished. Absolute configuration of amphidinolactone A was concluded to be 1 from comparison of the NMR data and [α]D values of synthetic and natural amphidinolactone A.
- Hangyou, Masahiro,Ishiyama, Haruaki,Takahashi, Yohei,Kubota, Takaaki,Kobayashi, Jun'ichi
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body text
p. 1475 - 1477
(2009/06/08)
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- Bronsted base-modulated Regioselective Pd-catalyzed intramolecular aerobic oxidative amination of alkenes: Formation of seven-membered amides and evidence for allylic C-H activation
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A novel palladium-catalyzed intramolecular aerobic oxidative allylic C-H amination of olefins has been developed. Bronsted base can modulate the regioselectivity, favoring the formation of 7-membered rings. Mechanistic studies using deuterium-labeled substrates as probes support a rate-determining allylic C-H activation/irreversible reductive elimination pathway.
- Wu, Liang,Qiu, Shuifa,Liu, Guosheng
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supporting information; scheme or table
p. 2707 - 2710
(2009/10/10)
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- Stereoselective synthesis of rubrenoic and nor-rubrenoic acids
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The total stereoselective synthesis of (Z)-rubrenoic I (1a), (Z)-nor-rubrenoic I (17a), (E)-rubrenoic III (3b), and nor-(E)-rubrenoic III (30b) acids was achieved using Suzuki and Stille cross-coupling reactions from readily available starting materials.
- Sanchez, Lucina G.,Castillo, Elizabeth N.,Maldonado, Hortensia,Chavez, Daniel,Somanathan, Ratnasamy,Aguirre, Gerardo
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- Synthetic application of PVP-stabilized Au nanocluster catalyst to aerobic oxidation of alcohols in aqueous solution under ambient conditions
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Gold nanoclusters (φ = 1.3 nm) stabilized by poly(N-vinyl-2- pyrrolidone) (Au:PVP) were found to show a high catalytic activity toward the aerobic oxidation of alcohols. Various kinds of primary and secondary alcohols were converted to the corresponding carboxylic acids and ketones, respectively, in basic aqueous media at 300-360 K under air. Copyright
- Tsunoyama, Hironori,Tsukuda, Tatsuya,Sakurai, Hidehiro
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p. 212 - 213
(2008/02/04)
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- Highly reactive and chemoselective cleavage of allyl esters using an air- and moisture-stable [CpRu(IV)(π-C3H5)(2-quinolinecarboxylato)]PF6 catalyst
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A new catalytic process for allyl ester cleavage has been developed by using a robust cationic CpRu(IV) π-allyl complex of 2-quinolinecarboxylic acid that can be stored for over six months in air without any loss of catalytic activity. The deprotection of various alcohols and acids can be attained simply with high reactivity and chemoselectivity under mild conditions. Furthermore, with continuous removal of the low-boiling point coproduct, a turnover number of 1 000 000 can be achieved.
- Tanaka, Shinji,Saburi, Hajime,Murase, Takanori,Ishibashi, Yoshitaka,Kitamura, Masato
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p. 295 - 298
(2008/02/03)
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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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p. 2016 - 2019
(2007/10/03)
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- Isonitrile trapping reactions under thermolysis of alkoxyamines for the synthesis of quinolines
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An efficient tandem radical process comprising a thermal alkoxyamine homolysis, an isonitrile trapping reaction, a 5-exo-trig cyclization, and a homolytic aromatic substitution leads to substituted dihydroquinolines. Depending on the substituent R1, oxidation to dihydro-1H-cyclopenta- [b]quinolines (for R1 = aryl) or tautomerization to tetrahydro-1H-cyclopenta[b]quinolines (for R1 = CO2Me, CN) occurs. The heterocycles are obtained in moderate to good yields. Upon using microwave-induced heating, the reaction time can be shortened from 3 days to 30 min.
- Janza, Birgit,Studer, Armido
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p. 1875 - 1878
(2007/10/03)
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- In situ generation of o-lodoxybenzoic acid (IBX) and the catalytic use of it in oxidation reactions in the presence of oxone as a co-oxidant
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(Chemical Equation Presented) Catalytic use of o-iodoxybenzoic acid (IBX) in the presence of Oxone as a co-oxidant is demonstrated for the oxidation of primary and secondary alcohols in user- and eco-friendly solvent mixtures. Also demonstrated is the in situ (re)oxidation of 2-iodosobenzoic acid (IBA) and even commercially available 2-iodobenzoic acid (2IBAcid) by Oxone to IBX allowing one to use these less hazardous reagents, in place of potentially explosive IBX, as catalytic oxidants.
- Thottumkara, Arun P.,Bowsher, Michael S.,Vinod, Thottumkara K.
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p. 2933 - 2936
(2007/10/03)
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- Cp2ZrCl2-mediated three-component coupling reactions of CO2, ethylene (or alkynes), and electrophiles leading to carboxylic acid derivatives
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Zirconacycles 1 and 2 can be simply generated from Cp2ZrCl 2, EtMgBr, and an atmospheric pressure of CO2. The treatment of Cp2ZrCl2 with EtMgBr followed by exposure to CO2 generates zirconacycle 1, which can react with various electrophiles to give a variety of carboxylic acid derivatives. Unsaturated zirconacycles 2 can also generated from Cp2ZrCl2, EtMgBr, alkynes, and CO2. Complexes 2 react with electrophiles to give α,β-unsaturated acids stereoselectively.
- Yamashita, Kohei,Chatani, Naoto
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p. 919 - 922
(2007/10/03)
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- Process for the preparation of epsilon-caprolactam from a mixture comprising 6-aminocaproamide and/or oligomers
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The invention relates to a process for the preparation of ε-caprolactam from a mixture comprising 6-aminocaproamide and/or oligomers thereof, wherein in a first step 6-aminocaproamide and/or oligomers thereof is converted at a temperature of between 180 and 250°C into ammonia and 6-aminocaproic acid and/or oligomers thereof, with a separate or simultaneous removal of the ammonia, and in a subsequent step the 6-aminocaproic acid and/or oligomers thereof are converted into caprolactam at a temperature of between 250 and 400 °C.
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- Asymmetric photolysis of 2-phenylcycloalkanones with circularly polarized light: A kinetic model for magnetic field effects
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Magnetic field effects (MFE) on asymmetric photolysis involving a biradical intermediate have been investigated on a kinetic model where an intersystem crossing (ISC) of the intermediate is taken into account. Changes in the enantiomeric excesses (ee) of chiral substances with circularly polarized light (CPL) irradiation have been simulated, and the necessary conditions for observing the MFE were obtained. The asymmetric photolysis of racemic 2-phenylcycloalkanones (2-PCAs) with CPL has been carried out in both the presence and absence of a magnetic field. Since the anisotropy g factors of 2-PCAs are considerably large, the CPL-induced ee are achieved to a few percent after 90% decomposition though the MFE are not observed. The photolysis mechanism of 2-PCAs in an air-saturated solution has been also clarified. Triplet acyl-benzyl biradicals, formed via photochemical α-cleavage of 2-PCAs, react with O2 dissolved in the solution and result in the formation of acetophenone and alkenoic acids. The bimolecular reactions are diffusion-controlled and the rates are comparable to those of ISC to the singlet biradicals for all 2-PCAs. The recombination yields of the biradicals are sufficiently large. However, the biradical ISC rate shows little magnetic field dependence, which explains the absence of the MFE in this asymmetric photolysis.
- Kohtani, Shigeru,Sugiyama, Masahide,Fujiwara, Yoshihisa,Tanimoto, Yoshifumi,Nakagaki, Ryoichi
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p. 1223 - 1233
(2007/10/03)
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- Total Synthesis and Structural Refinement of the Cyclic Tripyrrole Pigment Nonylprodigiosin
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The first total synthesis of the cyclic prodigiosin derivative 4 is described, which constitutes a potential lead compound for the development of immunosuppressive agents. The key steps of this approach comprise a palladium-catalyzed Suzuki cross coupling reaction of the rather unstable pyrrole boronic acid derivative 17 with the electron rich pyrrolyl triflate 15 followed by a ring-closing metathesis reaction (RCM) of the resulting diene to form the macrocyclic ring of the target molecule. This transformation is best achieved by using the ruthenium indenylidene complex 21 as precatalyst. X-ray data of product 18·HCl thus formed suggest that the tautomeric form B properly describes the electron distribution within the heteroaromatic segment of this alkaloid, in which the central ring constitutes the azafulvene unit of the pyrrolylpyrromethene chromophore.
- Fuerstner, Alois,Grabowski, Jaroslaw,Lehmann, Christian W.
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p. 8275 - 8280
(2007/10/03)
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- Reactions of β-trimethylstannylcyclohexanones with peracids: Investigations into the stannyl-directed Baeyer-Villiger reaction
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The trimethylstannyl subsituent raises the migratory aptitude of a primary β-carbon to be above that of a not otherwise activated secondary or tertiary carbon. This is apparent from the exclusive formation of the alkene acids 9-11 from Baeyer-Villiger reaction of the β-stannyl cyclohexanones 3-5. The stereoelectronic requirements of the stannyl-directed Baeyer-Villiger reaction were investigated using the axial β-trimethylstannlcyclohexanone 20.
- Horvat, Sonia,Karallas, Panagoitis,White, Jonathan M.
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p. 2151 - 2154
(2007/10/03)
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- Fibrinogen receptor antagonists
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Fibrinogen receptor antagonists having the structure, for example, of STR1 for example STR2
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- Radical formation in the oxidation of 2,2′-azo-2-methyl-6-heptene by thianthrene cation radical
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Reaction of 2,2′-azo-2-methyl-6-heptene (1) with thianthrene cation radical perchlorate (Th?+ClO4-) in CH2Cl2 solution containing 2,6-di-tert-butyl-4-methylpyridine (DTBMP) gave a mixture of nine C8 hydrocarbons, namely, 1,1,2-trimethylcyclopentane (4, 2.2%), 6-methyl-1-heptene (5, 2.2%), 2-methyl-1,6-heptadiene (6, 9.8%), 2,2-dimethyl-1-methylenecyclopentane (7, 2.9%), 6-methyl-1,5-heptadiene (8, 39%), 3,3-dimethyl- (9, 7.6%), 4,4-dimethyl- (10, 11%), 1,2-dimethyl- (11, 5.4%), and 1,6-dimethylcyclohexene (12, 1.5%). The amounts of acyclic dienes (6, 8) fell and of cyclohexenes (9, 10) rose when DTBMP was omitted from or diminished in the solution. The results provide firm evidence (products 4, 5, and 7) for the formation of the 2-methyl-6-hepten-2-yl radical (2), although the major fate of 2 is its oxidation to the corresponding cation 13, the origin of the bulk of the other products.
- Chen, Tonghua,Shine, Henry J.
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p. 4716 - 4719
(2007/10/03)
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- Preparation of 2-(6-carboxyhexyl)- and 2-(6-methoxycarbonylhexyl)cyclopent-2-en-1-one using free radical reactions
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Two short and simple synthetic routes to the prostaglandin synthons 2-(6-carboxyhexyl)- and 2-(6-methoxycarbonylhexyl)cyclopent-2-en-1-one have been developed. The first is based on a cyclohexanone oxidative transformation with hydrogen peroxide and di-tert-butyl peroxide, the second on the free radical addition reaction of methyl 9-oxononanoate to acrylaldehyde diacylal.
- Ogibin,Starostin,Aleksandrov,Pivnitsky,Nikishin
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p. 901 - 903
(2007/10/02)
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- CERTAIN (ARYLSULFONAMIDO- AND IMIDAZOLYL-)-SUBSTITUTED CARBOXYLIC ACIDS AND DERIVATIVES THEREOF AND USE FOR SUPPRESSING THROMBOXANE ACTIVITY
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The present invention is concerned with compounds of formula I STR1 wherein A, B, M, R, Ar and Het are as defined in the specification, pharmaceutically acceptable ester and amide derivatives thereof; N-oxides thereof, tetrazole derivatives thereof, and s
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- Antiinflammatory leukotriene B4 analogs
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This invention encompasses novel analogs of Leukotriene B4 which are selected from a compound of formula I, B--C~C--CH2 C(M2)--C~C--Y--C(M1)--A, or formula II, B--C~C--CH2 C(M2)--C~C--P--R5 --A: wherein Y is: STR1 wherein P is: STR2 Patentable intermediates, process for making the novel analogs and intermediates and preparation of useful pharmacological agents comprising the analogs and intermediates are part of this invention.
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- Dispiro-1,2,4-trioxolanes by Ozonolysis of Cycloalkylidenecycloalkanes on Polyethylene
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Ozonolyses of symmetrical (1b-d) and of unsymmetrical cycloalkylidenecycloalkanes (8a, b) afforded the dispiro-1,2,4-trioxolanes 4b-d and 9a, b, respectively.Their thermal decompositions gave mixtures of the cyclic ketones (3) and lactones (6).Photolysis afforded in addition to 3 and 6 the cyclic anhydrides 13, which are isomeric with the corresponding disoiro-1,2,4-trioxolanes.
- Griesbaum, Karl,Krieger-Beck, Petra,Beck, Johannes
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p. 391 - 396
(2007/10/02)
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- Single Electron Transfer Mechanism in the Reaction of 1,3-Dithianyllithium and Alkyl Iodides
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The reaction between 2-lithio-1,3-dithiane and optically active (R)-2-iodooctane was found to proceed with complete inversion of configuration.This result suggests that the SN2 (rather than single electron transfer (SET)) mechanism is the preferred pathway for reaction between dithianyllithium and unhindered alkyl halides.When the neopentyl-type radical probe 5,5-dimethyl-6-iodo-1-hexene was used as the substrate halide, 6-11percent cyclized alkylated product was obtained.This result suggests that when the SN2 pathway is blocked, SET mechanisms become operative to some extent, at least with iodide as the halogen.The reaction of dithianyllithium and (R)-2-iodooctane and 5,5-dimethyl-6-iodo-1-hexene, with hexane as the solvent, proceeds under heterogeneous conditions to bring about complete racemization of the respective iodide.These results demonstrate for the first time that 2-lithio-1,3-dithiane can act as electron donor in reactions initiated by electron transfer to alkyl iodides.
- Juaristi, Eusebio,Jimenez-Vazquez, Hugo A.
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p. 1623 - 1630
(2007/10/02)
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- 1,3-dioxolane derivatives useful in the treatment of inflammation
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The present invention relates to compounds of the formula STR1 or a pharmaceutically acceptable salt thereof, wherein R is alkyl of 5 to 14 carbon atoms, alkenyl of 5 to 14 carbon atoms or alkynyl of 5 to 14 carbon atoms; R1 is lower alkylene o
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- A Facile Method for Synthesis of Three Carbon-Homologated Carboxylic Acid by Regioselective Ring-opening of β-Propiolactones with Organocopper Reagents
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Organocopper reagents, such as diorganocuprates, organocopper-tributylphosphine, and Grignard reagents in the presence of a copper (I) salt, reacted with β-propiolactones by regioselective β-carbon-oxygen fission to give 3-substituted propionic acids.Among these three kinds of organocopper reagents, diorganocuprate, especially halomagnesium cuprate gave the highest yields of the acids, which was remarkably observed in the ring-opening of sterically hindered β-propiolactones such as β-methyl- and α,β-dimethyl-β-propiolactones and also in the reactions using the organocopper reagents with vinyl and allyl substituents.The ring-opening of β-propiolactone was confirmed to proceed by SN2 pathway with predominant inversion of configuration of the β-carbon by using the reaction of cis-α,β-dimethyl-β-propiolactone with di-tert-butylcuprate to afford syn-2,3,4,4-tetramethylpentanoic acid.
- Kawashima, Masatoshi,Sato, Toshio,Fujisawa, Tamotsu
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p. 403 - 412
(2007/10/02)
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- New Routes to Heterocycles via Sulphenylation of Unsaturated Amides
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The reaction of manganese(III) acetate with diphenyl disulphide in dichloromethane-trifluoroacetic acid in the presence of N-allylacetamide, followed by hydrolysis, affords a vicinal hydroxy sulphide.Similarly, addition to N-allyltrifluoroacetamide affords hydroxy sulphide adducts, but with different regioselectivity.N-Allylbenzamide and other unsaturated benzamides under similar conditions give cyclic products, 4,5-dihydro-1,3-oxazoles.Homoallylic amides give 5,6-dihydro-4H-1,3-oxazines.Amides derived from pent-4-enylamine give substituted pyrrolidines by cyclisation through nitrogen, but N-hex-5-enylbenzamide gives only an acyclic adduct.Unsaturated carboxylic acids and unsaturated carboxamides are transformed in good yield into lactones under similar conditions.
- Samii, Zakaria K. M. Abd El,Ashmawy, Mohamed I. Al,Mellor, John M.
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p. 2517 - 2522
(2007/10/02)
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- DIELS-ALDER REACTIVITY OF PYRANOINDOL-3-ONES. PART 3. INTRAMOLECULAR DIELS-ALDER REACTIONS.
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Heating the 1-alkynylpyranoindol-3-ones (5), prepared from the alkynoic acids (3), results in intramolecular Diels-Alder reaction involving the indole-2,3-quinodimethane diene with subsequent extrusion of carbon dioxide to give the cycloalkacarbazoles (6).The pyranoindolones need not be isolated, since the 2-acylindol-3-ylacetic acids (8) undergo cyclodehydration and intramolecular Diels-Alder reaction when heated in an acidic anhydride as solvent.In contrast to the intramolecular Diels-Alder reaction involving the acetylenic compound (5a), the olefin (9) was a much poorer substrate.
- Moody, Christopher J.,Shah, Pritom,Knowles, Philip
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p. 3249 - 3254
(2007/10/02)
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- Vibrational Spectra of Potassium 4-Pentenoate and Potassium 5-Hexenoate and Conformational Change on Micellization
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Potassium 4-pentenoate (P4P) and potassium 5-hexenoate (P5H) have been synthesized and their infrared and Raman spectra were measured in the crystalline state and aqueous solutions.The two bands of the crystalline P4P at 623-625 and 558-560 cm-1 were assigned to the characteristic bands of skew and cis forms about the C-C single bond nearest to the C=C double bond, respectively.The intensity of the 623-625 cm-1 band in the infrared spectra increases at -170 deg C, compared to that of the 558-560 cm-1 band.For P5H the intensity of the 640-643 cm-1 band characteristic of skew intercreases at low temperature.From these observations it was concluded that the skew form in the crystalline P4P and P5H is stabilized at low temperature.On the basis of these observations and X-ray diffraction and Raman studies of unsaturated fatty acids by other workers, the following assumptions were made; the infrared bands of the crystalline P4P increasing in the intensity at -170 deg C and the corresponding Raman bands arise from the TS form, and those of P5H are due to the TTS form.On these assumptions, normal mode analysis was made for possible rotational isomers.The calculated results succesfully explain the vibrational bands of P4P and P5H.The Raman spectra of P4P anf P5H in aqueous solutions were measured at various concentrations.At higher concentration the TS form of P4P and the TTS form of P5H were found to be stabilized.The inflection in the plots of the relative Raman peak heights in the 1000-800 cm-1 region vs. the inverse concentrations is clearly observed.These observations show that micelle formation brings about the conformational change.
- Tsukamoto, Koji,Ohshima, Kunihiro,Taga, Keijiro,Okabayashi, Hirofumi,Matsuura, Hiroatsu
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p. 789 - 800
(2007/10/02)
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- A ONE STEP SYNTHESIS OF ω-HYDROXYACETYLENIC CARBOXYLIC ACIDS
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A convenient chemioselective method to prepare ω-hydroxyacetylenic carboxylic acids from unprotected ω-alkyn-1 ols and ω-bromo acids is described.
- Cossy, J.,Pete, J. P.
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p. 573 - 574
(2007/10/02)
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- PREPARATION OF TERMINAL ALKENIC ESTERS BY AN OXIDATIVE RADICAL REACTION
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A general method is described for the conversion of (mono)alkenic esters with the double bond at the nth C atom to terminal alkenic esters of (n-1) C atoms in length, with the double bond at n-2.Ozonolysis, either in methanol or in light petroleum, is followed by reaction with a mixture of ferrous and cupric salts.Methyl 10-undecenoate, methyl oleate (methyl (Z)-9-octadecenoate) and methyl erucate (methyl (Z)-13-docosenoate) were converted to methyl 8-nonenoate, methyl 7-ocotenoate and methyl 11-dodecenoate respectively.An improved preparation of 5-hexenoic acid is also described.
- Cardinale, G.,Laan, J. A. M.,Ward, J. P.
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p. 2899 - 2902
(2007/10/02)
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- Lithium or Bromomagnesium 1,4- and 1,5-Dilithioalkan-2-yloxides: Preparation and Synthetic Applications
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Treatment of chloromethyl 2- or 3-chloroalkyl carbinols with butyllithium and then lithium naphthalenide or with ethylmagnesium bromide and then powdered lithium leads to the formation of lithium or bromomagnesium dilithiothioalkoxides, respectively, which represent trianionic species.The bromomagnesium 1,ω-dilithio-2-alkoxides undergo immediate elimination of lithium bromide and magnesium oxide to give ω-lithio-1-alkenes.These latter organometallic compounds as well as the lithium dithioalkoxides react with various electrophiles to afford functionalized compounds.
- Barluenga, Jose,Fernandez, Jose R.,Yus, Miguel
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p. 977 - 979
(2007/10/02)
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- SMALL RING COMPOUNDS-XLI. CYCLOBUTENE CYCLOADDITIONS; SYNTHESIS AND REACTIVITY IN THE BICYCLOHEXAN-2-ONE SERIES
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Cyclobutene, prepared by base-induced elimination from tosyloxycyclobutane 19 undergoes cycloaddition with ethyl propiolate in the presence of AlCl3 to provide ethyl bicyclohex-2-ene-2-carboxylate 20.This cycloadduct at room temperature and in the presence of AlCl3 undergoes forbidden ring opening into ethyl cyclohexa-1,3-diene-2-carboxylate 21.The cycloaddition of cyclobutene with dichloroketene provides 3,3-dichlorobicyclohexan-2-one 24 and after reductive halogen removal the endo 3-chloro bicyclohexan-2-one 28 (the first study of this strained system).However, further dechlorination of 28 results in rearrangement and fragmentation reactions.
- Fadel, A.,Salauen, J.,Conia, J. M.
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p. 1567 - 1574
(2007/10/02)
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