- Green and Efficient: Iron-Catalyzed Selective Oxidation of Olefins to Carbonyls with O2
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A mild and operationally simple iron-catalyzed protocol for the selective aerobic oxidation of aromatic olefins to carbonyl compounds is described. Catalyzed by a Fe(III) species bearing a pyridine bisimidazoline ligand at 1 atm of O2, α- and β-substituted styrenes were cleaved to afford benzaldehydes and aromatic ketones generally in high yields with excellent chemoselectivity and very good functional group tolerance, including those containing radical-sensitive groups. With α-halo-substituted styrenes, the oxidation took place with concomitant halide migration to afford α-halo acetophenones. Various observations have been made, pointing to a mechanism in which both molecular oxygen and the olefinic substrate coordinate to the iron center, leading to the formation of a dioxetane intermediate, which collapses to give the carbonyl product. (Chemical Equation).
- Gonzalez-De-Castro, Angela,Xiao, Jianliang
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supporting information
p. 8206 - 8218
(2015/07/15)
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- Development of a mild and efficient protocol for the protection and O-alkylation of allyl alcohols
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An efficient, pyridine-free protocol has been developed for the protection of the 3°-allyl alcohol of oxindole using a mild base, such as potassium carbonate, under microwave irradiation conditions. The methodology has been tested with a variety of substrates and protecting group reagents, which provides a clean and good yield of the desired products within a short reaction time. the Partner Organisations 2014.
- Selvakumar, Kodirajan,Prasath Lingam, Kandapalam Arun,Luxmi Varma, Rama Varma
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p. 36538 - 36543
(2014/11/07)
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- Molecular iodine in isopropenyl acetate (IPA): a highly efficient catalyst for the acetylation of alcohols, amines and phenols under solvent free conditions
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Iodine in isopropenyl acetate (IPA) is a highly efficient catalyst for the acetylation of a variety of alcohols, phenols and amines under solvent free conditions. Primary, secondary, tertiary alcohols, amines and mono to polyhydroxy phenols and anilines with electron donating or withdrawing substituents can be easily acetylated in good to excellent yield at 85-90 °C.
- Ahmed, Naseem,van Lier, Johan E.
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p. 5345 - 5349
(2007/10/03)
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- Synthesis of anhydrides from acyl halides and zinc carboxylates under aprotic conditions
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Synthesis of symmetric as well as unsymmetrical carboxylic acid anhydrides from zinc carboxylates and acid chlorides under aprotic conditions in high yields is reported.
- Pasha,Rizwana
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p. 420 - 421
(2007/10/03)
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- A facile synthesis of acid anhydrides
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A facile synthesis of symmetric and unsymmetric acid anhydrides using phase-transfer catalysis is described. By this method different types of anhydrides can be obtained in high yields under mild conditions even on microscale levels.
- Dubey,Kumar, R. Vinod
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- Quinolone carboxylic acid derivatives and process for preparing the same
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The present invention relates to novel quinolone carboxylic acid derivatives having useful antibacterial activities of formula (I): STR1 wherein, R1, R2, and R3, which may be the same or different, are each hydrogen or a h
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- Modification of the photochemical reactivity of α,β-diacetoxystilbene by adsorption onto a Fe3+-doped sepiolite: Comparison with the direct and 2,4,6-triphenylpyrylium-sensitized photolyses
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Photolysis of α,β-diacetoxystilbene (1) adsorbed onto a Fe3+-doped sepiolite (Fe-Sp) leads to benzoic acid (3), 9,10-diacetoxyphenanthrene (5), diphenic anhydride (6), and benzil (7). While compounds 3, 5 and 6 are also observed in the direct irradiation of 1 in hexane solution, diketone 7 is formed under electron transfer conditions using 2,4,6-triphenylpyrylium tetrafluoroborate as photosensitizer. These results strongly suggest that formation of benzil (7) in the photolysis of 1 on Fe-Sp involves the intermediacy of 1+·, generated by single electron transfer from excited 1 to the iron active sites of the clay. In contrast to the unsubstituted stilbene, reactivity of 1+· with ground state molecular oxygen has been established by cyclic voltammetry through the current intensity decrease of the oxidation peak of 1 in the presence of oxygen. Finally, the thermodynamic feasibility of a direct electron transfer pathway between excited 1* and oxygen leading to the formation of a dioxetane intermediate is discussed.
- Baldovi,Garcia,Miranda,Primo,Soto,Vargas
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p. 8113 - 8120
(2007/10/02)
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- Synthesis and Thermolysis of Ketal Derivatives of 3-Hydroxy-1,2-dioxolanes
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3--3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (2), 3-methoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (3), and 3-acetoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (4) were synthesized from the corresponding 3-hydroxy-1,2-dioxolane (1a) under basic conditions. 3-Acetoxy-4,4-dimethyl-3,5,5-triphenyl-1,2-dioxolane (5) was also synthesized via this approach.Under acidic conditions, 3-hydroxy-1,2-dioxolane 1a underwent quantitative decomposition to phenol and 3,3-dimethyl-2,4-pentanedione.This competing degradation was dependent on the nature of the substituents at position-5.Methyl groups at position-5 slowed the degradative rearrangement whereas phenyl groups favored it. 3-Methoxy- and 3-(allyloxy)-4,4,5,5-tetramethyl-3-phenyl-1,2-dioxolanes (6, 7) were synthesized under acidic conditions from the appropriate 1,2-dioxolane precursors and the corresponding alcohols.At 60 deg C, derivatized 1,2-dioxolanes 2-7 were found to be more stable than the corresponding 3-hydroxy-1,2-dioxolanes.The first order rate constants for the thermolysis of 1,2-dioxolanes 2-7 were determined.Product studies showed that thermolysis of 2-5 yielded pairs of ketones and derivatized carboxylic acids.In addition to R-group migration products, an acetoxy migration product was observed for the thermolysis of 4.Thermolysis of 6 at 60 deg C in benzene yielded methyl benzoate and pinacolone, quantitatively.Thermolysis of 7 yielded products analogous to those for 6.No evidence for internal trapping of radicals by the carbon-carbon double bond of the allyloxy group in 7 was found.The thermolysis appeared to proceed with peroxy bond homolysis as the rate-determining step.Subsequent β-scissions of the intermediate 1,5-oxygen diradical with interesting rearrangements that show a high preference for alkyl vs phenyl migration account for the observed product distributions.The results suggest that the β-scission/rearrangement mechanism may not be concerted but rather stepwise to yield 1,3-diradical and carbonyl fragments.
- Baumstark, A. L.,Vasquez, P. C.,Chen, Y.-X.
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p. 6692 - 6696
(2007/10/02)
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- Novel quinolone carboxylic acid derivatives and process for preparing the same
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The present invention relates to novel quinolone carboxylic acid derivatives of formula (I): wherein,R1, R2 and R3,which may be the same or different, are each hydrogen or a halogen atom, or a lower alkyl group or a lower
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- Acyloxy-1,2,4-trioxolanes by Dry Ozonolyses of Vinylesters on Polyethylene
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By dry ozonolyses on polyethylene, the vinylic esters 5a-5e afforded the corresponding ozonides 8a-8e, while 5f gave ozonide 8e.Ozonide 8a gave among other products 16 and 17 by thermal decomposition, and 21 by decomposition on silica gel. - Key Words: Acyloxy-1,2,4-trioxolanes / Ozonolysis, dry / Polyethylene / Vinylic esters
- Griesbaum, Karl,Volpp, Willi,Huh, Tae-Seong,Jung, In Chan
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p. 941 - 944
(2007/10/02)
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- THERMAL TRANSFORMATIONS OF OXAZOLE ENDOPEROXIDES: REARRANGEMENTS, FRAGMENTATIONS AND METHANOL ADDITIONS
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Oxazole endoperoxides 1 carrying a phenyl group at C-2 rearrange to triacylamines 3; those carrying a hydrogen atom at C-2 undergo a fragmentation into 1:1 mixtures of nitriles (or HCN) 4 and anhydrides 5, whereas methyl substitution at C-2 gives rise to competition between these two modes of reaction.Methanol addition to 1 leads to 4-methoxy-5-hydroperoxides 6 which easily transform into methyl esters 7 and diacylamines 8.
- Gollnick, Klaus,Koegler, Sigrid
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p. 1007 - 1010
(2007/10/02)
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- Water-Soluble Acylating Agents: Preparation of 2-Acylthio-1-alkylpyridinium Salts and Acylation of Phenols, Acids, and/or Amines with These Salts in an Aqueous Phase
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Reaction of phenols, amines, and acids with 2-benzoylthio-1-methylpyridinium chloride prepared in situ from benzoyl chloride and 1-methyl-2(1H)-pyridinethione, afforded the corresponding benzoyl derivatives in good yields.In the reaction of p-nitrophenol, even catalytic amount of 1-methyl-2(1H)-pyridinethione proved to be effective.Similar reactions of p-nitrophenol with isobutyryl chloride and acetyl chloride in the presence of 1-methyl-2(1H)-pyridinethione afforded p-nitrophenyl isobutyrate and p-nitrophenyl acetate in 63 and 44percent yields, respectively. 2-Benzoylthio-, 2-acetylthio-, and 2-isobutyrylthio-1-ethylpyridinium tetrafluorobora tes were prepared by treatment of the corresponding 2-acylthiopyridines with triethyloxonium tetrafluoroborate.These pyridinium salts also acted as acylating agents in an aqueous phase. some competitive reactions of 2-aminoethanol and phenols with 2-benzoylthio-1-methylpyridinium chloride were also investigated.
- Sakakibara, Tohru,Watabe, Yukie,Yamada, Masahide,Sudoh, Rokuro
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p. 247 - 254
(2007/10/02)
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- PHASE MANAGED ORGANIC SYNTHESIS 2. A NEW POLYMER ASSISTED SYNTHESIS OF ACID ANHYDRIDES.
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A solid-phase copolymer of 4-vinylpyridine is shown to be a highly effective reagent/catalyst for the synthesis of acid anhydrides from mixtures containing equimolar quantities of carboxylic acid and acid chlorides.The process may be carried out in batch or column mode.
- Fife, Wilmer K.,Zhang, Zhi-dong
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p. 4933 - 4936
(2007/10/02)
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- Diozonolyses of Acyclic Conjugated Dienes in Methanol
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In the diozonolyses of isoprene (1a), 2-methyl-3-phenyl-1,3-butadiene (1b), 2,3-diphenyl-1,3-butadiene (26), and 2,3,4,5-tetramethyl-2,4-hexadiene (30) in methanol subsequent reactions of the primary cleavage products afforded abnormal products, which arose from cleavage of both the double bonds and the single bonds of the diene systems.In addition, the diozonolyses of 26 and 30 gave products, in which one of the double bonds of the respective diene system has been epoxidized.The mode of formation of the abnormal cleavage products has been elucidated by the ozonolysis of the intermediate products, viz. of α,β-unsaturated methoxyhydroperoxides and of α,β-unsaturated carbonyl compounds.
- Griesbaum, Karl,Zwick, Gerhard
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p. 229 - 243
(2007/10/02)
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- Synthesis, Thermal Stability, and Chemiluminescence Properties of Bisdioxetanes Derived from p-Dioxines
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By elimination of methanol from 2,5-dimethoxy-1,4-dioxanes and 2,3-dihydro-2-methoxy-1,4-dioxines on treatment with p-toluenesulfonic acid in acetic anhydride, the new tetrakis(4-methoxyphenyl)-, tetrakis(4-chlorophenyl)-, tetra-p-tolyl-, and 2,5-dimethyl-3,6-diphenyl-1,4-dioxines (1) were prepared in good yields.Photosensitized singlet oxygenation of these 1,4-dioxines 1 afforded the corresponding bisdioxetanes 2, the 1,2-diketones, and the enediol diesters 7.Thermal decomposition of the bisdioxetanes 2 yielded the corresponding anhydrides 4 essentially quantitatively.During the thermolysis of 1,6-dimethyl-3,8-diphenyl-2,4,5,7,9,10-hexaoxatricyclo3,6>decane (2f) appreciable amounts of (3R,4S)-3-acetoxy-4-(benzoyloxy)-4-methyl-3-phenyl-1,2-dioxetane (3f) were detected.The bisdioxetanes 2 and monodioxetane 3f exhibited similar thermal stabilities, the free energies of activation (ΔG%) at 298 K falling within 25.5 + 1.5 kcal/mol.The singlet excitation yields (ΦS) ranged between 0.003 and 0.03percent and the triplet excitation yields (ΦT) between 9.5 and 71.5percent.Despite the favorable energy balance, it is concluded that no higher excited states of anhydride 4f are produced during the thermolysis of bisdioxetane 2f.On thermal activation, the bisdioxetanes decompose by sequential cleavage of the two dioxetane rings.
- Adam, Waldemar,Platsch, Herbert,Schmidt, Ernst
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p. 4385 - 4403
(2007/10/02)
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- " Mediator Methodology" for the Synthesis of Peptides in a Two-Polymeric System
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Abstract: A novel methodology is described for a potential automated self-controlled synthesis of peptides.The method is based on transferring an N-protected amino acid from one insoluble polymer (donor) such as a polymeric o-nitrophenyl ester (a "bank" of active ester) to an insoluble polymer-bound amino acid (acceptor),with the aid of a soluble mediator molecule (shadchan)2 The method gives high yields of pure peptides by garanteeing stoichiomeric supply of the active ester and allowing self monitoring.When the polymer-bound (dimethylamino)pyridinium salts, the condensation reaction was expended to also include sulfonation and particularly phosphorylation reactions.
- Shai, Yechiel,Jacobson, Kenneth A.,Patchornik, Abraham
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p. 4249 - 4252
(2007/10/02)
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- FOUR-MEMBERED RING PEROXIDE HETEROCYCLES : PHOTOCHEMISTRY THROUGH THE BACKDOOR
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The unusal property of four-membered ring peroxide heterocycles (1,2-dioxetanes) to produce electronically excited carbonyl fragments on thermal decomposition is discussed.The synthetic tools for the preparation of such labile substances and the analytic methods for assessing excitation yields are covered.Using the complete series of methylated derivatives of the parent 1,2-dioxetane, their thermal stability and excited state production is rationalized in terms of a modified diradical mechanism.With the helf of bisdioxetanes, it is shown that generation of upper excited states is improbable, despite the fact that sufficient energy is available for this purpose.Attachment of dioxetanes to biomolecules via mild esterifications provides interesting opportunities for photobiological exploration.
- Adam, Waldemar,Baader, Wihelm J.,Babatsikos, Chrisostomos,Schmidt, Ernst
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p. 605 - 618
(2007/10/02)
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- PREPARATION OF ACYL(CARBOXYLATO)NICKAL AND -PALLADIUM COMPLEXES M(COR) (OCOR')L2 (M = Ni, Pd) AND REVERSIBLE REDUCTIVE ELIMINATION OF CARBOXYLIC ANHYDRIDES, RCOOCOR'
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Acyl(carboxylato)nickel(II) and -palladium(II) complexes, M(COR) (OCOR')L2 2 are prepared by 1:1 reactions of MR(OCOR')L2 1 with CO at -78 deg C, whereas similar reactions in the presence of excess CO at room temperature afford the reductive elimination products, RCOOCOR'.Acid anhydrides add oxidatively to an Ni())-complex to afford a complex of the type 2.
- Komiya, Sanshiro,Yamamoto, Akio,Yamamoto, Takakazu
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p. 193 - 196
(2007/10/02)
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- OXYGEN ATOM TRANSFER REACTION. THE REACTION OF CARBONYL COMPOUNDS WITH DIOXYGEN COMPLEXES
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The reaction of peroxobis(triphenylphosphine)platinum with benzil or benzoic anhydride gave benzoic anhydride or benzoyl peroxide respectively.The scope of the above reactions is described.
- Aida, Shun'ichi,Ohta, Hiroyuki,Kamiya, Yoshio
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p. 1639 - 1642
(2007/10/02)
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- Reaction of Diazonium Salts with Transition Metals. 6. Preparation of Mixed Acid Anhydrides from Arenediazonium Salts and Sodium Carboxylates under Palladium(0) Catalysis
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The palladium(0)-catalyzed reaction of arenediazonium tetrafluoroborates with carbon monoxide and sodium carboxylates in acetonitrile at 25 deg C gave mixed acid anhydrides, ArCOOCOR (Ar = 3-Me-Ph, 4-Me-Ph, 2-MeO-Ph, 4-Br-Ph, 4-I-Ph, 3-NO2-Ph, 4-NO2-Ph, and Ph; R = H, Me, Et, t-Bu, and Ph) in good yields.Homoaromatic acid anhydrides, (ArCO)2O, were obtained by heating of ArCOOCOMe at 100-120 deg C under vacuum.ArCOOCO-t-Bu can be utilized to obtain the corresponding arenecarboxamides by the reaction with some amines.
- Kikukawa, Kiyoshi,Kono, Kiyoshi,Nagira, Kazuhiko,Wada, Fumio,Matsuda, Tsutomu
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p. 4413 - 4416
(2007/10/02)
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- NOVEL TRANSFORMATION OF ARENEDIAZONIUM SALTS TO ACID ANHYDRIDES UNDER PALLADIUM CATALYSIS
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Palladium catalyzed reaction of arenediazonium salts, carbon monoxide and sodium carboxylates gave mixed anhydrides, wich in turn could be converted to aromatic acid anhydrides in good yields.
- Kikukawa, Kiyoshi,Kono, Kiyoshi,Nagira, Kazuhiko,Wada, Fumio,Matsuda, Tsutomu
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p. 2877 - 2878
(2007/10/02)
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