- S-(2-pyridinyl)-1,1,3,3-tetramethylthiouronium hexafluorophosphate. A new reagent for the synthesis of 2-pyridinethiol esters
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(Matrix presented) A new thiouronium-based reagent for the synthesis of 2-pyridinethiol esters under non-nucleophilic conditions from the corresponding carboxylic acids was developed. The resulting procedure enables the preparation of previously unavailable α,β-unsaturated 2-pyridinethiol esters as well as their aliphatic and aromatic counterparts.
- Scardovi, Noemi,Garner, Philip P.,Protasiewicz, John D.
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- Cobalt-catalyzed acylation-reactions of (hetero)arylzinc pivalates with thiopyridyl ester derivatives
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A cobalt-catalyzed acylation reaction of various primary, secondary and tertiary alkyl, benzyl and (hetero)aryl S-pyridyl thioesters with (hetero)arylzinc pivalates is reported. The thioesters were prepared directly from the corresponding carboxylic acids under mild conditions, thus tolerating sensitive functional groups. Acylations of α-chiral S-pyridyl esters proceeded with very high stereoretention leading to optically enriched α-chiral ketones.
- Lutter, Ferdinand H.,Grokenberger, Lucie,Hofmayer, Maximilian S.,Knochel, Paul
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p. 8241 - 8245
(2019/09/19)
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- Ketones from Nickel-Catalyzed Decarboxylative, Non-Symmetric Cross-Electrophile Coupling of Carboxylic Acid Esters
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Synthesis of the C?C bonds of ketones relies upon one high-availability reagent (carboxylic acids) and one low-availability reagent (organometallic reagents or alkyl iodides). We demonstrate here a ketone synthesis that couples two different carboxylic acid esters, N-hydroxyphthalimide esters and S-2-pyridyl thioesters, to form aryl alkyl and dialkyl ketones in high yields. The keys to this approach are the use of a nickel catalyst with an electron-poor bipyridine or terpyridine ligand, a THF/DMA mixed solvent system, and ZnCl2 to enhance the reactivity of the NHP ester. The resulting reaction can be used to form ketones that have previously been difficult to access, such as hindered tertiary/tertiary ketones with strained rings and ketones with α-heteroatoms. The conditions can be employed in the coupling of complex fragments, including a 20-mer peptide fragment analog of Exendin(9–39) on solid support.
- Wang, Jiang,Cary, Brian P.,Beyer, Peyton D.,Gellman, Samuel H.,Weix, Daniel J.
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supporting information
p. 12081 - 12085
(2019/08/12)
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- An Improved N-Acylation of 1 H-Benzotriazole Using 2,2′-Dipyridyl?-di?-sulfide and Triphenylphosphine
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A novel path has been developed for the conversion of carboxylic acids into the corresponding N-acylbenzotriazoles by using 2,2′-dipyridyl disulfide/PPh 3 in anhydrous dichloromethane in the presence of 1 H-benzotriazole. Mild reaction conditio
- Singh, Anoop S.,Agrahari, Anand K.,Mishra, Nidhi,Singh, Mala,Tiwari, Vinod K.
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p. 470 - 476
(2019/01/10)
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- Photoinduced Dynamics of Bis-dipyrrinato-palladium(II) and Porphodimethenato-palladium(II) Complexes: Governing Near Infrared Phosphorescence by Structural Restriction
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Although superficially similar, the bis-dipyrrinato-palladium(II) complex 1 and the bridged porphodimethenato-palladium(II) complex 2 possess dramatically different structures in the ground state (proved by X-ray structure analysis) and in the singlet and
- Riese, Stefan,Holzapfel, Marco,Schmiedel, Alexander,Gert, Ingo,Schmidt, David,Würthner, Frank,Lambert, Christoph
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supporting information
p. 12480 - 12488
(2018/10/25)
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- Two-photon oxygen sensing with quantum dot-porphyrin conjugates
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Supramolecular assemblies of a quantum dot (QD) associated to palladium(II) porphyrins have been developed to detect oxygen (pO2) in organic solvents. Palladium porphyrins are sensitive in the 0-160 Torr range, making them ideal phosphors for i
- Lemon, Christopher M.,Karnas, Elizabeth,Bawendi, Moungi G.,Nocera, Daniel G.
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supporting information
p. 10394 - 10406
(2013/10/01)
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- Synthesis of urea picket porphyrins and their use in the elucidation of the role buried solvent plays in the selectivity and stoichiometry of anion binding receptors
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(Chemical Equation Presented) The synthesis of α,α-5,10-diurea and α,α,α-5,10,15-triurea picket porphyrins are detailed in this report. In previous reports, these porphyrins, along with α,α,α,α-5,10,15,20-tetraurea picket porphyrin, were used to demonstra
- Calderon-Kawasaki, Kenichi,Kularatne, Sumith,Yue, Hu Li,Noll, Bruce C.,Scheidt, W. Robert,Burns, Dennis H.
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p. 9081 - 9087
(2008/04/05)
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- Metal complexation of 1-acyldipyrromethanes and porphyrins formed therefrom
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A first aspect of the invention is a method of making a porphyrin-metal complex, comprising: (a) providing a first reagent selected from the group consisting of 1-acyldipyrromethanes, 1-acyldipyrrins, dipyrromethane-1-carbinols 1,9-diacyldipyrromethanes and 1,9-diacyldipyrrins; and then (b) condensing the first reagent with either itself (in the case of 1-acyldipyrromethanes, 1-acyldipyrrins, and dipyrromethane-1-carbinols) or a dipyrromethane (in the case of 1,9-diacyldipyrromethanes and 1,9-diacyldipyrrins) in a reaction mixture comprising a solvent and a second reagent selected from the group consisting of palladium and copper complexes to produce the porphyrin-metal complex (with the metal being palladium or copper). In preferred embodiments of the foregoing, the reaction mixture further comprises a base such as KOH or NaH.
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Page/Page column 7; 19
(2008/06/13)
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- Direct synthesis of palladium porphyrins from acyldipyrromethanes
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(Chemical Equation Presented) Palladium porphyrins are valuable photosensitizers and luminescent agents in biology and materials chemistry. New methodology is described wherein a 1-acyldipyrromethane is converted into the palladium chelate of a trans-A2B2 porphyrin via a one-flask reaction. The reaction entails self-condensation of the 1-acyldipyrromethane in refluxing ethanol containing KOH (5-10 mol equiv) and Pd(CH3CN)2Cl2 (0.6 mol equiv) exposed to air. This direct route to palladium porphyrins is more expedient than the four steps of the traditional synthesis: (1) reduction of the 1-acyldipyrromethane; (2) acid-catalyzed condensation; (3) oxidation of the porphyrinogen intermediate; and (4) metal insertion. The new synthesis requires neither acid nor DDQ and formally entails only a 2e- + 2H+ oxidation overall versus the traditional multistep synthesis which requires a 2e- + 2H + reduction per each 1-acyldipyrromethane (4e- + 4H + overall) followed by a 6e- + 6H+ oxidation. The analogous reaction of a 1,9-diacyldipyrromethane and a dipyrromethane also gives the palladium porphyrin. Seven palladium porphyrins have been prepared in yields of 25-57%. The direct route also can be used with Cu(OAc) 2·H2O to give the copper porphyrin albeit in low yield. In summary, this methodology readily affords palladium porphyrins directly from acyldipyrromethanes.
- Sharada, Duddu S.,Muresan, Ana Z.,Muthukumaran, Kannan,Lindsey, Jonathan S.
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p. 3500 - 3510
(2007/10/03)
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- Efficient synthesis of monoacyl dipyrromethanes and their use in the preparation of sterically unhindered trans-porphyrins
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The condensation of an aldehyde with a dipyrromethane bearing a sterically unhindered aryl substituent at the 5-position typically results in low yield and a mixture of porphyrin products derived from acidolytic scrambling. We have developed a concise nonscrambling synthesis of such trans-porphyrins that takes advantage of the availability of multigram quantities of dipyrromethanes. This route involves the selective monoacylation of the dipyrromethanes with a pyridyl thioester, reduction of the monoacyl dipyrromethane to the corresponding carbinol, and self- condensation of the carbinol to form the porphyrin. The monoacylation procedure has wide scope as demonstrated by the preparation of a set of 15 diverse monoacyl dipyrromethanes in good yield at the multigram scale. The dipyrromethanecarbinol self-condensation reaction is extremely rapid (3 min) under mild room-temperature conditions and affords the trans-porphyrin in 16- 28% yield. Analysis by laser-desorption mass spectrometry (LD-MS) of samples from the crude reaction mixture revealed no scrambling within the limit of detection (1 part in 100). The self-condensation is compatible with a range of electron-withdrawing or -releasing substituents as well as substituents for building block applications (TMS-ethyne, ethyne, iodo, ester). The absence of any detectable scrambling in the self-condensation enables a simple purification. The synthesis readily affords gram quantities of pure, sterically unhindered trans-porphyrins in a process involving minimal chromatography.
- Rao, Polisetti Dharma,Littler, Benjamin J.,Geier III, G. Richard,Lindsey, Jonathan S.
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p. 1084 - 1092
(2007/10/03)
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- Kinetics of Intramolecular Alkyl Radical Attack on Sulfur in Disulfides and Thioesters
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The 4-(alkyldithio)butyl radicals 8a and c, and the 4-(phenyldithio)butyl radical 8b, generated from the corresponding esters of N-hydroxypyridine-2(1H)-thione, undergo fast exo-cyclisation by SHi attack at sulfur.Similarly, the 5-(alkyldithio)pentyl radical 8d undergoes 1,6-ring formation.The rate constants for cyclisation were determined by photolysis of the radical precursors in the presence of appropriate thiols.Butyl and pentyl radicals bearing ω-acetylthio or ω-benzoylthio substituents also undergo ring closure but much more slowly.The kinetics of these intramolecular SH2 reactions are discussed and compared with those for the intermolecular attack of hexyl radicals on diphenyl disulfide and on dibutyl disulfide.
- Beckwith, Athelstan L. J.,Duggan, Sandhya A. M.
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p. 1509 - 1518
(2007/10/02)
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- THE GENERATION AND REACTIVITY OF OXYGEN CENTERED RADICALS FROM THE PHOTOLYSIS OF DERIVATIVES OF N-HYDROXY-2-THIOPYRIDONE
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Oxgen centered radicals, formed by the photolysis of derivatives of N-hydroxy-2-thiopyridone, have been trapped by vinyl ethers.In the case of the benzoyloxy radical, smooth deoxygenation is effected by IIIP compounds.Evidence for the formation of the dimethyltbutylsilyloxy and of the hydroxy radical is also presented.
- Barton, Derek H. R.,Jaszberenyi, Joseph Cs.,Morrell, Andrew I.
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p. 311 - 314
(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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- Facile Conversions of Carboxylic Acids into Amides, Esters, and Thioesters Using 1,1'-Oxalyldiimidazole and 1,1'-Oxalyldi(1,2,4-triazole)
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Aliphatic, aromatic, and heteroaromatic carboxylic acids react with 1,1'-oxalyldiimidazole (1) or 1,1'-oxalyldi(1,2,4-triazole) (2) in acetonitrile for 40 min at 40 degC to give the corresponding 1-acylazole intermediates (11), which promptly undergo aminolysis and alcoholysis to form amides (13) including dipeptides (14), esters (16), and thioesters (19).These findings show that both 1 and 2 can be utilized as condensing reagents for the synthesis of carboxylic acid derivatives.Keywords --- 1,1'-oxalyldiimidazole; 1,1'-oxalyldi(1,2,4-triazole); 1,1'-carbonyldiimidazole; 1-acylazole; condensing reagent; amidation; esterification; dipeptide; aminolysis; alcoholysis
- Kitagawa, Tokujiro,Kuroda, Hiroko,Sasaki, Hideaki,Kawasaki, Koichi
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p. 4294 - 4301
(2007/10/02)
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- A MILD METHOD FOR THE SYNTHESIS OF 2-KETOPYRROLES FROM CARBOXYLIC ACIDS
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A mild method for the synthesis of 2-ketopyrroles from carboxylic acids via 2-pyridylthiolesters and pyrrylmagnesium chloride is described.
- Nicolaou, K. C.,Claremon, D. A.,Papahatjis, D. P.
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p. 4647 - 4650
(2007/10/02)
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- Utilisation of Sulphur-containing Leaving Groups. Part 2. Monitored Reduction of Carboxylic Acids into Alcohols or Aldehydes via 3-Acylthiazolidine-2-thiones by Sodium Borohydride or Di-isobutylaluminium Hydride
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3-Acylthiazolidine-2-thiones (2) have been prepared by three methods, and treated with di-isobutylaluminium hydride or sodium borohydride to give aldehyde or alcohol in high yield, respectively.The original yellow colour disappears when reduction is finished, enabling the reaction to be monitored.The high reactivity of the carbonyl group in amide (2) was briefly discussed.
- Nagao, Yoshimitsu,Kawabata, Kohji,Seno, Kaoru,Fujita, Eiichi
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p. 2470 - 2473
(2007/10/02)
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