- Cys–Cys and Cys–Lys Stapling of Unprotected Peptides Enabled by Hypervalent Iodine Reagents
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Easy access to a wide range of structurally diverse stapled peptides is crucial for the development of inhibitors of protein-protein interactions. Herein, we report bis-functional hypervalent iodine reagents for two-component cysteine-cysteine and cysteine-lysine stapling yielding structurally diverse thioalkyne linkers. This stapling method works with unprotected natural amino acid residues and does not require pre-functionalization or metal catalysis. The products are stable to purification and isolation. Post-stapling modification can be accessed via amidation of an activated ester, or via cycloaddition onto the formed thioalkyne group. Increased helicity and binding affinity to MDM2 was obtained for a i,i+7 stapled peptide.
- Ceballos, Javier,Grinhagena, Elija,Sangouard, Gontran,Heinis, Christian,Waser, Jerome
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supporting information
p. 9022 - 9031
(2021/03/16)
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- Gold(i)-catalyzed Nicholas reaction with aromatic molecules utilizing a bifunctional propargyl dicobalt hexacarbonyl complex
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A benchtop-stable reagent for the catalytic Nicholas reaction was developed. By combining a propargyl dicobalt hexacarbonyl cluster with an ortho-alkynylbenzoate unit and a fluorous tag, introduction of a propargyl hexacarbonyl complex on various aromatic compounds having acid- or base-sensitive functional groups becomes possible by using a gold(i) catalyst. In addition, the presence of a fluorous tag facilitates convenient separation of the target products from byproducts.
- Okamura, Toshitaka,Fujiki, Shogo,Iwabuchi, Yoshiharu,Kanoh, Naoki
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supporting information
p. 8522 - 8526
(2019/10/02)
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- Divergent Syntheses of (Z)-3-Alkylideneisobenzofuran-1(3 H)-ones and 1 H-Isochromen-1-ones by Copper-Catalyzed Cycloisomerization of 2-Alkynylbenzoic Acids in Ionic Liquids
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The cycloisomerization of readily available 2-alkynylbenzoic acids 1 in ionic liquids (ILs) as recyclable reaction media has been studied under the catalytic action of CuCl2. With substrates bearing an aryl group on the triple bond, a mixture o
- Mancuso, Raffaella,Pomelli, Christian S.,Chiappetta, Piera,Gioia, Katia F.,Maner, Asif,Marino, Nadia,Veltri, Lucia,Chiappe, Cinzia,Gabriele, Bartolo
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p. 6673 - 6680
(2018/06/01)
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- Divergent syntheses of iodinated isobenzofuranones and isochromenones by iodolactonization of 2-alkynylbenzoic acids in ionic liquids
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The regiochemical outcome of the iodolactonization of 2-alkynylbenzoic acids, carried out at 100 °C in ionic liquids (ILs) as unconventional solvents and with molecular iodine as the iodine source, in the absence of external bases, was found to be strongl
- Mancuso, Raffaella,Pomelli, Christian C.,Malafronte, Francesco,Maner, Asif,Marino, Nadia,Chiappe, Cinzia,Gabriele, Bartolo
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supporting information
p. 4831 - 4841
(2017/07/10)
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- Palladium NNC Pincer Complex as an Efficient Catalyst for the Cycloisomerization of Alkynoic Acids
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A two-step (nucleophilic substitution/palladation by oxidative addition) sequence provides a high-yielding access to a non-symmetrical palladium NNC pincer complex. A number of terminal and internal alkynoic acids with different substitution patterns at the α- and β-positions are regio- and diastereoselectively cycloisomerized to the corresponding exocyclic enol lactones in the presence of exceedingly low amounts of the latter palladium complex, so that unprecedented turnover numbers and frequencies ranging from 1,000,000 to 700,000 and from 41,667 to 9722 h?1, respectively, are achieved. The optimized protocol, based on the use of a catalytic amount of triethylamine as base, allows an easy real-time monitoring of the reaction by NMR spectroscopy. Several pieces of evidence in favor of the direct participation of the above pincer complex as the catalyst of the reaction have been gathered from kinetic and poisoning experiments. (Figure presented.).
- Conde, Nerea,SanMartin, Raul,Herrero, María Teresa,Domínguez, Esther
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supporting information
p. 3283 - 3292
(2016/10/21)
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- A reaction-based sensing scheme for gold species: Introduction of a (2-ethynyl)benzoate reactive moiety
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To alleviate side reactions identified in an N-propargyl-rhodamine lactam sensing system, we devised the novel reaction-based sensing scheme for gold species based on the alkynophilicity. A fluorescein (2-ethynyl)benzoate underwent Au(III)-promoted ester
- Seo, Hyewon,Jun, Mi Eun,Ahn, Kyo Han,Egorova, Olga A.,Lee, Kyung-Ha,Kim, Kyong-Tai
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p. 5062 - 5065,4
(2012/12/13)
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- On homogeneous gold/palladium catalytic systems
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Two substrates containing an aryl iodide and an allenoate ester were prepared and the goldinduced cycloisomerisation to vinylgold(I) species and their proto-deauration as well as the intramolecular palladium-catalysed cross-coupling reactions were investigated. Switching to catalytic amounts of gold and palladium and stoichiometric amounts of silver did indeed furnish the product of a cycloisomerisation/ intramolecular cross-coupling. Control experiments revealed that silver cannot substitute for gold or palladium in these reactions, but a different palladium catalyst in a different oxidation state also afforded the cycloisomerisation/intramolecular crosscoupling products in only slightly reduced yields. By ICP analysis the palladium was shown to contain gold only at the sub-ppm level. This shows how carefully results obtained with such systems have to be interpreted. Then a series of allylic and benzylic o-alkynylbenzoates were investigated in gold-and palladium-catalysed reactions. For esters of benzyl alcohol and cinnamyl alcohol no palladium co-catalyst was needed for the conversion. All reagents were thoroughly checked for palladium traces by ICP analysis in order to thoroughly exclude a gold/palladium cocatalysis. Optimisation of the gold complex, counter ion and solvent showed that gold(I) isonitrile precatalysts and silver triflate as activator in dioxane are suitable to convert a number of substrates with aryl, alkyl and even cyclopropyl substituents. Crossover experiments proved an intermolecular allyl transfer.
- Hashmi, A. Stephen K.,Lothschuetz, Christian,Doepp, Rene,Ackermann, Martin,De Buck Becker, Janosc,Rudolph, Matthias,Scholz, Christian,Rominger, Frank
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supporting information; experimental part
p. 133 - 147
(2012/04/10)
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- Cycloisomerization of aromatic homo and bis-homopropargylic alcohols via catalytic ru vinylidenes: Formation of benzofurans and isochromenes
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Ru-catalyzed cycloisomerizations of aromatic homo- and bis-homopropargylic alcohols effectively afford benzofurans and isochromenes. These processes proved to be chemo- and regioselective (5-, and 6-endo cyclizations) derived from key Ru vinylidene intermediates. The presence of an amine/ammonium base-acid pair is crucial for the catalytic cycle.
- Varela-Fernandez, Alejandro,Gonzalez-Rodriguez, Carlos,Varela, Jesus A.,Castedo, Luis,Saa, Carlos
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supporting information; experimental part
p. 5350 - 5353
(2009/12/30)
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- Cycloisomerization of γ- and δ-acetylenic acids catalyzed by gold(I) chloride
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We have developed a gold(I)-catalyzed intramolecular cyclization of γ- and δ-alkyne acids in mild conditions yielding various alkylidene lactones. Whereas a slight electronic effect of the R group was observed on the regioselectivity, bulky substituents o
- Marchal, Estelle,Uriac, Philippe,Legouin, Béatrice,Toupet, Lo?c,Weghe, Pierre van de
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p. 9979 - 9990
(2008/02/13)
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- Solid-phase synthesis of an A-B loop mimetic of the Cε3 domain of human IgE: Macrocyclization by Sonogashira coupling
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The solid-phase synthesis of a cyclic peptide containing the 21-residue epitope found in the A-B loop of the Cε3 domain of human immunoglobulin E has been carried out. The key macrocyclization step to form the 65-membered ring is achieved in ~15% yield vi
- Spivey, Alan C.,McKendrick, John,Srikaran, Ratnasothy,Helm, Birgit A.
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p. 1843 - 1851
(2007/10/03)
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- Dimetallation of phenylacetylene. Synthesis of ortho-susbtituted derivatives of phenylacetylene, benzoselenophene and benzotellurophene
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Phenylacetylene can be dimetallated in two ways. o-K-C6H4-CC-Li is formed by treating phenylacetylene at -70 deg C with two equivalents of butyllithium and one equivalent of potassium tert-butoxide in a mixture of tetrahydrofuran and hexane.The dimetallation with BuLi*N,N,N',N'-tetramethylethanediamine (TMEDA) affords a mixture of about 15percent (m + p)-Li-C6H4-CCLi and 85percent o-LiC6H4-CC-Li.Ortho-K-C6H4-CC-Li can be transformed into the dilithio or di-Grignard derivatives by addition of anhydrous lithium bromide or magnesium bromide etherate.Reaction of the dilithio derivative with elemental selenium and tellurium, followed by successive addition of tert-butyl alcohol and hexamethylphosphoric triamide (HMPT), gives benzoselenophene and benzotellurophene in good yields.Regiospecific functionalization of the nucleus via dimetal derivatives succeeds in the case of alkylation, halogenation, sulfenylation and acylation (with dimethylformamide and dimethylacetamide).Trimethylchlorosilane, chloromethyl methyl ether, aldehydes and ketones do not however react regiospecifically.
- Brandsma, L.,Hommes, H.,Verkruijsse, H. D.,Jong, R. L. P. de
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p. 226 - 230
(2007/10/02)
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