- Visible-Light Mediated Tryptophan Modification in Oligopeptides Employing Acylsilanes
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A method for the selective tryptophan modification and labelling of tryptophan-containing peptides is described. Photoirradiation of acylsilanes generates reactive siloxycarbenes which undergo H?N-insertion into the indole moiety of tryptophan to give stable silyl protected hemiaminals. This method is successfully applied to chemically modify various tryptophan containing oligopeptides. The method enables the selective introduction of alkynes to peptides that are eligible for further alkyne-azide click chemistry. In addition, the dansyl fluorophore can be conjugated to a peptide using this approach.
- Reimler, Jannik,Studer, Armido
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p. 15392 - 15395
(2021/10/04)
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- Chemoselective Amide-Forming Ligation Between Acylsilanes and Hydroxylamines Under Aqueous Conditions
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We report the facile amide-forming ligation of acylsilanes with hydroxylamines (ASHA ligation) under aqueous conditions. The ligation is fast, chemoselective, mild, high-yielding and displays excellent functional-group tolerance. Late-stage modifications of an array of marketed drugs, peptides, natural products, and biologically active compounds showcase the robustness and functional-group tolerance of the reaction. The key to the success of the reaction could be the possible formation of the strong Si?O bond via a Brook-type rearrangement. Given its simplicity and efficiency, this ligation has the potential to unfold new applications in the areas of medicinal chemistry and chemical biology.
- Deng, Xingwang,Zhou, Guan,Tian, Jing,Srinivasan, Rajavel
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supporting information
p. 7024 - 7029
(2020/12/29)
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- Visible-Light-Induced Catalyst-Free Carboxylation of Acylsilanes with Carbon Dioxide
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Intermolecular carbon-carbon bond formation between acylsilanes and carbon dioxide (CO2) was achieved by photoirradiation under catalyst-free conditions. In this reaction, siloxycarbenes generated by photoisomerization of the acylsilanes added to the C═O bond of CO2 to give α-ketocarboxylates, which underwent hydrolysis to afford α-ketocarboxylic derivatives in good yields. Control experiments suggest that the generated siloxycarbene is likely to be from the singlet state (S1) of the acylsilane and the addition to CO2 is not in a concerted manner.
- Fan, Zhengning,Yi, Yaping,Chen, Shenhao,Xi, Chanjuan
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supporting information
p. 2303 - 2307
(2021/04/05)
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- Ruthenium-Catalyzed Brook Rearrangement Involved Domino Sequence Enabled by Acylsilane-Aldehyde Corporation
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A ruthenium-catalyzed [1,2]-Brook rearrangement involved domino sequence is presented to prepare highly functionalized silyloxy indenes with atomic- and step-economy. This domino reaction is triggered by acylsilane-directed C-H activation, and the aldehyde controlled the subsequent enol cyclization/Brook Rearrangement other than β-H elimination. The protocol tolerates a broad substitution pattern, and the further synthetic elaboration of silyloxy indenes allows access to a diverse range of interesting indene and indanone derivatives.
- Lu, Xiunan,Zhang, Jian,Xu, Liangyao,Shen, Wenzhou,Yu, Feifei,Ding, Liyuan,Zhong, Guofu
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supporting information
p. 5610 - 5616
(2020/07/24)
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- Oxidative [1,2]-Brook Rearrangements Exploiting Single-Electron Transfer: Photoredox-Catalyzed Alkylations and Arylations
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Oxidative [1,2]-Brook rearrangements via hypervalent silicon intermediates induced by photoredox-catalyzed single-electron transfer have been achieved, permitting the formation of reactive radical species that can engage in alkylations and arylations.
- Deng, Yifan,Liu, Qi,Smith, Amos B.
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p. 9487 - 9490
(2017/07/24)
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- Facile deprotection of dithioacetals by using a novel 1,4-benzoquinone/cat. NaI system
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The combination of 1,4-benzoquinone and a catalytic amount of NaI was found to be effective for the deprotection of dithioacetals. The reactions proceeded efficiently under mild, near-neutral reaction conditions, producing a wide range of aryl and alkyl aldehydes and ketones generally in high yields with good functional group compatibility. The method developed therefore represents a general, facile, and highly applicable approach for deprotecting dithioacetals.
- Inamoto, Kiyofumi,Yamada, Tetsuya,Kato, Sei-Ichi,Kikkawa, Shoko,Kondo, Yoshinori
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p. 9192 - 9199
(2013/10/01)
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- Palladium-catalyzed fluoride-free cross-coupling of intramolecularly activated alkenylsilanes and alkenylgermanes: Synthesis of tamoxifen as a synthetic application
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We have demonstrated that intramolecular hypercoordination of a carboxylic acid is a powerful activation strategy for the palladium-catalyzed cross-coupling reaction of trialkyl(vinyl)silanes and trialkyl(vinyl)germanes under fluoride-free conditions. Z-β-Trialkylsilyl- and Z-β- trialkylgermylacrylic acids, synthesized stereoselectively by olefination with ynolates, are highly stable and useful reagents for cross-coupling with a variety of aryl iodides to provide tetrasubstituted olefins possessing different carbon substituents in a stereocontrolled and diversity-oriented manner. An application to a stereoselective synthesis of (Z)-tamoxifen is also reported. Copyright
- Matsumoto, Kenji,Shindo, Mitsuru
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p. 642 - 650
(2012/05/04)
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- Photochemically promoted transition metal-free cross-coupling of acylsilanes with organoboronic esters
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Intermolecular carbon-carbon bond formation between acylsilanes and organoboronic esters was achieved by photoirradiation under almost neutral, transition metal-free conditions. In this reaction, siloxycarbenes generated by photoisomerization of acylsilanes reacted with boronic esters to give the formal B-C bond insertion intermediates, which underwent unique rearrangement to afford the cyclic α-alkoxyboronic esters. Acidic treatment of the resulting crude products under air furnished the cross-coupled ketones in good yields.
- Ito, Kazuta,Tamashima, Hiroto,Iwasawa, Nobuharu,Kusama, Hiroyuki
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supporting information; experimental part
p. 3716 - 3719
(2011/05/14)
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- A simple method for mild oxidation of α-hydroxysilanes to provide aroylsilanes
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Potassium permanganate supported onto alumina in hexane-water is a good oxidizing agent to convert α-hydroxysilanes into acylsilanes. This mild oxidation afforded aroylsilanes having electron-donating groups attached to the aromatic ring, in 70-86% yield.
- Patrocinio,Moran
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p. 2457 - 2461
(2007/10/03)
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- Synthesis of aryl and alkyl acylsilanes using trimethyl(tributylstannyl)silane
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Palladium catalyzed coupling of acid chlorides and trimethyl(tribuhfistannyl)silane proves to be a convenient method for the preparation of both aromatic and aliphatic acylsilanes.
- Geng, Feng,Maleczka Jr., Robert E.
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p. 3113 - 3114
(2007/10/03)
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- Reactions of Acyl Silanes with Fluoride Ion
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Acyl silanes react with fluoride ion to give products arising either from intermediates equivalent to acyl anions or from rearrangement involving alkyl group migration from the silicon atom to the carbonyl carbon atom, depending upon acyl silane structure and reaction conditions.
- Page, Philip C. Bulman,Rosenthal, Stephen
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p. 2351 - 2363
(2007/10/02)
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- Silylative Decarbonylation: A New Route to Arylsilanes
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A new synthetic procedure for the preparation of aromatic chlorosilanes via the palladium-catalyzed reaction of methylchlorodisilanes and aromatic acid chloride is described.The silylative decarbonylation process is solventless, can utilize low metal catalyst loadings (500-1000 ppm Pd), is carried out under moderate conditions (145 deg C), and selectively gives aromatic chlorosilanes in good yield, generally 60-85percent.The procedure is tolerant of a variety of aromatic substituents, for example, alkyl, halo, nitro, cyano, imide, acid anhydride, etc., and the synthesis ofseveral new substituted aromatic chlorosilanes containing benzoyl chloride and phthalic anhydride moieties is described.Chloromethyldisilane starting reagents are available from the direct reaction of methyl chloride and silicon, making this methodology an attractive synthetic route to functionalized aromatic chlorosilanes.
- Rich, Jonathan D.
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p. 5886 - 5893
(2007/10/02)
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- PREPARATION OF SUBSTITUTED BENZOYLTRIMETHYLSILANES BY THE PALLADIUM-CATALYZED SILYLATION OF SUBSTITUTED BENZOYL CHLORIDES WITH HEXAMETHYLDISILANE
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A direct preparative route to benzoyltrimethylsilane has been found by the reaction of benzoyl chloride with hexamethyldisilane in the presence of a specified palladium(II) complex as catalyst.
- Yamamoto, Keiji,Suzuki, Shigeaki,Tsuji, Jiro
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p. 1653 - 1656
(2007/10/02)
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- THE CONVERSION OF α,α-DIBROMOBENZYLSILANES INTO ACYLSILANES ON SILICA GEL
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Acylsilanes may be prepared in high yield by treating α,α-dibromobenzylsilanes with silica gel
- Degl'Innocenti, Alessandro,Walton,David R. M.,Seconi, Giancarlo,Pirazzini, Graziella,Ricci, Alfredo
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p. 3927 - 3928
(2007/10/02)
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