- Spiroketal Formation by Cascade Oxidative Dearomatization: An Approach to the Phorbaketal Skeleton
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Addition of PhI(OAc)2 to phenols that have meta-linked hydroxy ketones results in cascade oxidative dearomatizing spirocyclization to give tricyclic spiroketals. This framework is found in the phorbaketal family of natural products.
- Shirley, Harry J.,Bray, Christopher D.
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Read Online
- NFSI/KF mediated mild and chemoselective interconversion of aryl TBDMS ethers to their benzene sulfonate
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A one pot protocol for the transformation of aryl TBDMS ethers to corresponding benzene sulfonate esters using NFSI (N-flurobenzenesulfonimide)/KF is described. In situ generation of benzenesulfonyl fluoride directs chemoselective cleavage of aryl silyl ethers over alkyl silyl ethers. Electron withdrawing substituent's on aryl ring provided better yield than donating groups. Protecting groups and sensitive functionalities are well tolerated in this methodology. Thus, commercially available inexpensive reagents, mild reaction conditions and step economy are the advantages of this method.
- Dond, Bharat D.,Thore, Shivaji N.
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supporting information
(2020/02/06)
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- Diversity Oriented Clicking (DOC): Divergent Synthesis of SuFExable Pharmacophores from 2-Substituted-Alkynyl-1-Sulfonyl Fluoride (SASF) Hubs
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Diversity Oriented Clicking (DOC) is a unified click-approach for the modular synthesis of lead-like structures through application of the wide family of click transformations. DOC evolved from the concept of achieving “diversity with ease”, by combining classic C?C π-bond click chemistry with recent developments in connective SuFEx-technologies. We showcase 2-Substituted-Alkynyl-1-Sulfonyl Fluorides (SASFs) as a new class of connective hub in concert with a diverse selection of click-cycloaddition processes. Through the selective DOC of SASFs with a range of dipoles and cyclic dienes, we report a diverse click-library of 173 unique functional molecules in minimal synthetic steps. The SuFExable library comprises 10 discrete heterocyclic core structures derived from 1,3- and 1,5-dipoles; while reaction with cyclic dienes yields several three-dimensional bicyclic Diels–Alder adducts. Growing the library to 278 discrete compounds through late-stage modification was made possible through SuFEx click derivatization of the pendant sulfonyl fluoride group in 96 well-plates—demonstrating the versatility of the DOC approach for the rapid synthesis of diverse functional structures. Screening for function against MRSA (USA300) revealed several lead hits with improved activity over methicillin.
- Barrow, Andrew S.,Cheng, Yunfei,Gialelis, Timothy L.,Giel, Marie-Claire,Kitamura, Seiya,Li, Gencheng,Moses, John E.,Ottonello, Alessandra,Sharpless, K. Barry,Smedley, Christopher J.,Wolan, Dennis W.
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supporting information
p. 12460 - 12469
(2020/06/10)
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- Continuous flow solvent free organic synthesis involving solids (reactants/products) using a screw reactor
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Here we report for the first-time various organic transformations such as aldol condensation, oxidation, nucleophilic substitutions, protection, acylations and coupling reactions using a mechanochemical approach at a controlled temperature using a single synthesis platform. Almost minimal solvents or solvent-free conditions are used, making it a very efficient and clean synthesis of various products. A jacketed screw reactor when operated at different temperatures (0 °C to 160 °C) and over a range of rotation speeds for changing the residence time (15 s-300 s) helped to achieve maximum conversion. This approach is also extended to the synthesis using substrates having different substitutions, heterocycles and steric hindrance.
- Sharma, Brijesh M.,Atapalkar, Ranjit S.,Kulkarni, Amol A.
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supporting information
p. 5639 - 5646
(2019/10/22)
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- Overcoming solid handling issues in continuous flow substitution reactions through ionic liquid formation
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Substitutions such as acylations, arylations, and alkylations are some of the most commonly run reactions for building complex molecules. However, the requirement of a stoichiometric base to scavange acid by-products creates significant challenges when operating in continuous flow due to solid handling issues associated with precipitating base·HX salts. We present a general and simple strategy to overcome these solid handling issues through the use of acid scavenging organic bases that generate low- to moderate-melting ionic liquids upon protonation. The application of these bases towards the most commonly run substitutions are demonstrated, enabling reactions to be run in flow without requiring additional equipment, specific solvents, or dilute reaction conditions to prevent clogging.
- Kashani, Saeed,Sullivan, Ryan J.,Andersen, Mads,Newman, Stephen G.
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supporting information
p. 1748 - 1753
(2018/04/30)
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- Tert-Butyldimethylsilyl Amine (TBDMS-NH2): A Mild and Green Reagent for the Protection of Benzyl Alcohols, Phenols, and Carboxylic Acids under Solvent-Free Conditions
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Herein, we present the use of the tert-butyldimethylsilyl amine (TBDMS-NH2) as a silylating reagent for phenols, benzyl alcohols, and carboxylic acids. Unlike other silyl protection reactions, this reported process with TBDMS-NH2 does not involve the form
- Duczynski, Jeremy A.,Fuller, Rebecca,Stewart, Scott G.
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p. 1172 - 1179
(2016/10/13)
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- The effect of solvent accessible surface on Hammett-type dependencies of infinite dilution 29Si and 13C NMR shifts in ring substituted silylated phenols dissolved in chloroform and acetone
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Infinite dilution 29Si and 13C NMR chemical shifts were determined from concentration dependencies of the shifts in dilute chloroform and acetone solutions of para substituted O-silylated phenols, 4-R-C6H4-O-SiR′2R″ (R = Me, MeO, H, F, Cl, NMe2, NH2, and CF3), where the silyl part included groups of different sizes: dimethylsilyl (R′ = Me, R″ = H), trimethylsilyl (R′ = R″ = Me), tert-butyldimethylsilyl (R′ = Me, R″ = CMe3), and tert-butyldiphenylsilyl (R′ = C6H5, R″ = CMe3). Dependencies of silicon and C-1 carbon chemical shifts on Hammett substituent constants are discussed. It is shown that the substituent sensitivity of these chemical shifts is reduced by association with chloroform, the reduction being proportional to the solvent accessible surface of the oxygen atom in the Si-O-C link. Copyright
- Blechta, Vratislav,Sabata, Stanislav,Sykora, Jan,Hetflejs, Jiri,Soukupova, Ludmila,Schraml, Jan
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experimental part
p. 128 - 134
(2012/08/07)
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- ANTIBACTERIAL COMPOUNDS AND METHODS OF USING SAME
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Embodiments of the present invention provide novel antibacterials that target penicillin-binding proteins or other important cellular targets. Methods for inhibiting growth (reproduction, etc.) of bacteria using compounds described herein are also provided. Various embodiments exhibit activity against gram positive bacteria, such as certain strains of Entercoccus and Staphylococcus aureus.
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Page/Page column 11
(2010/11/03)
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- ANTIBACTERIAL COMPOUNDS AND METHODS OF USING SAME
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Embodiments of the present invention provide novel antibactehals that target penicillin-binding proteins or other important cellular targets. Methods for inhibiting growth (reproduction, etc.) of bacteria using compounds described herein are also provided. Various embodiments exhibit activity against gram positive bacteria, such as certain strains of Entercoccus and Staphylococcus aureus.
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Page/Page column 27
(2009/05/29)
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- Iodine-promoted silylation of alcohols with silyl chlorides. Synthetic and mechanistic studies
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An efficient silylating system for 1°, 2°, and 3° alcohols, consisting of a silyl chloride/N-methylimidazole/iodine, was developed. Synthetic and mechanistic aspects of this new reagent system, and particularly the role of iodine were investigated in detail using 1H NMR spectroscopy.
- Bartoszewicz, Agnieszka,Kalek, Marcin,Stawinski, Jacek
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p. 8843 - 8850
(2008/12/21)
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- Activation of silylphosphines by diethyl azodicarboxylate: Novel silylation of alcohols
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A novel activation mode of silylphosphines and an application of that to silylation of alcohols were described. Silylphosphines were found to be instantly activated by means of DEAD and PPTS to form reactive silyl cation equivalents. By using the activate
- Hayashi, Minoru,Matsuura, Yutaka,Watanabe, Yutaka
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p. 1409 - 1411
(2007/10/03)
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- A novel and efficient method for the silylation of alcohols with methallylsilanes catalyzed by Sc(OTf)3
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Reaction of alcohols with methallylsilanes in the presence of a catalytic amount of Sc(OTf)3 provides efficiently the corresponding alkyl silyl ethers. By using microencapsulated (MC) Sc(OTf)3, which can be easily recovered and reused, yields of alkyl silyl ethers are improved and the work-up process after completion of the reaction is considerably simplified. (C) 2000 Elsevier Science Ltd.
- Suzuki,Watahiki,Oriyama
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p. 8903 - 8906
(2007/10/03)
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- Facile methods for the direct conversions of aryl acetates into the corresponding methoxymethyl ethers or silyl ethers
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Direct conversion of aryl acetates into aryl methoxymethyl ethers or aryl trialkylsilyl ethers was readily accomplished by treatment with methoxymethyl bromide or trialkylsilyl trifluoromethanesulfonate, respectively, in the presence of sodium methoxide.
- Oriyama, Takeshi,Noda, Kojiro,Sugawara, Satomi
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p. 2217 - 2223
(2007/10/03)
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- Mixed Methyl Silyl Ketals of Quinones: Their Preparation via Anodic Oxidation and Their Chemistry
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Anodic oxidation of tert-butyldimethylsilyl and tert-butyldiphenylsilyl derivatives of p-methoxyphenols affords quinone bisketals containing the uncommon alkyl silyl ketal unit.Acid hydrolysis of these quinone bisketals affords monoketals derived from hyd
- Stern, Alan,Swenton, John S.
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p. 2763 - 2768
(2007/10/02)
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