Sulfonated Graphene as a Sustainable Catalyst for Environmentally Benign Preparation of Benzylidene Acetals of Carbohydrates
Synlett DOI: 10.1055/a-2166-0400 A clean and efficient method has been developed for the introduction of benzylidene acetals into carbohydrate derivatives catalyzed by sulfonated graphene at room temperature. Yields were excellent in each case. The catalyst can be reused several times without much decrease in reactivity. [...] Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals: Table of contents | Abstract | Full text (Source: Synlett)
Source: Synlett - October 11, 2023 Category: Chemistry Authors: Rabha, Padmashri Sharma, Anjali Panchadhayee, Rajib Tags: letter Source Type: research
Solvent Selection in the Detritylation Reaction for the Solid-Phase Synthesis of Oligonucleotides
This study examined the choice of solvent in the detritylation reaction for solid-phase oligonucleotide synthesis. In addition to being chemically inert under detritylation conditions, such a solvent should not bind with acid used in this reaction. These considerations explained the only two choices of solvent currently used in the detritylation reaction: dichloromethane and toluene. Other solvents, such as ethyl acetate, acetonitrile, THF, and nitromethane are shown by NMR spectroscopy to bind with trichloroacetic acid. Therefore, these are undesirable solvents for the detritylation reaction, confirmed by solid-phase synt...
Source: Synlett - October 11, 2023 Category: Chemistry Authors: Li, Quanjian Sanghvi, Yogesh S. Yan, Hongbin Tags: letter Source Type: research
A Complementary Route for Alkene –Arene para-Cycloadditions by Visible-Light-Promoted Triplet Sensitization of Allenamides
Synlett DOI: 10.1055/a-2136-3947 The synthetic relevance of bicyclo[2.2.2]octadienes is witnessed by their successful application in various chemical domains, promoting a recurrent interest in the concise assembly of these bridged bicycles. Seminal examples of strategies to craft these compounds are presented, together with more-recent applications that exploit visible light. In this context, a general intramolecular method for the para-cycloaddition of an allenamide arm onto simple aryl rings is highlighted. [...] Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals: Table of cont...
Source: Synlett - October 9, 2023 Category: Chemistry Authors: Serafino, Andrea Maestri, Giovanni Tags: synpacts Source Type: research
A Simple and Powerful tert-Butylation of Carboxylic Acids and Alcohols
Synlett DOI: 10.1055/a-2161-9689 A simple and safe tert-butylation reaction was developed. Treatment of various free amino acids with 1.1 equivalents of bis(trifluoromethanesulfonyl)imide in tert-butyl acetate directly afforded tert-butyl esters with free amino groups quickly and in good yields. In addition, various carboxylic acids and alcohols without amino groups were converted into tert-butyl esters and ethers, respectively, in high yields in the presence of small catalytic amounts of bis(trifluoromethanesulfonyl)imide. All tert-butylation reactions of free amino acids, carboxylic acids, and alcohols proceeded much fas...
Source: Synlett - October 9, 2023 Category: Chemistry Authors: Ogasa, Chie Kayano, Kimika Namba, Kosuke Tags: letter Source Type: research
Visible-Light-Induced Oxidative Generation of o-Quinone Methides for Inverse-Electron-Demand [4+2] Cycloaddition Reactions
Synlett DOI: 10.1055/a-2158-8648 Organophotoredox-catalyzed oxidative generation of o-quinone methides (o-QMs) for inverse-electron-demand [4+2] cycloaddition reactions has been developed. One-electron oxidation of 2-(sulfanylmethyl)phenols by thioxanthylium photoredox catalyst generated o-QMs, which reacted with various styrenes to produce chromanes with high regioselectivity. This reaction offers a valuable approach for in situ generating o-QMs via one-electron oxidation process under irradiation with mild green light. [...] Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals: T...
Source: Synlett - October 9, 2023 Category: Chemistry Authors: Nohara, Shoya Iwai, Suguru Yamaguchi, Naoya Asada, Yosuke Kamiyama, Yusuke Tanaka, Yuta Tanaka, Kenta Hoshino, Yujiro Tags: cluster Source Type: research
Construction of Vicinal Stereocenters via Asymmetric Cyanosilylation
Conclusion [...] Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals: Table of contents | Abstract | Full text (Source: Synlett)
Source: Synlett - October 5, 2023 Category: Chemistry Authors: Huang, Zhongxing Tags: synpacts Source Type: research
Linked PDF of Table of Contents
Synlett 2023; 34: V- DOI: 10.1055/s-0042-1751622 Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals: Table of contents (Source: Synlett)
Source: Synlett - October 5, 2023 Category: Chemistry Tags: table of contents Source Type: research
Trimethylsilyl Azide Promoted Shono Oxidation of N,N-Dialkyl Amides
Synlett DOI: 10.1055/a-2159-4847 An alkoxylation of N,N-dialkyl amides by the Shono reaction has been developed that offers a simple and efficient way to access N-adjacent-carbon-substituted amides. TMSN3 plays an essential role in this transformation and permits the reaction to proceed with a broad substrate scope under mild conditions. This reaction proceeds at a lower current compared with the classical method and it affords the products in up to 91% yield. A possible mechanism is proposed based on control experiments. [...] Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle in Thieme eJournals: ...
Source: Synlett - October 4, 2023 Category: Chemistry Authors: Luo, Wenlin Zhang, Ruixing Xu, Qi Zheng, Shengyu Yang, Junpeng Liu, Meixia Guo, Shengmei Cai, Hu Tags: letter Source Type: research
Labeling of Highly Reactive Tetrazines using [18F]SuFEx
Synlett DOI: 10.1055/a-2147-9303 Pretargeted imaging is an emerging technique to study the in vivo biodistribution of nanomedicines. Currently, the tetrazine ligation is considered the most promising bioorthogonal reaction for pretargeting. Recently, Zheng et al. described an ultrafast late-stage radiolabeling of tetrazines based on sulfur 18F-fluoride exchange click chemistry ([18F]SuFEx). However, bispyridyl and H-tetrazines—the most promising structures for in vivo pretargeted applications—cannot be labeled using the proposed reaction conditions as they lead to decomposition of the tetrazine core. Here, we report im...
Source: Synlett - October 4, 2023 Category: Chemistry Authors: Battisti, Umberto M. M üller, Marius Garc ía-Vázquez, Rocío Herth, Matthias Manfred Tags: cluster Source Type: research
Intramolecular Asymmetric Cyclopropanation Using Air-Stable Alkylboronic Esters
Synlett DOI: 10.1055/a-2158-8752 The preparation of polysubstituted bicyclo[3.1.0]hexanes starting from air-stable substituted pent-4-en-1-ylboronic acid esters has been investigated. The method involves a Matteson homologation with LiCHCl2, leading to 1-chlorohex-5-en-1-ylboronic acid ester intermediates. The subsequent intramolecular cyclopropanation step was performed in a one-pot process. With pinacol boronic esters, the cyclopropanation step was either performed thermally at 140 °C or at 70 °C after in situ transesterification to form a catechol boronic ester. This last approach is suitable for the preparation of en...
Source: Synlett - September 28, 2023 Category: Chemistry Authors: Vedani, Luca Gn ägi-Lux, Manuel D énès, Fabrice Renaud, Philippe Tags: letter Source Type: research
DBU-Mediated Dimerization: Facile Access to 9,9 ′-Bifluorenylidenes and Isoindigos
Synlett DOI: 10.1055/a-2158-7980 The present work describes the 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)-promoted self-dimerization of 9-chlorofluorenes and 3-chlorooxindoles for the preparation of the corresponding 9,9′-bifluorenylidene and isoindigo derivatives in moderate to good yields of 29–97%. The reactions proceed readily in a short reaction time under mild and metal-free conditions. Scale-up syntheses (5.0 mmol) of selected 9,9′-bifluorenylidene derivatives proceed in decent yields, highlighting the synthetic utility of the reported protocol. [...] Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, ...
Source: Synlett - September 28, 2023 Category: Chemistry Authors: Purahong, Nitchakan Hongthong, Sakchai Chotsaeng, Nawasit Kuhakarn, Chutima Meesin, Jatuporn Tags: letter Source Type: research
A Combination of Computational and Experimental Studies to Correlate Electronic Structure and Reactivity of Donor –Acceptor Singlet Carbenes
Synlett DOI: 10.1055/a-2153-6819 Most of the reactivities of donor–acceptor (D–A) singlet carbenes are similar to metal carbenoids. However, the lone pair at the carbenoid carbon, coordinated with metal, is free in D–A carbene thereby making it nucleophilic as well. Herein, DFT-optimized structural features of D–A carbene has been investigated and is compared with rhodium carbenoid. It was observed that, when a D–A carbene reacts with cyclic-1,3-diones in different ethereal solvents, it is the lone pair at the sp2
orbital of the carbene that abstracts the proton from the enol form (of the cyclic-1,3-diones...
Source: Synlett - September 28, 2023 Category: Chemistry Authors: Singh, Shweta Gremaud, Ludovic Sen, Subhabrata Maiti, Debajit Tags: cluster Source Type: research
Alternative Synthesis of α-l-Threofuranosyl Guanosine 3′-triphosphate
Synlett DOI: 10.1055/s-0041-1738452 Artificial genetic polymers (XNAs) have attracted considerable attention due to their unique physicochemical properties that include enhanced chemical and biological stability. Unfortunately, some of the most interesting XNAs are constructed from monomers that are not readily available and must be prepared by chemical synthesis. The need to generate building-block materials for these systems warrants careful optimization, as syntheses of XNA monomers can easily exceed ten chemical steps. Here, we evaluate the synthesis of α-l-threofuranosyl guanosine 3′-triphosphate (tGTP), a key subs...
Source: Synlett - September 28, 2023 Category: Chemistry Authors: Sarma, Daisy Majumdar, Biju Chaput, John C. Tags: cluster Source Type: research
Visible-Light-Promoted Synthesis of Vinyloxaziridines from Conjugated Carbonyls
We report the first visible-light-promoted synthesis of vinyloxaziridines from simple conjugated nitrones. We have found that vinyl nitrones formed by the condensation reaction between conjugated carbonyls and hydroxylamines undergo visible-light-promoted energy-transfer isomerization to the respective vinyloxaziridines in very high yields and selectivities. The reaction scope expands to a large array of substitution patterns, and evidence indicates that the proposed energy-transfer pathway is the predominant mechanism for this transformation. [...] Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, GermanyArticle...
Source: Synlett - September 28, 2023 Category: Chemistry Authors: Austin, Brooke E. Palner, Ryan P. Tobias, Elissa M. Madiu, Rufai Doran, Erin L. Doran, Jenna M. Howard, Amari M. Stroud, James L. Rossi, Morgan E. Moskovitz, Dylan A. Rivera, Dominic A. Mullen, Michael D. Zinsky, Amy H. Rosario, Rose A. Moura-Letts, Gusta Tags: cluster Source Type: research
Metal-Free Catalyzed Defluorinative O-Arylation of Pyrazolones with Polyfluoroarenes
Synlett DOI: 10.1055/a-2158-1015 An efficient and general method for defluorinative O-arylation of pyrazolones has been successfully developed under metal-free conditions. This methodology allows for the synthesis of desired products by using a wide range of pyrazolones and polyfluoroarenes as starting materials. The compatibility of various substrates was demonstrated, ensuring the applicability of this method. Furthermore, the synthesis of the target compounds at a gram scale and the ability to perform late-stage modifications highlight the potential of this approach in preparative pharmaceutical synthesis and organofluo...
Source: Synlett - September 27, 2023 Category: Chemistry Authors: Yang, Liu Qin, Tao Liu, Bin Tags: letter Source Type: research
