{"title":"Twofold Alkenylation of Thiophenes with N-Vinylcarbazole via Iron-Catalyzed Regioselective C−H/C−H Coupling","authors":"Takahiro Doba, Rui Shang, Eiichi Nakamura","doi":"10.1002/hlca.202300210","DOIUrl":"10.1002/hlca.202300210","url":null,"abstract":"<p>The incorporation of the vinylene motif into conjugated molecules notably elevates the HOMO level, augmenting both emissive and conductive properties while enhancing responsiveness to external stimuli. This study focuses on the regioselective C−H/C−H coupling of <i>N</i>-vinylcarbazole with thiophenes, offering an efficient route to <i>N</i>-vinylene-incorporated conjugated molecules for the development of organic electronic materials. Traditional palladium-catalyzed Fujiwara-Moritani (FM) reactions proved ineffective for C−H alkenylation with <i>N</i>-vinylcarbazole. In response, we have developed an iron-catalyzed twofold alkenylation method for conjugated thiophenes with <i>N</i>-vinylcarbazole, utilizing trimethylaluminum as the base and diethyl oxalate as the oxidant. This reaction occurs regioselectively at the C<sub>2</sub>−H (or C<sub>5</sub>−H) bond of the thiophenes and the terminal position of <i>N</i>-vinylcarbazole. It also successfully produces short thiophene polymers end-capped with <i>N</i>-vinylcarbazole, demonstrating the potential for synthesizing polymeric donor materials. The enamine products exhibit blue-to-green emission, high fluorescence quantum yield, and visible light responsivity for stereo-isomerization, indicating promising applications in organic electronics.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hlca.202300210","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138632226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Alternative Routes to 4,6-O-Benzylidene β-Thioglycosides","authors":"Daniela Imperio, Filippo Valloni, Luigi Panza","doi":"10.1002/hlca.202300193","DOIUrl":"10.1002/hlca.202300193","url":null,"abstract":"<p>The synthesis of glycosides generally requires the use of building blocks that need to be readily prepared, avoiding tricky reaction steps and boring purifications. Thioglycosides represent key donor intermediates for their activation in glycosylation reactions and for their great stability. Moreover, the presence of a benzylidene moiety confers to the molecule a double advantage: it can influence the stereochemistry of the glycosylation reaction and can be selectively opened to generate different species having a free secondary hydroxyl group. Here, the preparation of <i>p</i>-Tolyl 1-thio-4,6-<i>O</i>-benzylidene-2,3-di-<i>O</i>-benzyl-β-<span>d</span>-pyranoses of glucose, galactose, and mannose are described. The global procedure involved the exploitation of simple reactions and crystallization techniques, having a chromatographic purification for the last step only.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hlca.202300193","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138568406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thirty-Three Years Member of the Group Vasella by Bruno Bernet","authors":"Dr. Bruno Bernet","doi":"10.1002/hlca.202300196","DOIUrl":"10.1002/hlca.202300196","url":null,"abstract":"<p>\u0000 \u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure>\u0000 </p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hlca.202300196","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138546286","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jonathan Long, Pascal Retailleau, Juan Xie, Nicolas Bogliotti
{"title":"Steric Bulk-Dependent Photoresponse of Sulfonamide Azobenzene Ligand in Arene Ruthenium(II) Complexes","authors":"Jonathan Long, Pascal Retailleau, Juan Xie, Nicolas Bogliotti","doi":"10.1002/hlca.202300190","DOIUrl":"10.1002/hlca.202300190","url":null,"abstract":"<p>A series of sulfonamide azobenzenes bearing alkyl substituents of increasing steric bulk at the position <i>ortho</i> to the N=N bond and their corresponding chloro(hexamethylbenzene)ruthenium(II) complexes were synthesized. The latter bearing mono-substituted ligands exhibited an exocyclic azo bond under the <i>E</i> configuration, and underwent reversible <i>E</i>→<i>Z</i> photoisomerization upon irradiation with visible light, followed by thermal <i>Z</i>→<i>E</i> back isomerization upon resting in the dark at 20 °C. In contrast, the corresponding 2,6-dimethyl substituted azobenzene complex, while also exhibiting an exocyclic azo bond, was isolated as the <i>Z-</i>isomer and underwent uncommon solvent dependent irreversible photodissociation of azobenzene ligand upon visible light irradiation. Valuable insights into the photophysical and structural properties of these complexes were gained by combination of computational and X-ray diffraction studies.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hlca.202300190","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138496107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Scott R. Docherty, Philipp Schärz, Domenico Gioffrè, Alexander V. Yakimov, Christophe Copéret
{"title":"Probing the Nature of Surface Hydrides by Deuterium Quadrupolar Parameters: A Case Study on Silica-Supported Zirconium Hydrides","authors":"Scott R. Docherty, Philipp Schärz, Domenico Gioffrè, Alexander V. Yakimov, Christophe Copéret","doi":"10.1002/hlca.202300173","DOIUrl":"10.1002/hlca.202300173","url":null,"abstract":"<p>Supported metal hydrides are key reactive intermediates in various catalytic processes, such as hydrogenation and dehydrogenation, but are often challenging to characterize spectroscopically. Here, deuterium solid state nuclear magnetic resonance spectroscopy is used to understand the structure of the corresponding silica-supported zirconium hydrides after H/D exchange as an illustrative example of supported metal hydrides, which have been shown to display notable reactivity towards small molecules (<i>e. g</i>., CO<sub>2</sub> and N<sub>2</sub>O) and to activate both C−H and C−C bonds, hence their use in to the conversion of hydrocarbons (alkanes, polyolefins <i>etc</i>.)</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hlca.202300173","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138496106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"HFIP Mediated Synthesis of C4-Aryl-2-quinolones through Serial Oxidation","authors":"Seung Hoon Lee, Minseok Kang, Hyung Min Chi","doi":"10.1002/hlca.202300153","DOIUrl":"10.1002/hlca.202300153","url":null,"abstract":"<p>A practical, efficient approach for the synthesis of C4-arylated 2-quinolones from propargylic chlorides and anilines has been developed. The synthesis process involves subsequent oxidations of the initial products, tetrahydroquinolines and quinolinium ions, eventually leading to desired quinolones. A mechanism for the transformation is proposed based on a meticulous examination of intermediates and comprehensive control experiments. With a thorough understanding of the reaction mechanism, the applicability of the reaction scope is expanded.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138496105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Development of Photoredox-Assisted Direct α-Alkylation Reactions of Ketones with Arylalkenes Using a Catalytic Amount of LiOtBu as a Brønsted Base","authors":"Tsubasa Hirata, Tomoya Hisada, Yoshihiro Ogasawara, Shū Kobayashi, Yasuhiro Yamashita","doi":"10.1002/hlca.202300139","DOIUrl":"10.1002/hlca.202300139","url":null,"abstract":"<p>Photoinduced direct α-alkylation reactions of ketones with arylalkenes using an organophotocatalyst and a Brønsted base were developed. It was found that the choice of both Brønsted base and photocatalyst was crucial, and in the presence of catalytic amounts of 2,4,6-tris(diphenylamino)-3,5-difluorobenzonitrile (3DPA2FBN) and LiO<sup><i>t</i></sup>Bu, the desired reactions of ketones with styrene analogues proceeded smoothly under blue-LED light irradiation to afford the products in moderate to high yields. This method constitutes an atom-economical alkylation process for α-functionalization of both cyclic and acyclic ketones.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hlca.202300139","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138496130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cédric Bürki, Stefan Diethelm, Fabio D'Aiuto, Marco Künzli, Gaëlle Mathieu, Christine Schmitt
{"title":"Scalable Preparation of 1-Aminoethyl Oxindoles From Simple Benzaldehydes","authors":"Cédric Bürki, Stefan Diethelm, Fabio D'Aiuto, Marco Künzli, Gaëlle Mathieu, Christine Schmitt","doi":"10.1002/hlca.202300188","DOIUrl":"10.1002/hlca.202300188","url":null,"abstract":"<p>Oxindoles are prevalent structures in natural products and pharmaceutically active molecules. To support structure–activity-relationship (SAR) studies in a medicinal chemistry program, we developed a straightforward and scalable synthesis route to 1-aminoethyl oxindole building blocks harboring various types of substituents. Our strategy relies on an intramolecular Buchwald–Hartwig amidation of a 2-bromophenylacetic amide precursor. The cyclization substrates can be prepared from readily available benzaldehydes by <i>ortho</i>-selective C(sp<sup>2</sup>)−H bromination followed by homologation to the corresponding phenylacetic acid derivatives. The process was optimized to allow for preparation of 246 g of one representative example.</p>","PeriodicalId":12842,"journal":{"name":"Helvetica Chimica Acta","volume":null,"pages":null},"PeriodicalIF":1.8,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138496129","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}