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•Brønsted acid-induced one-pot synthesis of 2-methylbenzofurans.•Construction of new C–O bond formation via an efficient Grob-type fragmentation.•Halobenzofurans were successfully ...utilized to synthesis 6,7-bisaryl benzofurans.
An efficient Brønsted acid-induced one-pot syntheses of 2-methylbenzofurans from norbornyl derivatives have been reported. The construction of new C–O bond proceeds via Grob-type fragmentation followed by cyclization and aromatization respectively. This synthetic strategy facilitates the efficient synthesis of 2-methylbenzofurans under acidic conditions. Significantly, this methodology is successfully applied to the synthesis of 6,7-bisaryl benzofurans.
A unique differential reactivity between dihydroisoquinolines and 3-nitrocoumarins was observed and was exploited for the efficient construction of lamellarins and their isomeric ...benzofuran-8-oxoprotoberberine derivatives under acid-catalyzed or base-promoted conditions. Further, these prepared aryl-substituted benzofuran-8-oxoprotoberberine derivatives bearing electron-donating substituents on benzofuran moiety are found to be benchtop stable but light-sensitive, and can undergo oxidative ring-opening reaction to give the corresponding keto products when exposed to visible light under aerobic conditions.
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•Trifluoromethylated ferrocene analogues of crispines and lamellarins.•Grob reaction between CF3-containing conjugated nitroolefins and ferrocenocpirydines.•Simple one-pot method for ...the synthesis of novel ferrocene-fused indolizines.
Ferrocene analogues of pyrrolo2,1-aisoquinoline alkaloids, 2-(trifluoromethyl)-5,6-dihydroferrocenogindolizine and 6-(trifluoromethyl)-8,9-dihydro-6H-chromeno4,3-bferrocenogindolizines, were obtained in 44–65% yield via the Grob reaction between 1-nitro-1-(2,2,2-trifluoroethylidene)alkanes or 3-nitro-2-(trifluoromethyl)-2H-chromenes and 1-alkyl-3,4-dihydroferrocenocpyridines in 2-propanol at reflux.
Poleti leta 1998 so pri urejanju parkirišča na Jelenovem klancu v Kranju izvedli zaščitna izkopavanja. V naravni niši pod konglomeratno steno so naleteli na depo, ki ga sestavlja več kot 400 ...bronastih predmetov – orožje, orodje, nakit, pločevina in ingoti ter železova žlindra in železova ruda. Predmeti v depoju so iz obdobja med 10. in 8. st. pr. n. št., ko so bili verjetno tudi odloženi. Kemična sestava predmetov, predvsem uhatih sekir, v leguri izkazuje razmeroma velike deleže svinca in v nekaj primerih tudi železa. V bližini depoja so v naselbinskih plasteh odkrili številne sočasne keramične najdbe in bronasti igli, nedaleč stran pa je bil tudi sočasen skeletni grob novorojenčka.
A general approach toward the synthesis of multi-functionalized diazapentacene derivatives 1, using 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene (TDCp, 2), a substituted benzene-1,2-diamine (ADA, ...6), and a naphthalene-1,4-dione (BQ, 3) as the building units, is described. The synthesis basically entails three operations: (i) oxidation of the dichloroetheno-bridge in the Diels-Alder cycloadduct 4 of TDCp and 3, (ii) condensation of the 1,2-diketone 5 thus generated with an ADA to give quinoxaline-fused polycyclic compounds 7, followed by (iii) an one-pot, three-reaction process keyed upon the base- or acid-catalyzed aromatization-driven Grob-type fragmentation to produce quinoxaline ring-embedded diazapentaceneesters 1. The diazapentacene derivative 1a underwent the nucleophilic aromatic ipso-amination with primary and secondary amines to afford the amino-substituted derivatives 12, which tend to self-assemble in solid state driven by the cofacial π-stacking interactions, demonstrated by the crystal packing structures of 12a and 12f.
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•The multi-functionalized diazapentacene derivatives 1 can be synthesized by a general and flexible approach, using 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene, a substituted benzene-1,2-diamine, and a naphthalene-1,4-dione as the building units.•The diazapentacene derivatives 1 have an electronic structure exhibiting high electron affinity and are good candidates for n-type semiconducting material.•The diazapentacene derivatives 1 undergo the ipso-amination with electron-donating primary and secondary amines as nucleophiles, paving the way for exploring prospective application of synthesizing the D–π–A molecules (push–pull systems).
•Novel pentiptycene-based stationary phases.•High-resolution separation of the Grob mixture and xylene isomers.•High column inertness towards organic acids.•Advantageous performance over the ...commercial columns.•Good potential for practical analysis of complex samples.
This work presents the investigation of two new pentiptycene (PP)-functionalized triblock copolymers (PEPE1, PEPE2) for gas chromatographic (GC) analyses with an aim to address the separation problems toward analytes of high resemblance in properties and a wide variety of components in complex samples. Up to date, these two materials are not reported in any fields. The PEPE1 and PEPE2 columns showed close column efficiency (above 4000 plates/m) but differed in polarity, morphology and separation performance. As testified by the challenging Grob test mixture, the PEPE1 column exhibited comprehensively higher separation capability than the PEPE2 column and the commercial reference columns. Also, the PEPE1 column achieved high-resolution performance for both apolar and polar isomers of high resemblance, such as xylenes, phenols and anilines. Moreover, it displayed high inertness towards carboxylic acids and excellent separation repeatability and reproducibility tested by the aniline isomers with the RSD values in the range of 0.01–0.04% for run-to-run, 0.09–0.13% for day-to-day and 1.2–2.0% for column-to-column, respectively. Its application to GC–MS analysis of the essential oil from tea flowers demonstrated its advantageous separation performance towards a wide range of components and proved its feasibility for practical analyses of complex samples.
Trabalhar com sucata Maximiano Costa, Ian Anderson
REVELL : Revista de Estudos Literários da UEMS,
04/2023, Letnik:
1, Številka:
34
Journal Article
Recenzirano
Odprti dostop
Nascido na cidade de Dniepropietrovsk, na Ucrânia, Vadim Sidúr (1924-1986) se formou na escola de artes de Moscou sob o regime soviético. Nesse espaço oficialista dominado pela estética do realismo ...socialista o escultor optou por trabalhar com os restos, os materiais inservíveis: alumínio, ferro e metais retorcidos e enferrujados. Em suma, o lixo. A partir disso, neste ensaio lemos a obra do soviético por meio da noção de gambiarra: através das sucatas da industrialização Sidúr produz objetos estéticos mal ajambrados, elementos que perderam seu valor de uso e também de troca são transformados (montados) em “parafernálias” carregadas de política.
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•Novel unconventional nitrooxylation of the heterocyclic methyl group.•Simple synthesis of 3-nitrooxyalkyl furoxans.•Mild reaction conditions and simple procedure.•New Grob-type ...fragmentation was proposed for the conversion of 3-methylfuroxans to 3-nitrooxyalkyl furoxans.
A short and efficient synthesis of 1-(2-oxido-1,2,5-oxadiazol-3-yl)alkyl nitrates from 3-alkyl-1,2,5-oxadiazole 2-oxides, using a mixture of nitric and sulfuric acids in chloroform, has been developed. The scope of the unconventional reaction was established; its mechanism likely included a new Grob-type fragmentation.
V času kulture žarnih grobišč, zlasti v prehodnem obdobju v starejšo železno dobo se je na Gorenjskem izoblikovala posebna kulturna skupina, ki jo označuje vrsta njej lastnih značilnosti: 1 – ...naselbine v več nivojih z jedrom na vzpetini oz. naravno zavarovanem kraju in spodnjim naseljem v dolini/ kotlini (Kranj, Bled, Mengeš, Ljubljana), za katere menimo, da prestavljajo središča lokalnega značaja; 2 – žgan pokop tako v planih grobovih/grobiščih kot tudi v gomilah, pogosto s centralnimi grobnimi kamrami; 3 – grobovi so pretežno opremljeni s skromnimi pridatki, izjeme predstavljajo le nekateri grobovi z večjim številom keramičnih posod, ki tvorijo jedilno-pivske servise in nekateri bogatejši ženski grobovi, ki izstopajo po svojem nakitu. Moški grobovi so povečini skromno opremljeni, v starejšem halštatskem obdobju v njih praviloma ni orožja. Do sprememb v prilaganju orožja v grobove je prišlo v mlajšem obdobju, kar pa ni značilno le za Gorenjsko, temveč je veliko širši fenomen. Kljub očitnim podobnostim in stikom Gorenjske s sosednjimi kulturnimi skupinami, kot so skupina Breg/Frög na Koroškem in štajersko-panonska skupina, estenska in svetolucijska skupina ter dolenjska skupina, so razlike med njimi tako evidentne, da v samosvojost gorenjske ali gorenjsko-ljubljanske kulturne skupine v halštatskem obdobju ni za dvomiti.
Introduction Tomes, Nancy; Jones, Kathleen W
Journal of the history of medicine and allied sciences,
01/2019, Letnik:
74, Številka:
1
Journal Article
Recenzirano
This article offers an overview of the life and work of Gerald N. Grob. As part of a generation of scholars intent on overturning the old "Whig history" of medicine, Grob pioneered the use of ...institutional history as an analytical tool. His work on American psychiatry combined a formidable command of archival sources with a strong commitment to putting medical practice in social context. Grob's personal and political views put him at odds with other scholars of the asylum; he conducted some very public feuds with David Rothman and Andrew Scull. At the same time, he showed a more benevolent side to younger historians interested in psychiatry; he took particular pains to encourage women (including the authors of this introduction) to enter a historical specialty then dominated by men. To honor Grob's legacy as a scholar and a person, this special issue features articles written by several generations of scholars influenced and inspired by his work.
