@article{KruegerLinker2021,
author = {Kr{\"u}ger, Tobias and Linker, Torsten},
title = {Synthesis of gamma-spirolactams by Birch reduction of arenes},
series = {European journal of organic chemistry},
volume = {2021},
journal = {European journal of organic chemistry},
number = {10},
publisher = {Wiley-VCH},
address = {Weinheim},
issn = {1099-0690},
doi = {10.1002/ejoc.202100056},
pages = {1585 -- 1591},
year = {2021},
abstract = {A convenient method for the synthesis of gamma-spirolactams in only three steps is described. Birch reduction of inexpensive and commercially available aromatic carboxylic acids in the presence of chloroacetonitrile affords nitriles in moderate to good yields. Suitable precursors are methyl-substituted benzoic acids, naphthoic, and anthroic acid. Subsequent catalytic hydrogenation proceeds smoothly with PtO2 or Raney Ni as catalysts and lactams are isolated in excellent yields and stereoselectivities. Thus, up to 3 new stereogenic centers can be constructed as sole diastereomers from achiral benzoic acids. Furthermore, it is possible to control the degree of saturation at different pressures, affording products with 0, 1, or 2 double bonds. Overall, more than 15 new gamma-spirolactams have been synthesized in analytically pure form.},
language = {en}
}
@article{FudickarMetzMaiLindeetal.2021,
author = {Fudickar, Werner and Metz, Melanie and Mai-Linde, Yasemin and Kr{\"u}ger, Tobias and Kelling, Alexandra and Sperlich, Eric and Linker, Torsten},
title = {Influence of functional groups on the ene reaction of singlet oxygen with 1,4-cyclohexadienes},
series = {Photochemistry and photobiology : the official journal of the American Society for Photobiology},
volume = {97},
journal = {Photochemistry and photobiology : the official journal of the American Society for Photobiology},
number = {6},
publisher = {Wiley},
address = {Malden, Mass.},
issn = {0031-8655},
doi = {10.1111/php.13422},
pages = {1289 -- 1297},
year = {2021},
abstract = {The photooxygenation of 1,4-cyclohexadienes has been studied with a special focus on regio- and stereoselectivities. In all examples, only the methyl-substituted double bond undergoes an ene reaction with singlet oxygen, to afford hydroperoxides in moderate to good yields. We explain the high regioselectivities by a "large-group effect" of the adjacent quaternary stereocenter. Nitriles decrease the reactivity of singlet oxygen, presumably by quenching, but can stabilize proposed per-epoxide intermediates by polar interactions resulting in different stereoselectivities. Spiro lactams and lactones show an interesting effect on regio- and stereoselectivities of the ene reactions. Thus, singlet oxygen attacks the double bond preferentially anti to the carbonyl group, affording only one regioisomeric hydroperoxide. If the reaction occurs from the opposite face, the other regioisomer is exclusively formed by severe electrostatic repulsion in a perepoxide intermediate. We explain this unusual behavior by the fixed geometry of spiro compounds and call it a "spiro effect" in singlet oxygen ene reactions.},
language = {en}
}
@article{Schwarze2021,
author = {Schwarze, Thomas},
title = {Determination of Pd2+ by fluorescence enhancement caused by an off-switching of an energy- and an electron transfer},
series = {ChemistrySelect},
volume = {6},
journal = {ChemistrySelect},
number = {3},
publisher = {Wiley-VCH},
address = {Weinheim},
issn = {2365-6549},
doi = {10.1002/slct.202003975},
pages = {318 -- 322},
year = {2021},
abstract = {In this paper, we introduce a fluorescent dye 1, which is able to detect selectively Pd2+ by a clear fluorescence enhancement (FE) in THF. In the presence of eight Pd2+ equivalents, we observed a fluorescence enhancement factor (FEF) of 28.3. The high Pd2+ induced FEF can be explained by an off switching of multiple quenching processes within 1 by Pd2+. In the free dye 1 a photoinduced electron transfer (PET) and energy transfer (ET) takes place and quenches the anthracenic fluorescence. The coordination of eight Pd2+ units by the alkylthio-substituted porphyrazine receptor suppresses the PET and ET quenching process and the anthracenic fluorescence is switched on.},
language = {en}
}
@article{SandSchmidt2021,
author = {Sand, Patrick and Schmidt, Bernd},
title = {Pd-catalyzed oxidative sulfoalkenylation of acetanilides and traceless removal of the catalyst directing group},
series = {ChemistrySelect},
volume = {6},
journal = {ChemistrySelect},
number = {14},
publisher = {Wiley-VCH},
address = {Weinheim},
issn = {2365-6549},
doi = {10.1002/slct.202101009},
pages = {3563 -- 3567},
year = {2021},
abstract = {The palladium-catalyzed oxidative Heck-reaction, also referred to as Fujiwara-Moritani-reaction, has been investigated for the synthesis of styrenylsulfonyl compounds. Acetanilides and vinylsulfonyl compounds undergo dehydrogenative coupling reactions in moderate to quantitative yields, using benzoquinone as the oxidant of choice. Potassium peroxodisulfate, which had previously been identified as a superior oxidant for the coupling with acrylates, did not provide any coupling products with these olefins. Traceless removal of the catalyst directing group through a deacetylation-diazotation-coupling (DDC) sequence was demonstrated for 2-arylethene sulfones.},
language = {en}
}
@article{RajuKoetz2021,
author = {Raju, Rajarshi Roy and Koetz, Joachim},
title = {Inner rotation of Pickering Janus emulsions},
series = {Nanomaterials : open access journal},
volume = {11},
journal = {Nanomaterials : open access journal},
number = {12},
publisher = {MDPI},
address = {Basel},
issn = {2079-4991},
doi = {10.3390/nano11123312},
pages = {6},
year = {2021},
abstract = {Janus droplets were prepared by vortex mixing of three non-mixable liquids, i.e., olive oil, silicone oil and water, in the presence of gold nanoparticles (AuNPs) in the aqueous phase and magnetite nanoparticles (MNPs) in the olive oil. The resulting Pickering emulsions were stabilized by a red-colored AuNP layer at the olive oil/water interface and MNPs at the oil/oil interface. The core-shell droplets can be stimulated by an external magnetic field. Surprisingly, an inner rotation of the silicon droplet is observed when MNPs are fixed at the inner silicon droplet interface. This is the first example of a controlled movement of the inner parts of complex double emulsions by magnetic manipulation via interfacially confined magnetic nanoparticles.},
language = {en}
}
@article{HermannsKeller2021,
author = {Hermanns, Jolanda and Keller, David},
title = {School-related content knowledge in organic chemistry},
series = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society},
volume = {98},
journal = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society},
number = {3},
publisher = {American Chemical Society},
address = {Washington},
issn = {0021-9584},
doi = {10.1021/acs.jchemed.0c01415},
pages = {763 -- 773},
year = {2021},
abstract = {In this paper the development, use, and evaluation of tasks based on the construct of school-related content knowledge are described. The tasks were used in seminars on organic chemistry for bachelor and master preservice chemistry teachers at a German university. For the evaluation a questionnaire with open and closed items was used. The tasks were rated by the preservice chemistry teachers as relevant for their future profession as a chemistry teacher if the content of the tasks is part of the school curriculum. If the content does not belong to the school curriculum, they rated the nature of the tasks still as relevant; they seem to recognize the importance of conceptual knowledge for their future profession. However, the master's preservice teachers argued with this conceptual knowledge more often than the bachelor's preservice teachers. Although the study is cross-sectional, a certain shift from the focus on the content to conceptual knowledge from bachelor's to master's preservice teachers can be observed.},
language = {en}
}
@article{Picconi2021,
author = {Picconi, David},
title = {Nonadiabatic quantum dynamics of the coherent excited state intramolecular proton transfer of 10-hydroxybenzo[h]quinoline},
series = {Photochemical \& photobiological sciences},
volume = {20},
journal = {Photochemical \& photobiological sciences},
number = {11},
publisher = {Springer},
address = {Heidelberg},
issn = {1474-905X},
doi = {10.1007/s43630-021-00112-z},
pages = {1455 -- 1473},
year = {2021},
abstract = {The photoinduced nonadiabatic dynamics of the enol-keto isomerization of 10-hydroxybenzo[h]quinoline (HBQ) are studied computationally using high-dimensional quantum dynamics. The simulations are based on a diabatic vibronic coupling Hamiltonian, which includes the two lowest pi pi* excited states and a n pi* state, which has high energy in the Franck-Condon zone, but significantly stabilizes upon excited state intramolecular proton transfer. A procedure, applicable to large classes of excited state proton transfer reactions, is presented to parametrize this model using potential energies, forces and force constants, which, in this case, are obtained by time-dependent density functional theory. The wave packet calculations predict a time scale of 10-15 fs for the photoreaction, and reproduce the time constants and the coherent oscillations observed in time- resolved spectroscopic studies performed on HBQ. In contrast to the interpretation given to the most recent experiments, it is found that the reaction initiated by 1 pi pi* <- S-0 photoexcitation proceeds essentially on a single potential energy surface, and the observed coherences bear signatures of Duschinsky mode-mixing along the reaction path. The dynamics after the 2 pi pi* <- S-0 excitation are instead nonadiabatic, and the n pi* state plays a major role in the relaxation process. The simulations suggest a mainly active role of the proton in the isomerization, rather than a passive migration assisted by the vibrations of the benzoquinoline backbone.
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language = {en}
}
@article{HermannsKeller2021,
author = {Hermanns, Jolanda and Keller, David},
title = {How do preservice chemistry teachers rate tasks following the construct of school-related content knowledge in a concept-orientated course on organic chemistry?},
series = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society},
volume = {98},
journal = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society},
number = {11},
publisher = {American Chemical Society},
address = {Washington},
issn = {0021-9584},
doi = {10.1021/acs.jchemed.1c00593},
pages = {3442 -- 3449},
year = {2021},
abstract = {In this paper, we describe a study on tasks following the construct of school-related content knowledge. We know from previous studies that such tasks were rated by the preservice chemistry teachers as important for their future profession. Those studies were conducted in a traditional course on organic chemistry which was organized around chemical families. Therefore, we used and evaluated the tasks again in a new course on organic chemistry which is organized around basic concepts in organic chemistry. The results of this evaluation show that the students rate the tasks equally well but use other arguments for their rating. They do not focus only on the content of the tasks and whether this content belongs to the school curriculum or not. The students of the conceptual course rated the content more often (95\%) as important for their future profession compared with the students in the traditional course (57\%). Both groups of students rated the importance of the nature of the task the same way.},
language = {en}
}
@article{Hermanns2021,
author = {Hermanns, Jolanda},
title = {The task navigator following the STRAKNAP concept},
series = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society},
volume = {98},
journal = {Journal of chemical education / Division of Chemical Education, Inc., American Chemical Society},
number = {4},
publisher = {American Chemical Society},
address = {Washington},
issn = {0021-9584},
doi = {10.1021/acs.jchemed.0c01162},
pages = {1077 -- 1087},
year = {2021},
abstract = {Educational Scaffolding was first mentioned in 1976 by Wood et al. Several examples for scaffolding in chemistry are also known from the literature. As written scaffolds, stepped supporting tools to support students while solving problems in organic chemistry were developed, applied, and evaluated. Although the students rated the tool as very helpful, a think-aloud study showed that the support given by this scaffold was not sufficient. As a further development of stepped supporting tools, task navigators were therefore developed, applied, and evaluated. This new scaffold gives tips on strategy, knowledge, and application of knowledge after the STRAKNAP concept. The evaluation of this tool shows that the students rated the tool as being very helpful. A think-aloud study showed that the scaffold supports the students while they solve a problem. Because of the stepwise construction of the task navigators and the providing of the knowledge needed for the application, the students can solve parts of the task successfully even if they do not solve all parts correctly; the students can always start from scratch. When students use the tool regularly, their knowledge of organic chemistry increases compared to students who did not use the tool at all. The task navigator is not only a scaffold for the content of the task but also for the development of methodological competences on the field of strategies and applying knowledge.},
language = {en}
}
@article{KruegerBramborgKellingetal.2021,
author = {Kr{\"u}ger, Tobias and Bramborg, Andrea and Kelling, Alexandra and Sperlich, Eric and Linker, Torsten},
title = {Birch Reduction of Arenes as an Easy Entry to γ-Spirolactones},
series = {European journal of organic chemistry},
volume = {2021},
journal = {European journal of organic chemistry},
number = {46},
publisher = {Wiley-VCH},
address = {Weinheim},
issn = {1434-193X},
doi = {10.1002/ejoc.202101018},
pages = {6383 -- 6391},
year = {2021},
abstract = {A convenient method for the synthesis of γ-spirolactones in only 2-3 steps is described. Birch reduction of inexpensive and commercially available aromatic carboxylic acids in the presence of ethylene oxide affords hydroxy acids, which undergo direct lactonization during work-up. Suitable precursors are methyl-substituted benzoic acids, naphthoic, and dicarboxylic acids. Subsequent hydrogenation proceeds smoothly with Pd/C as catalyst and saturated γ-spirolactones are isolated in excellent yields and stereoselectivities. Thus, up to 3 new stereogenic centers can be constructed as sole diastereomers from achiral benzoic acids. Furthermore, it is possible to control the degree of saturation with Raney nickel or Wilkinson's catalyst to obtain products with 1 double bond. Overall, more than 30 new γ-spirolactones have been synthesized in analytically pure form.},
language = {en}
}