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Piotr Przybylski Marcin Kwit Krystian Pyta Radosław Pankiewicz Grzegorz Schroeder Jacek Gawroński Bogumil Brzezinski 《Tetrahedron: Asymmetry》2010,21(8):973-981
Gossypol Schiff base with (R)-(+)-2-amino-3-benzyloxy-1-propanol 1 was synthesised and resolved by HPLC method into diastereomers to study their atropisomerisation process. The spectroscopic analysis performed by one- and two-dimensional NMR, UV–vis and FT-IR methods indicated that the compound exists in solution as an enamine-oxo tautomer. The ECD measurements and TD-DFT calculations allowed us to unambiguously determine the configuration about the axially chiral biaryl moiety of 1. The conditions of the atropisomerisation processes of diastereopure gossypol Schiff bases (SAX,R)-1 and (RAX,R)-1 were determined on the basis of ECD and NMR measurements. Exposure of the diastereomers of 1 to sunlight and to the light at λ = 254 nm significantly accelerated the atropisomerisation when compared to its rate in the dark. 相似文献
124.
Marcin Dumnicki 《Geometriae Dedicata》2010,147(1):283-311
The Segre-Gimigliano-Harbourne-Hirschowitz Conjecture can be naturally formulated for Hirzebruch surfaces
\mathbbFn{\mathbb{F}_n}. We show that this Conjecture holds for imposed base points of equal multiplicity bounded by 8. 相似文献
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Marcin Jankowiak 《Journal of organometallic chemistry》2005,690(20):4478-4487
Catalytic reactivity of Si-H bond of di-, trisiloxanes with allyl chloride in the presence of platinum catalyst has been examined. Hydrosilylation process competes with hydrogen substitution by chlorine and/or propenyl group. The effect of the reaction conditions as well as structure of siloxane on the yield and selectivity of the number of products has been discussed. Several consecutive-competitive processes have been identified. The results obtained can be helpful in the study of the catalytic hydropolysiloxanes reactions with allyl derivatives-systems of great practical importance, to produce commercial functionalized silicones. 相似文献
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Results of experimental investigations of the effect of drying and atomization parameters on counter-current spray drying
are discussed. Based on 96 experimental tests, the local and global distributions of velocity, temperature, drying air humidity
and moisture content of material dried in the drying tower were determined. Analysis of the results showed that the process
of agglomeration during counter-current spray drying depended mainly on air temperature in the atomization zone. 相似文献
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Marcin Kubisiak Karolina Zelga Wojciech Bury Iwona Justyniak Krzysztof Budny-Godlewski Zbigniew Ochal Janusz Lewiński 《Chemical science》2015,6(5):3102-3108
This paper reports a series of comparative experiments on the activity of carbon- and oxygen-centred radical species in a model reaction of the radical addition of THF to imines mediated by a series of zinc alkyl/air reaction systems. The study strongly contradicts the notion that generally R˙ radicals are the initiating species in organic reactions mediated by RnM/air systems, and simultaneously demonstrates that oxygen-centred radical species are the key intermediates responsible for the initiation process. In addition, a new efficient RZn(L)/air initiating system for radical organic reactions exampled by a model reaction of radical addition of THF to imines is developed. Moreover, the isolation and structural characterization of the first zinc alkylperoxide supported by a carboxylate ligand, [Zn4(μ3-OOtBu)3(μ4-O)(O2CEt)3]2, as well as the novel octanuclear zinc oxo(alkoxide) aggregate with entrapped O–THF species, [Zn4(μ4-O)(μ3-2-O–THF)(O2CEt)5]2, provide clear mechanistic signatures for the mode of function of the RZn(O2CR′)/air system. 相似文献