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121.
[formula: see text] The reaction of secondary and primary alcohols with highly fluorinated 3,4,5-tris(5,5,6,6,7,7,8,8,9,9,10,10,11,11,12,12,12-heptadecafluorododecan- 1-yloxy)benzoic acid in the presence of Ph3P and DIAD in THF at room temperature (fluorous Mitsunobu) resulted in a simple, chromatography-free isolation protocol with excellent yields (83-96%). 相似文献
122.
Addition of dipropylamine to multiacrylate and its model compound catalyzed by lithium dipropylamide
The nucleophilic addition reaction of dipropylamine to vinyl groups of multiacrylate - poly(2-acryloyloxyethyl methacrylate)
and to 2-butyrylethyl acrylate as model compound has been investigated. Based on the results obtained, it has been shown that
the addition reaction rate of dipropylamine to multiacrylate and 2-butyrylethyl acrylate is proportional to [CH2=CH-] and to [(C3H7)2NLi] with the ratio [(C3H7)2NH]o/[(C3H7)2NLi]o = 20. Second-order addition reaction rate constants and activation energies for the systems under investigation have been
determined.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
123.
124.
Roman Bashkurov Dr. Alexander Kaushansky Dr. Boris Tumanskii Dr. Natalia Fridman Dr. Dmitry Bravo-Zhivotovskii Prof. Dr. Yitzhak Apeloig 《Angewandte Chemie (International ed. in English)》2023,62(18):e202300847
Thermolysis of a 1 : 1 mixture of tris(di-tert-butylmethylsilyl)germane 9 and bis(di-tert-butylmethylsilyl)germane 17 at 100 °C produces unexpectedly octagermacubane 18 , having two 3-coordinate Ge0 atoms (40 % yield). 18 was characterized by X-ray crystallography and it is a singlet biradical (according to DFT quantum mechanical calculations and the absence of an EPR signal). Reactions of 18 with CH2Cl2 and H2O yield the novel dichloro-octagermacubane 24 and hydroxy-octagermacubane 25 , respectively. Reduction of 18 with tBuMe2SiNa in THF produces an isolable octagermacubane radical anion 26-Na . Based on X-ray crystallography, EPR spectroscopy and DFT quantum mechanical calculations, 26-Na is classified as a Ge-centered radical anion. 相似文献
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127.
Rudolf Knorr Ernst Lattke Jakob Ruhdorfer Kathrin Ferchland Ulrich von Roman 《Tetrahedron》2018,74(14):1621-1631
Common wisdom might anticipate that two methyl groups placed on a molecular migration route should act as an impediment. However, the “conducted tour” migration of Li+(THF)4 across the aryl ring (“π-route”) during the cis/trans stereoinversion of α-arylvinyllithiums had been found to occur with practically equal velocities in the presence of either one or two ortho-alkyl substituents. We now report that the omission of both ortho-methyl groups retards the stereoinversion process. In order to arrive at an answer to the title question, we investigate the aggregation equilibria and microsolvation states of ortho, ortho′-unsubstituted α-lithiostyrenes by means of approved secondary NMR criteria. Beyond such necessary knowledge about the ground-state properties, we provide kinetic evidence showing that the retarded cis/trans stereoinversion of α-lithiostyrene proceeds by the pseudomonomolecular, ionic mechanism with Li+(THF)4 migration. 相似文献
128.
Transition Metal Free Cycloamination of Prenyl Carbamates and Ureas Promoted by Aryldiazonium Salts 下载免费PDF全文
Roman Abrams Dr. Quentin Lefebvre Prof. Jonathan Clayden 《Angewandte Chemie (International ed. in English)》2018,57(41):13587-13591
Upon treatment with aryldiazonium salts, prenyl carbamates and ureas undergo redox‐neutral azocycloamination. In general, N‐aryl O‐prenyl carbamates cyclize in a photocatalytic reaction with visible light and an organic dye. With electron‐deficient diazonium salts, electronic matching with an electron‐rich N‐aryl substituent results in a reaction proceeding in the ground state, without either light or photocatalyst. Cyclic voltammetry suggests that this radical reaction is initiated by hydrogen‐atom abstraction mediated by an aryl radical, followed by a radical addition cascade and proton‐coupled hole propagation. The reaction proceeds at room temperature in short reaction times, and a range of functional groups is tolerated. 相似文献
129.
Roman Luboradzki Janusz Lipowski Yurii A. Simonov Marina S. Fonari Edward V. Ganin Arkadii A. Yavolovskii 《Journal of inclusion phenomena and macrocyclic chemistry》2001,40(1-2):59-65
The X-ray crystal structures of two closely related molecular complexes of 15-crown-5 and benzo-15-crown-5 with 3,4-diamino-1,2,5-oxadiazole are reported (I and II). Both complexes are of 1:1 stoichiometry with the host–guest alternation in the infinitechains formed due to the unsymmetrical H-bonding patterns between the components. Crystals of I are monoclinic, P21/c, a = 7.856(3), b = 12.994(1), c = 16.033(1) , = 94.79(2)°, Z = 4, final R-factor is 0.0488. Crystals of II are orthorhombic, P212121, a = 8.260(4), b = 15.692(5),c = 13.955(7) , Z = 4, final R-factor is 0.0522. 相似文献