- Ozonolyses of α-Oxo-alkenes: On the Existence of α-Oxo-ozonides
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Ozonolyses of nine acyclic (1a-i) and two cyclic (14, 29) α-oxo-alkenes on polyethylene or in pentane afforded in eight cases (1d-i, 14, 29) isolable α-oxo-ozonides. α-Diozonides (9) are obtained from five of the acyclic α-oxo-alkenes (1a, b, d, g, h).All isolated ozonides are labile; the 2,4-dinitrophenylhydrazones of the α-oxo-ozonides, however, are very stable.Decomposition of the α-oxo-ozonides affords not only the hitherto known fragments, but non-peroxidic isomers (8) of the ozonides, too.
- Griesbaum, Karl,Greunig, Hans-Joachim,Volpp, Willi,Jung, In-Chan
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p. 947 - 956
(2007/10/02)
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- Diozonolyses of Acyclic Conjugated Dienes in Methanol
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In the diozonolyses of isoprene (1a), 2-methyl-3-phenyl-1,3-butadiene (1b), 2,3-diphenyl-1,3-butadiene (26), and 2,3,4,5-tetramethyl-2,4-hexadiene (30) in methanol subsequent reactions of the primary cleavage products afforded abnormal products, which arose from cleavage of both the double bonds and the single bonds of the diene systems.In addition, the diozonolyses of 26 and 30 gave products, in which one of the double bonds of the respective diene system has been epoxidized.The mode of formation of the abnormal cleavage products has been elucidated by the ozonolysis of the intermediate products, viz. of α,β-unsaturated methoxyhydroperoxides and of α,β-unsaturated carbonyl compounds.
- Griesbaum, Karl,Zwick, Gerhard
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p. 229 - 243
(2007/10/02)
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- Monoozonolyses of Acyclic Conjugated Dienes
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Monoozonolyses of isoprene (1a), 2-methyl-3-phenyl-1,3-butadiene (1b), 2,3-diphenyl-1,3-butadiene (25), and 2,3,4,5-tetramethyl-2,4-hexadiene (34) have been examined in pentane and in methanol.The dienes 1a, b and 25 afforded all possible α,β-unsaturated monoozonides and α,β-unsaturated methoxy hydroperoxides, respectively, whereas diene 34 gave no ozonide and no α,β-unsaturated methoxy hydroperoxide.From the dienens 25 and 34, the corresponding monoepoxides have been formed additionally.The results allow some conclusions concerning the regioselectivity of ozone attack at the unsymmetrically substituted dienes 1a, b as well as concerning the cleavage directions of primary ozonides.
- Griesbaum, Karl,Zwick, Gerhard
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p. 3041 - 3057
(2007/10/02)
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- Ozonolysis of Some Tetrasubstituted Ethylenes
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The olefins 1,4-dibromo-2,3-dimethyl-2-butene, 1-bromo-2,3-dimethyl-2-butene, and 2,3-dimethyl-2-butene were ozonized under a variety of conditions.Ozonolysis of 1,4-dibromo-2,3-dimethyl-2-butene in acetone solvent leads to the unexpected products acetone diperoxide and triperoxide.The results are discussed with respect to questions of concertedness in ozonide formation, the need for activating groups in ozonide formation, and the possible intermediacy of dioxiranes.
- Murray, Robert W.,Agarwal, Sudhir K.
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p. 4698 - 4702
(2007/10/02)
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