- Regiochemical Control in the Reductive Cleavage of 2-Alkylated Oxetanes by Use of Trialkylaluminums. Tertiary Organolithiums with γ-Oxy Functionality
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Whereas 2,2-dialkylated oxetanes are cleaved by lithium 4,4'-di-tert-butylbiphenylide to provide the primary organolithium-tertiary oxyanions, the same reaction in the presence of trialkylaluminums gives exclusively the 3-lithio-3,3-disubstituted propoxides, which are trapped by carbonyl compounds in moderate yields.
- Mudryk, Boguslaw,Cohen, Theodore
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p. 5760 - 5761
(2007/10/02)
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- OXYGEN YLIDES-II. PHOTOCHEMICAL AND RHODIUM-CATALYZED REACTIONS OF DIAZOMETHANE WITH (S)-2-METHYLOXETANE
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Photolysis of diazomethane in (S)-2-methyloxetane gives 2- and 3-methyltetrahydrofuran (1:3.2), the latter being formed with 21 percent net retention of configuration.In contrast, rhodium acetate catalysis yields racemic 3-methyltetrahydrofuran exclusively.
- Kirmse, Wolfgang,Chiem, Pham Van
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p. 197 - 200
(2007/10/02)
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- Reactions of Methyl Radicals with 3-Methyloxetane, 3,3-Dimethyloxetane and 2,2-Dimethyloxetane
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The reactions of methyl radicals with 3-methyloxetane, 3,3-dimethyloxetane and 2,2-dimethyloxetane have been studied.The overall rates of hydrogen-atom abstraction from these three compounds have been obtained over the temperature range 100-200 deg C by assuming the value of Quinn and coworkers (J.Chem.Soc.Faraday Trans.I, 1976, 72, 1935) for the rate of recombination of methyl radicals.The following rate expressions were found: log10(k4/cm3mol-1s-1)(30x) = 11.69 (+/-0.20)-38.23 (+/-0.84) kJmol-1/2.303RT, log10(k4/cm3mol-1s-1)(3,30x) = 11.72 (+/-0.20)-39.47 (+/-1.0) kJmol-1/2.303RT, log10(k4/cm3mol-1s-1)(2,20x) = 11.99 (+/-0.23)-41.24 (+/-1.13) kJmol-1/2.303RT.From these rate expressions and those obtained previously for three other oxetane molecules, the rate parameters for hydrogen-atom abstraction from five distinct sites in the substituted oxetane molecules have been obtained.
- Duke, Martin G.,Holbrook, Kenneth A.
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p. 3391 - 3398
(2007/10/02)
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- THERMOLYSES OF 2-METHYLOXETAN AND 2,2-DIMETHYLOXETAN
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The thermolysis of 2-methyloxetan has been reinvestigated at temperatures between 429.5 and 483.2 deg C and initial reactant pressures from 6.0 to 14.2 Torr.Two parallel unimolecular reactions occur producing either propene and formaldehyde or ethene and acetaldehyde.The ratio of propene to ethene is 1.31+/-0.03 within this temperature range.The total rate constant for dissapearance of reactant is given by log10(k/s-1)=(14.89+/-0.36)-(249.8+/-4.7KJ mol-1)/2.303 RT.The thermolysis of 2,2-dimethyloxetan was studied in the same apparatus at temperatures between 402.2 and 471.3 deg C and at reactant pressures from 7.2 to 9.2 Torr.The reactant disappears by two parallel unimolecular paths to give either isobutene and formaldehyde or ethene and acetone.Minor products of methane, propene and isobutane were also detected.The ratio of isobutene to ethene was found to differ considerably from unity and to be strongly temperature-dependent.The following rate expressions were derived for the overall rate of disapperance of reactant (k2,2) and for the rate constants for the individual reactions producing isobutene (k3) and ethene (k4) log10(k2,2/s-1)=(13.78+/-0.24)-(226.0+/-2.7 kJ mol-1)/2.303 RT log10(k3/s-1)=(13.48+/-0.25)-(222.1+/-2.9 kJ mol-1)/2.303 RT log10(k4/s-1)=(15.56+/-0.34)-(270.6+/-4.4 kJ mol-1)/2.303 RT.The differences observed between the thermolyses of these two compounds are noted and compared with previously obtained results for other methyl-substituted oxetans.A possible explanation for the difference in Arrhenius parameters for the two paths in the case of the 2,2-disubstituted compound is suggested.
- Hammonds, Paul,Holbrook, Kenneth A.
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p. 2195 - 2204
(2007/10/02)
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