- A Change from Kinetic to Thermodynamic Control Enables trans-Selective Stereochemical Editing of Vicinal Diols
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Here, we report the selective, catalytic isomerization of cis-1,2-diols to trans-diequatorial-1,2-diols. The method employs triphenylsilanethiol (Ph3SiSH) as a catalyst and proceeds under mild conditions in the presence of a photoredox catalyst and under
- Gu, Xin,Wendlandt, Alison E.,Zhang, Yu-An
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supporting information
p. 599 - 605
(2022/01/03)
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- Molecules with Twist Bent Bonds. The Synthesis, Properties, and Reactions of trans-Bicyclohept-3-ene and Certain Methylated Derivatives
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trans-Bicyclohept-3-ene, 7-methyl-trans-bicyclohept-3-ene, and 7,7-dimethyl-trans-bicyclohept-3-ene have been synthesized.Comparison of their ease of oxidation with the ease of oxidation of the analogous cis-bicyclohept-3-enes has been made.Both the thermal and transition-metal complex promoted rearrangements of the trans-bicyclohept-3-enes have been studied.These systems thermally convert to the cis-bicyclohept-3-enes above 100 deg C and are catalytically rearranged at ambient temperature.Trans to cis isomerization alsooccurs at ambient temperature under photoinduced single electron transfer conditions.
- Gassman, Paul G.,Bonser, Steven M.,Mlinaric-Majerski, Kata
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p. 2652 - 2662
(2007/10/02)
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- Trapping of the 6,6-Dimethylbicyclohept-2-yl Free Radical by SH2 Reaction upon Peracid
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The free radical 6,6-dimethylbicyclohept-2-yl (7) has been obtained by decarboxylation of cis- or trans-6,6-dimethylbicycloheptane-2-peroxycarboxylic acids (6a and 6b). 7 trapped by reaction with the initial peracid gave a stereochemical mixture of α- and β-nopinol (8a and 8b).The ratio 8b/8a is around 12, independent of the initial peracid 6a or 6b and its initial concentrations.This value is mainly due to the steric effect of one of the methyl groups branched on C7 in 7.The structure of 7 is discussed.By a competitive reaction 7 undergoes ring opening to afford 2-(3-cyclohexenyl)-2-propyl free radical (9) which by reaction upon peracid leads to 2-(3-cyclohexenyl)-2-propanol (10). 7 was successfully trapped because its reaction with peracid is rapid enough.The ratio of the two alcohols 8/10 leads to an estimation of 1*106 M-1 s-1 for the rate constant of the reaction of 7 with peracids
- Fossey, Jacques,Lefort, Daniel,Sorba, Janine
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p. 3584 - 3587
(2007/10/02)
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- Deamination Reactions, 40. Decomposition of 3,3-, 5,5-, and 7,7-Dimethyl-2-norbornanediazonium Ions
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gem.-Dimethylnorbornyl cations (3, 5) were generated by decomposition of optically active diazonium ion precursors. 6,1- and 6,2-H shifts were detected by structural isomerization and racemization, respectively.Product distributions and optical activities were profoundly affected by the polarity of the solvent.In weakly polar solvents, substitution reactions were associated with much less racemization than hydrogen shifts.Our observations are incompatible with equilibrating open ions but are reasonably explained in terms of unsymmetrical ion pairs.
- Kirmse, Wolfgang,Brandt, Sigrid
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p. 2510 - 2523
(2007/10/02)
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