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2,3-Dioxabicyclo
1Institute of Organic Chemistry University of Wurzburg Am Hubland, D-97074 Wurzburg, Germany; Department of Chemistry, Middle East Technical University, 06531 Ankara; and Department of Chemistry Ataturk University, 25240 Erzurum, Turkey.
The Journal of Organic Chemistry
|September 16, 2000
Summary
Photooxygenation of 1,4-cyclohexadiene yields hydroperoxy endoperoxides and hydroperoxides. Selective reduction and oxidation generate a keto endoperoxide, leading to dihydroxybenzenes and other products via deoxygenation and rearrangement.
Area of Science:
- Organic Chemistry
- Photochemistry
- Reaction Mechanisms
Background:
- 1,4-Cyclohexadiene is a key substrate in organic synthesis.
- Photooxygenation reactions are important for generating oxygenated organic compounds.
- Understanding reaction mechanisms is crucial for synthetic strategy development.
Purpose of the Study:
- To investigate the photooxygenation of 1,4-cyclohexadiene.
- To explore the selective reduction and oxidation of resulting hydroperoxides.
- To elucidate the mechanisms of subsequent transformations including deoxygenation and rearrangement.
Main Methods:
- Photooxygenation of 1,4-cyclohexadiene.
- Selective reduction of hydroperoxide groups using titanium tetraisopropoxide-diethyl sulfide.
- Oxidation using pyridinium chlorochromate (PCC).
- Deoxygenation using triphenylphosphine.
- Cobalt tetraphenylporphyrin (CoTPP)-catalyzed rearrangement.
Main Results:
- Photooxygenation yielded a mixture of diastereomeric hydroperoxy endoperoxides (exo-4, endo-4) and hydroperoxides (trans-5, cis-5).
- Selective reduction produced hydroxy endoperoxides (exo-7, endo-7).
- PCC oxidation afforded the phenol-derived keto endoperoxide (2).
- Triphenylphosphine deoxygenation of keto endoperoxide 2 gave a 9:1 mixture of 1,2- and 1,4-dihydroxybenzenes (10 and 11).
- CoTPP-catalyzed rearrangement produced bisepoxide 12, malealdehyde (13), and beta-lactone 14.
Conclusions:
- The study details a multi-step synthetic pathway starting from 1,4-cyclohexadiene.
- Mechanisms for the photooxygenation, reduction, oxidation, deoxygenation, and rearrangement steps were proposed.
- The findings provide insights into the reactivity of endoperoxides and their synthetic utility.