Epoxidation of trans-cyclooctene by Methyltrioxorhenium/H(2)O(2): reaction of trans-epoxide with the monoperoxo complex
The epoxidation of trans-cyclooctene (trans-1) with the MTO/H(2)O(2), MTO/UHP, and NaY/MTO/H(2)O(2) oxidants leads to a mixture of trans/cis-olefins 1, trans/cis-epoxides 2, and the cis-diol 3. While the oxygen transfer proceeds stereoselectively, the monoperoxo rhenium complex A, which is generated in situ during the catalytic cycle, is responsible for the facile deoxygenation, isomerization, and hydrolysis of the trans-epoxide. In the case of the homogeneous MTO/H(2)O(2) system, rapid decomposition of the catalytically active rhenium species into HReO(4) circumvents the formation of such side products. In contrast, for the heterogeneous oxidants MTO/UHP and NaY/MTO/H(2)O(2), the catalytically active rhenium species are sufficiently stabilized and survive long enough to promote the observed side reactions.
Adam
W
Institut fur Organische Chemie der Universitat Wurzburg, Am Hubland, D-97074 Wurzburg, Germany.
Saha-Moller
CR
Weichold
O