Singlet oxygenation of cycloocta-1,3,5-triene: Formation of (4.2.2)- and (2.2.2)- cycloadducts.

✍ Scribed by Waldemar Adam; Ihsan Erden

• Publisher: Elsevier Science
• Year: 1979
• Tongue: French
• Weight: 216 KB
• Volume: 20
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)86415-7

✦ Synopsis

Photosensitized singlet oxygenation of 1,3,5-cyclooctatriene affords the (4.2.2)-and (2.2.2)-type endoperoxides, which were reduced with diimide, thermally isomerized, and deoxygenated with triphenylphosphine.

Cycloocta-1,3,5-triene (k) is a versatile substrate for cycloaddition in view of its diverse dienic reactivity.

3 Thus, in principle the (2+4) -cycloadducts ;2: and 2.2. can be obtained, representing respectively the (i-2.2)-and (2.2.2)products of the monocyclic (;tla) and bicyclic (t_b) valence isomers (eq. 1). For example, with N-phenyl-1,2,4-triazoline-3,5-dione we confirmed that the respective urazole derivatives zc and 2.Q were formed in 80% and 20% yields.5

Since singlet oxygen resembles g-phenyl-1,2,4-triazoline-3,5-dione in its dienophilic reactivity, we decided to explore the photosensitized oxygenation of