| Abstract
| - A variety of diversely substituted 2-aroylaryl radicals,generated by photoinduced homolysis of 2-bromoarylketones,is shown to undergo Pschorr cyclization to yield fluorenonesin moderate to excellent yields. The photochemical resultsillustrate that the substituents in the two phenyl rings of the2-bromobenzophenone skeleton exert a dramatic influenceon the reactivity of the derived 2-aroylaryl radicals. Thedisubstitution by methoxy groups in the radical ring rendersthe aryl σ-radical highly electrophilic and unreactive forhydrogen abstraction and cyclization. On the other hand, thesubstituents in the non-radical ring that strongly stabilize thehydrofluorenyl π-radical, formed subsequent to the attackof the 2-aroylaryl radical on the non-radical ring, promotecyclization to furnish fluorenones in excellent isolated yields.
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