- Transannular Hydride Shift versus Cyclocondensation in 5-(2-Biphenylyl)-10,11-dihydro-5H-dibenzocyclohepten-5-ol Derivatives
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The title compounds 1a-c, stable under thermal and basis conditions, undergo a solvent-assisted concerted hydride shift/deprotonation reaction to 5-(2-biphenylyl)-5H-dibenzocycloheptene (4) in weak acids such as acetic acid, acetic anhydride, phenol, and nitromethane.In strong acids like formic acid or trifluoroacetic acid cyclization to 10,11-dihydrospirocycloheptene-5,9'-fluorene> (3) occurs via the carbenium ion intermediate 5. - Key Words: Elimination/ Hydride shift/ Spirocyclization
- Hellwinkel, Dieter,Becker, Thomas
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p. 1595 - 1598
(2007/10/02)
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