Untersuchungen zur Stereoselektion in einer Photo-Diels-Alder-Cycloaddition - Investigations on Stereoselectivity in a Photo-Diels-Alder-Cycloaddition

by Zerwes, Ludger

Abstract (Summary)
The photocycloadditions of 2-(dialkylamino)propenenitriles to 1-acetylnaphthalene in d6 benzene as solvent proceed with high directional selectivity by fast and photoreversible formation of [2+2]-cycloadducts (tetrahydrocyclobuta[a]naphthalenes) followed by a slower and photoirreversible formation of [4+2]-cycloadducts (1,4-dihydro-1,4-ethanonaphthalenes). With increasing duration of irradiation the product pattern is shifted towards a mixture of diastereomeric [4+2]-adducts in which the isomer with endo-orientation of the dialkylamino group in the ethano bridge is predominating. The endo-[4+2]-adduct of 2-(dipropylamino)-propenenitrile to 1-acetylnaphthalene was isolated in pure form, and its configuration was unambiguously corroborated by a single crystal X-ray structure analysis. Upon thermal activation it is converted in a small fraction via an intermediate biradical to the thermodyna-mically more stable exo-epimer before it is decomposed to the educts. Methyl 1-naphthoate reacts in the same way as 1-acetylnaphthalene but less efficiently.
Bibliographical Information:

Advisor:Prof. Dr. D. Döpp; Prof. Dr. W. Gärtner

School:Universität Duisburg-Essen, Standort Essen

School Location:Germany

Source Type:Master's Thesis

Keywords:chemie universitaet duisburg essen


Date of Publication:02/16/2005

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