Zerwes, Ludger:
Untersuchungen zur Stereoselektion in einer Photo-Diels-Alder-Cycloaddition
Duisburg, 2005
2005book
ChemistryFaculty of Chemistry
Title:
Untersuchungen zur Stereoselektion in einer Photo-Diels-Alder-Cycloaddition
Author:
Zerwes, LudgerUDE
LSF ID
469
Other
connected with university
Place of publication:
Duisburg
Year of publication:
2005
Extent:
99 S.
DuEPublico 1 ID
Library shelfmark:
Note:
Duisburg, Essen, Univ., Diss., 2005

Abstract:

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.