Zur Photoreaktion 4-halogenierter 1-Acylnaphthaline mit alpha-Cyanenaminen - Photoreaction of 4-halogenated 1-Acylnaphthalenes with alpha-Cyanenamines

by Schmidt, Monika

Abstract (Summary)
During the electronic excitation of 4-halo-1-acylnaphthalenes in the presence of a-cyanoenamines one could not only observe the typical cycloaddition, but also substitution of the halogen through C-3 of the cyanoenamine in a high degree. The photoreaction of halogenated 1-acetonaphthones as well as 1-methyl naphthoates with a-cyanoenamines resulted as a rule in two substitution products and regioselective in two "head/tail" 1,2-cycloadducts. One exception is 4-chloro-methyl-1-naphthoate with an additional "head/head"-adduct. The main product in all explored reactions is the E-substitutionproduct. The halogen substituent has an influences on the reaction pathway; 4-bromoacylnaphthalenes show much higher yields of substitutionproduct, which is due to the lower dissociation energy of the C-Br bond. As expected the halogenated methylketones show higher reactivity than the methyl ester. The methylketones prefer 1,2-Cycloadducts with donor-anti and the esters with donor-syn orientation. There is every reason to be ieve that the reaction mechanism for the formation of the substitution products is based on an electron transfer from the olefin to the triplet excited aromatic compound.
Bibliographical Information:

Advisor:Prof. Dr. phil. Dietrich Döpp; Prof. Dr. rer. nat. Michael Tausch

School:Universität Duisburg-Essen, Standort Essen

School Location:Germany

Source Type:Master's Thesis

Keywords:chemie gerhard mercator universitaet


Date of Publication:12/11/2002

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