The photochemistry of some n-acylphthalimides
McSweeney, Nigel (1990) The photochemistry of some n-acylphthalimides. PhD thesis, Dublin City University.
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The photochemistry of N- alkylphthalimides has been
extensively studied while to date no work has been
published on N-acylphthtalimidea. We were interested in
the photochemical reactions of a range of
N-acylphthalimides with toluene and cyclohexene.
N-flcetylphthalimide. N-acetyl-3,4.5.6-tetrachlorophthalimide and N-benzoyl-3,4,5.6-tetrachlorophthalimide were found to behave photochemically like the carbonyl group of simple ketone systems by undergoing what appeared to be hydrogen abstraction at the "in-ring" carbonyl group of the excited phthalimide and recombination with the resultant benzyl radical to yeild the respective carbinols as the major products. N-Benzoylphthalimide when irradiated in toluene produced a novel spirolactone as the major product. We proposed the mechanism for its formation as involving a pinacol intermediate. The spirolactone formation may involve electron transfer from toluene to the excited N-J?enzoy lphthal imide whereas hydrogen abstraction may be the primary photoprocess on irradiation of the other studied N-acylphthalimides.
Irradiation of N-benzoylphthalimide, N-acetylphthalimide
and N-acety1-3,4,5,6-tetrachlorophthalimide ln the presence
of cyclohexene resulted in 1,4-cycloaddition of the
cyclohexene to the aromatic ring of the phthalimide as the
major photoprocess. X-Ray crystallography showed the
1.4-cycloadduct from the irradiation of
N-benzoylphthalimide in the presence of cyclohexene as the
exo, trans 1,4-cycloadduct. The exo. trans
1.4-cycloadducts were also the major products on
irradiation of N—acetylphthalimide and N-acety1-3,4,5. 6-
tetrachlorophthalimide in the presence of cyclohexene.
Minor products obtained on irradiation of
N-acylphthalimides in the presence of cyclohexene included
a carbinol by photoaddition of cyclohexene to the "in ring"
carbonyl group of N-acety1phthalimide and a novel
photoproducts which can formally be seen as insertion of
cyclohexene between the two "in ring" carbonyl groups of
N-acetyl-3.4,5.6-tetrachlorophthalimide with elimination of
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